34 posts • joined Thursday 27th December 2007 11:15 GMT
James Hansen Actually Said...
Arnold Lieberman wrote:
<blockquote>"He also bemoaned the “natural skepticism and debates embedded in the scientific process”"
I trust this quote is the beginning of his letter of resignation from The Enlightenment and rational thought in general. He certainly has put himself up with Mad Bob Mugabe in league of open minded thinkers...</blockquote>
Jim Hansen stated:
<blockquote>My testimony two decades ago was greeted with skepticism. But while skepticism is the lifeblood of science, it can confuse the public. As scientists examine a topic from all perspectives, it may appear that nothing is known with confidence. But from such broad open-minded study of all data, valid conclusions can be drawn.
My conclusions in 1988 were built on a wide range of inputs from basic physics, planetary studies, observations of ongoing changes, and climate models. The evidence was strong enough that I could say it was time to "stop waffling." I was sure that time would bring the scientific community to a similar consensus, as it has.
Guest Opinion: Global Warming Twenty Years Later
by James Hansen on June 23, 2008
Tipping Points Near
He was not bemoaning the natural skepticism inherent in the scientific process. He considers it critical to that process. However, such scientific skepticism should not be confused with Cartesian doubt -- as the climate "skeptics" would seem to have it.
Re: Science vs spin
Anonymous Coward wrote, "Science cannot predict because it can never be sure that all the factors have been accounted for or that new factors will not come to influence the situation. Science recognises that the past is no guide to the future and that the repetition of pairs of similar events in the same sequence does not entail any causal connection."
Sounds like philosophy 101. Hume, perhaps -- Reader's Digest version. Doubt it would go over all that well with engineers, electricians, or probably even the guys that make computer chips. In fact, I doubt it would be all that popular with the fellows who make nuclear bombs.
The people who build things, or in other cases blow things up. They want to know how things are going to behave - before they put them together. For that you need predictions. Not certainty, but a great deal of confidence. High probability. Close to 1 even. Or at the very least -- reliability. Especially with things that have a lot of pieces. Like that computer I presume you were sitting in front of when you typed on those keys.
Science is fallibilistic. It makes mistakes. But it is also self-correcting. And a conclusion justified by multiple, independent lines of investigation is often justified to a far greater degree than it would be by any one line regarded in isolation.
Science makes predictions based upon the best available evidence. When those predictions turn out to be wrong -- that's when scientists generally get excited -- because it means that there is something new to discover. Like a kid with a new toy.
But for your predictions to fail you have to be making them in the first place. Then when a prediction in fact fails you modify your theory or come up with an entirely new one, but preferably it should explain everything the earlier one did, making all the predictions that turned out to be right -- and succeed where the old theory failed.
Meditating on Water Vapour
This is in response to Alan Wilkinson's "Einstein had it right!" posted 6th January 2008 04:24 GMT regarding water vapour...
Alan Wilkinson wrote, "Likewise you have not given any reasonable answer to my original question as to how the natural runaway water vapour feedback loop is controlled. The only 'answer' you gave is a short residence time for water vapour - which is a classic 'begging the question' response, since what causes and controls the short residence time is of course the point at issue."
Alan, I explained that if one were to inject a parcel of water into the atmosphere, this would increase the rate of precipitation and decrease the rate of evaporation -- both due to the increased water vapour content of the air. Both an increase in the rate of precipitation (due to higher relative humidity and and greater frequency of saturation and therefore condensation) and a decrease in the rate of evaporation (due to the higher atmospheric water vapour pressure relative to the water vapour pressure of bodies of water) will tend to decrease the amount of water vapour in the air. And the greater the size of the parcel of water one injects into the atmosphere, the greater these two negative feedbacks.
I also explained that it takes a long time for the imbalance between incoming thermal radiation and outgoing thermal radiation to become balanced. A large part of this has to do with the thermal inertia of the ocean. It has a great deal of mass which takes alot of energy to heat up just a tenth of a degree, and the ocean has to heat up before it is able emit sufficient radiation (in accordance with the Planck-Boltzmann law, where radiation is proportional to the fourth power of the temperature) to balance the increased opacity of the atmosphere to thermal radiation.
However, if given a net reduction in evaporation and net increase in precipitation, the additional water vapor remains in the atmosphere for only a little more than a couple of weeks, the increased opacity of the atmosphere is an issue for only that long. And as such, in the case of an injection of water vapour into the atmosphere, the negative feedbacks increased precipitation and decreased evaporation are far more fast-acting than any positive feedback due to increased backradiation as the result of increased water vapour. And this is why water vapour is a feedback, not a forcing.
The physics behind this is fairly well understood. For example, the water vapour capacity of air is governed by the Clausius-Clapeyron relation:
... which also governs the partial pressure of water vapour at the phase boundary between the liquid phase (e.g., lakes and seas) and the gaseous phase (the water vapour in the atmosphere). From the Clausius-Clapeyron relation (along with the constants specific to water), one finds that saturation vapour pressure of water rises as an exponential function of temperature, doubling with roughly every additional 10 C. And like the Planck-Boltzmann law, this relationship is built into every climate model.
Now you can imagine an idealised world in which the atmosphere is kept the same uniform temperature and pressure throughout, perhaps looking at it in terms of a single column of water with a single column of air with a source of light shining down from above. In such an idealised world, it would be possible to calculate the trajectory of that world that would result from a pulse of water vapour in terms of a single differential equation.
However, our world is a little more messy than that, round world, days and nights, the seasons, continents and all. For example, air pressure falls roughly as an exponential function of altitude, being one-tenth of what it is at the surface 16 km up. As a result we have to use finite difference mathematics. But the principles remain the same. For example, we have the lapse rate of roughly 5 C per km in the Earth's troposphere -- where a constant lapse rate falls right out of the models. Likewise, in our world, relative humidity in the troposphere remains roughly constant with altitude, both as predicted by the models and as observed in reality.
Alan Wilkinson wrote, "So since we evidently don't understand this most fundamental point I can't see how we can have any faith in the accuracy of the models produced to date or of the consequences being predicted for increasing CO2 levels."
Alan, even if we didn't have the foggiest about how water vapour worked, there would still be the paleoclimate evidence and the evidence from the past century. But obviously we know a great deal more than nothing about water vapour. In fact we knew well enough that Hansen was able to project the trend in the average global temperature back in 1988 for the next twenty years -- and computers have sped up by over a factor of over a thousand since then. The calculations which we are doing nowadays take a great deal more into account.
We have a great deal of evidence that the Earth is warming -- and that it is warming at an unprecedented rate. We can see it in the landbased temperature record, the trend in tropospheric temperatures as measured by satellites, the sea surface temperatures, and the borehole temperatures. We can see it in the melting of the Arctic Sea ice and the glaciers. (That, incidentally is another one of those principles of physics: heat melts ice.) We can see it in the rise of sea level as warming ocean water expands, in the migration of species, and in the strengthening of storms, and we can see it in the spread of drought.
The evidence cries out for an explanation - and neither solar variability nor cosmic rays can do it since they have been essentially flat since 1952. We know what the radiative properties of greenhouse gases are -- we can measure them in labs and in the atmosphere. We know that their levels (mostly methane and carbon dioxide) have increased enough to significantly impact the radiation balance of the earth. And it would seem that we have a pretty good idea of how water vapour works, too.
"ABSTRACT: Climate models predict that the concentration of water vapor in the upper troposphere could double by the end of the century as a result of increases in greenhouse gases. Such moistening plays a key role in amplifying the rate at which the climate warms in response to anthropogenic activities, but has been difficult to detect because of deficiencies in conventional observing systems. We use satellite measurements to highlight a distinct radiative signature of upper tropospheric moistening over the period 1982 to 2004. The observed moistening is accurately captured by climate model simulations and lends further credence to model projections of future global warming."
Soden et al, The Radiative Signature of Upper Tropospheric Moistening, Science 4 November 2005: Vol. 310. no. 5749, pp. 841 - 844, DOI: 10.1126/science.1115602
Believe it or not, the alternative that faces humanity in science is not one between omniscience or blind faith. Just because we do not know everything does not mean that we know nothing. Science isn't a Cartesian game of doubt in which you accept only that which can be proven with absolute deductive certainty. Science is fallibilistic - it makes mistakes - but it is also self-correcting. It risks being wrong, but it goes with all the evidence which is available and gives us our best estimate of what to expect.
And going with all the evidence means taking into account all of the evidence we have available - since the justification for a conclusion supported by multiple lines of investigation is often far greater than the justification the conclusion would receive from any one line of investigation considered in isolation. You seem to be looking for a single reason to throw up your hands and say, "We can't understand it all and therefore we understand nothing." But science doesn't work that way.
This is in response to Alan Wilkinson 6th January 2008 04:24 GMT entitled "Einstein had it right!" regarding convection vs. radiation balance and trends in temperature
Alan Wilkinson wrote, "Living on a subtropical coast it is blindingly obvious to the most unscientific of us that surface and sea temperatures are largely controlled and affected by huge air and water convection systems, rather than local radiation balances. I am sure that the models contain some kinds of proxies for these systems, but whether they are adequate seems very doubtful."
It isn't a case of either/or.
Over the shortrun, "huge air and water convection systems" matter a great deal more than radiation balance -- particularly when you are living close to the ocean. I am thinking especially of the El Nino/Southern Oscillation, the North Atlantic Oscillation, the Pacific Decadal Oscillation and the Indian Diapole. These are what climatologists will often refer to collectively as "internal variability" or as climate modes. But they are oscillations. They don't result in long-term trends. They result in noise which makes it more difficult in the shortrun to identify trends in global temperature.
However, as I have pointed out, DePre Sys is beginning to take them into account by taking into account the distribution of heat content in the oceans -- something we weren't able to do in the past because we lacked the data. But technology has improved. And as a consequence, it appears that we are now able to make more accurate near-term climate projections -- over the decadal scale at least.
In an earlier post, I gave a paper showing how water vapour is behaving as predicted. Here is another - a formal detection and attribution analysis. Open access.
Santer et al, 2007: Identification of Human-Induced Changes in Atmospheric Moisture Content. PNAS, September 25, 2007.
Spencer, Exxon, etc
This is in response to Alan Wilkinson 6th January 2008 04:24 GMT entitled "Einstein had it right!" -- but specifically on the subjects of Spencer, Exxon funding, and the separation of science and religion. More than enough for one post.
Alan Wilkinson wrote, "Spencer refuted the false accusations you repeated about his funding in one of the links I gave."
Feel free to look up his refutation. But this is your assignment, not mine. However, as far as I can see, what I have given are simply well-established facts.
I stated, "Looking him up, I find that he is a member of four contrarian organisations, three of which are well-funded by Exxon to the tune of $1,601,500 since 1998 (contributing writer - Heartland Institute - $791,500, author - George C. Marshall Institute - $715,000, science roundtable member - Tech Central - $95,000)."
I gave the roles that he plays in those organisations and the funding they receive from Exxon, and I provided a link:
If you left-click on the icons representing Spencer and the individual organisations themselves you can get more details, if you wish. For example, they list the funding for each year and how it was obtained. Picking one at random, for the Heartland Institute for the year 2000, you have $115,000 ExxonMobil Foundation, Climate Change, Source: ExxonMobil Foundation 2000 IRS 990.
If you follow the link given there, it will bring you to a PDF of the IRS 990-PF -- which lists "charitable contributions" to a variety of organisations, including the Heartland Institute in the amounts of $15,000, $25,000 and $75,000 for that year. Similarly, sources are given for the roles that he plays in those organisations.
Alan Wilkinson wrote, "Spencer refuted the false accusations you repeated about his funding in one of the links I gave. He has religious beliefs that I don't share. So did my PhD supervising Professor. That didn't affect his science or our relationship at all."
Alan, I often have a great deal of respect for an individual's religious beliefs, and I even believe that an individual's religious beliefs can help make them a better scientist -- if they know how to distinguish between the two. But it would seem that Spencer has difficulty distinguishing between science and religion -- he supported intelligent design, for example, which seeks to mix the two, and which in my view would be destructive of both.
Furthermore, he belongs to the Interfaith Stewardship Alliance which apparently views the Bible (as it chooses to interpret the Bible) as some sort of authority in the realm of science, staking out the position that global warming in the twentieth century was "mostly natural" when mainstream science has concluded otherwise. He was one of the coauthors of their statement.
At the same time, I must admit that I do not know what the exact relationship between the funding, Spencer's religious beliefs and contrarianism are.
But the funding is part of a pattern -- where ExxonMobil is trying to distort the conclusions of science just as the tobacco industries tried to in the past -- through well-funded contrarian organisations which attempt to create the appearance of scientific disagreement where no actual scientific disagreement exists.
"ExxonMobil has manufactured uncertainty about the human causes of global warming just as tobacco companies denied their product caused lung cancer," said Alden Meyer, the Union of Concerned Scientists' Director of Strategy & Policy. "A modest but effective investment has allowed the oil giant to fuel doubt about global warming to delay government action just as Big Tobacco did for over 40 years."
January 3, 2007, Scientists' Report Documents ExxonMobil’s Tobacco-like Disinformation Campaign on Global Warming Science
Oil Company Spent Nearly $16 Million to Fund Skeptic Groups, Create Confusion
There is a link to the lengthy report by the Union of Concerned Scientists at that webpage above.
Likewise, through the American Enterprise Institute (an advocacy organisation they have been funding which has taken up tobacco industry causes in the past) they have been offering "honoraria" of $10,000 and other incentives to scientists would be willing to write articles criticising the IPCC's most recent report.
Here is a quote from an article on the program:
"Scientists and economists have been offered $10,000 each by a lobby group funded by one of the world's largest oil companies to undermine a major climate change report due to be published today.
"Letters sent by the American Enterprise Institute (AEI), an ExxonMobil-funded thinktank with close links to the Bush administration, offered the payments for articles that emphasise the shortcomings of a report from the UN's Intergovernmental Panel on Climate Change (IPCC)."
Scientists offered cash to dispute climate study
Ian Sample, science correspondent The Guardian, Friday February 2 2007
Here is a factsheet on the American Enterprise Institute:
SourceWatch: American Enterprise Institute
And as for the letters offering such inducements...
From one letter - the first paragraph:
"The American Enterprise Institute is launching a major project to produce a review and policy critique of the forthcoming Fourth Assessment Report (FAR) of the Intergovernmental Panel on Climate Change (IPCC), due for release in the spring of 2007. We are looking to commission a series of review essays from a broad panel of experts to be published with the release of the FAR, and we wat to invite you to be one of the authors."
... and the last paragraph:
"If you and Prof. XXX are agreeable to being authors, AEI will offer an honoraria of $10,000. The essay should be in the range of 7,500 to 10,000 words, though it can be longer. The deadline for a complete draft will be December 15, 2007. We intend to hold a series of small conferences and seminars in Washington and elsewhere to coincide with the release of both the FAR and our assessment in the spring or summer of 2007, for which we can provide travel expenses and additional honoraria if you are able to participate."
A copy of one of the letters is available here:
Bush allies offer scientists $10,000 to attack UN climate report
Friday, 2 February 2007
Alan Wilkinson wrote, "His comment about the self-correcting nature of our weather was plainly a speculation but surely a reasonable one, ..."
I have already pointed out that the sort of mechanism which Spencer vaguely alludes to would be just as effective against warming due to increased solar insulation as it would be to increased longwave backradiation. You have put forward a vague ad hoc hypothesis that sunspots or cosmic rays might be involved which would some how save his ad hoc hypothesis. I have pointed out that you cannot explain late twentieth century warming by reference to solar variability or cosmic rays because the trends with respect to both have been essentially flat.
Alan Wilkinson wrote, "... given that our climate has supported life for so long. It is hard to argue that that could have resulted had not negative controlling feedback systems predominated over positive runaway ones."
We aren't talking about runaway feedbacks, not something which would result in our planet becoming like Venus. The feedback is limited. Best estimates, a doubling of CO2 with all the feedbacks (negative and positive) leads to an increase in the global average temperature of 3 C -- based upon current and paleoclimate evidence.
However, while our planet has supported life for a very long time, there have been many major extinction events in the history of our planet, and four out of the five greatest extinctions appear to have been driven by the release of carbon dioxide in large quantities into the atmosphere by flood-basalt supervolcanoes.
And as I have pointed out, the greatest of these, the Permian/Triassic Extinction occured 251 million years ago, wiping out 90 percent of all marine-based species and 70 percent of all land-based species. Fortunately we don't look like we are headed for anything quite like that -- but given our current trajectory, what we are headed towards looks like it will be quite devastating.
Given the Permian/Triassic Extinction and other such events in the Earth's history, how can you claim that the negative feedbacks predominate over the positive feedbacks? That feedback from the hydrological cycle isn't primarily positive? How can he?
The speculation which you speak of and find "reasonable" flies in the face of the paleoclimate record. And the evidence that we have seen in the twentieth century is for a climate sensitivity which is nearly the same as it has been for the past 460,000 years. Roughly 3 C -- although we can't really rule out significantly higher climate sensitivities.
However, at some point, depending upon how far this goes, the positive feedback that we are currently seeing from the weakening major carbon sinks could very well turn into net emissions. At that point climate change will begin to take on a life of its own, independently of us.
This is in response to Alan Wilkinson's "Einstein had it right!" posted 6th January 2008 04:24 GMT regarding Artic warming.
Alan Wilkinson wrote, "In the last few days there has been publicity about studies showing that much of the recent Arctic warming has been due to natural climate cycles rather than AGW."
I presume you are speaking of the news stories going off of a throwaway statement in the following paper:
Rune G. Graversen, Thorsten Mauritsen, Michael Tjernström, Erland Källén & Gunilla Svensson, Vertical structure of recent Arctic warming, Nature 451, 53-56 (3 January 2008)
At the end of the article, they make the comment,
"Our results do not imply that studies based on models forced by anticipated future CO2 levels are misleading when they point to the importance of the snow and ice feedbacks. …. Much of the present warming, however, appears to be linked to other processes, such as atmospheric energy transports."
As such they are criticising the models as claiming that the feedback responsible for polar amplification is due to the albedo effect. However, they do not actually examine the models in the paper. Hence my calling it a throwaway statement, particularly since it has very little to do with the subject of the study. And as a matter of fact, the models show a number of feedbacks as being responsible for polar amplification. The feedback due to the albedo effect is simply one of the easiest to explain to a lay audience.
For example, In the abstract for the following paper, a variety of elements thought to play a role in polar amplification as analyzed by climate modeling are mentioned — and the albedo effect is nowhere to be found:
"The Arctic is among the regions where climate is changing most rapidly today. Climate change is amplified by a variety of positive feedbacks, many of which are linked with changes in water vapor, cloud cover, and other cloud properties. We use a global climate model to examine several of these feedbacks, with a particular emphasis on determining whether there are significant temporal changes in these feedbacks that would make them stronger or weaker during the 21st century. The model results indicate that one of the significant positive feedbacks on Arctic surface air temperature in winter weakens substantially toward the end of the 21st century. The feedback loop begins with a temperature increase that produces increases in water vapor, cloud cover, and cloud optical depth which increase the downward longwave flux by 30 Wm^-2 by 2060 which then increases the surface air temperature."
Miller et al, Future regime shift in feedbacks during Arctic winter
Geophysical Research Letters, Vol. 34 doi:10.1029/2007GL031826, 2007
Shortly afterwards, they state:
"The amplification of high-latitude climate change results from complex positive feedbacks involving exchanges of energy and water mass between the ocean, sea ice, and atmosphere. The positive feedback related to changes in sea-ice albedo is one of the most frequently mentioned, however there are other positive feedbacks that are also important. Among these are feedbacks related to water vapor and clouds. Chen et al. [2003, 2006] demonstrated the importance of correctly representing in climate models the relationships among Arctic cloud and radiative properties. The present paper examines how some of these relationships and feedbacks may change in simulations of future climate."
Afterwards they go on to cite some of the very same elements Graversen et al is concerned with — within the contexts of climate models. As with earlier studies, Miller et al argues that downward longwave flux plays an important role, one it gives centerstage, which is involved in a variety of positive feedback loops — which vary in strength and relative importance according to time and place (e.g., water vapor vs. cloud optical depth).
Finally, Miller et al state that their results are consistent with a polar amplification being driven by an increased water vapor, leading to a polar amplification which is strongest during the winter due to increases in open water and latent heat flux — as modeled:
"Although this paper has not specifically examined the part of the feedback loop that produces the increase in atmospheric water vapor, this increase is consistent with modeled winter increases in open water and latent heat flux in the study region."
As I have said, I believe the albedo effect is most often mentioned as a cause of polar amplification because it is the easiest to understand. But judging from Miller et al (2007) at least and what it states with regard to literature, I find it difficult to believe that someone familiar with the literature would be unaware of other mechanisms being in play in model polar amplification.
In any case, they weren't claiming that the warming is simply part of a natural cycle, but that it isn't well-modeled by current models -- without examining the models themselves. And their statement was made out of ignorance of what processes the models actually show to be important.
This is in response to Alan Wilkinson's "Einstein had it right!" posted 6th January 2008 04:24 GMT
Alan Wilkinson wrote, "You claimed my post contained obvious mistakes. Please list them, because I see no justification for that statement in your posts - rather a desperate resort to "consensus" claims, ad hominem attacks and a diversion back to the original article as apparently an easier target."
Alan, your entire post consisted of the following:
1. "The last word ought to be the scientific uncertainty of the predictions - in accordance with Timothy's comment that science is always a work in progress."
2. "The ten year forecast for global temperatures (2004-2014) provided by the improved model (DePreSys) referenced by Timothy is for a warming of 0.1 - 0.5 degrees C (95% confidence level). This is apparently a revision downwards from previous models."
3. "This only marginally excludes the null hypothesis and the error in this estimate cannot include unknown model deficiencies and physical phenomena."
4. "I think anyone who claims the science is settled doesn't understand the issues."
As such you didn't leave me much to refute.
However, your central error is in treating the decade prediction by DePre Sys in isolation as if it is the only evidence for anthropogenic warming.
We have the warming trend for the entire twentieth century. We have the physics which explains that trend. We have the mechanism, an enhanced greenhouse effect due to higher levels of carbon dioxide resulting in more backradiation -- based upon well-understood radiation transfer theory with well-measured spectra, in the labs, at the surface and by satellite. We have paleoclimate evidence which shows this mechanism in action at various points in the earth's history. And we have a large number of phenomena which models have correctly predicted -- that I have previously listed on numerous occasions, the cooling of the stratosphere, stronger warming trend at night and in the wintertime, the polar amplification, the expansion of the Hadley cells, etc..
I went into all that and more.
With respect to your claim #4, you provide only your assertion. And as I have shown just recently, there is a long list of large scientific bodies which seem to believe otherwise. Somehow I think they are more credible.
Finally, as for the "diversion" back to the original article, I would think that that was getting us back on track -- since that was the basis for this thread. But in any case, that provided me with a lead-in to deal with the issues in the post that followed. (Originally it was all the same post as I was responding to both your posts at the same time -- but this was too large to post as a single post.)
House of Lords Select Committee (was GW Models)
On 5th January 2008 23:29 GMT David Robinson wrote, "In U.K. last year a House of Lords Select Committee (they don't come higher than that here) investigated the claim that a large majority of leading scientists backed the gloal warming claim. It found that a "healthy majority" in fact did not believe in the claim. It also found that many leading scientists were very angry by being claimed to be in favour by the IPCC against their wishes. The committee also found that GW claims were illfounded."
Dave, you heard wrong regarding the House of Lords Select Committee. The following is from the report issued by that committee:
"13. The Committee heard from several scientific witnesses on the theory. No one disputes the fact of temperature rise in the last 100 years or so. No one disputes that carbon dioxide is a greenhouse gas and few dispute that it has an enhanced "greenhouse effect". What is disputed, albeit by a minority of scientists, is the scale of this effect. In the view of Professor Richard Lindzen of MIT, current climate models would have predicted a substantially greater increase in the past temperature than has been observed in the past 150 years, perhaps +3oC compared to the +0.6oC we have witnessed. In his view, this suggests that the models are biased upwards and that, while warming will occur, it is the lower end of the IPCC spectrum that is relevant, not the upper limits, which he regarded as "alarmist". Our understanding of the scientific response to this apparent anomaly is that (a) cooling effects, including those from sulphates, have masked the expected rise in warming, and (b) only climate models that combine natural variability and anthropogenic forcings "fit" the past data, as outlined in paragraph 15.
"14. We recognise that there is a strong majority view on climate change. Majorities do not necessarily embody the truth, but we note that major associations of scientists have adopted similar positions. The IPCC tends to be the focus of the majority view which has been confirmed by the Royal Society, and by the US National Academy of Sciences, the American Meteorological Society, the American Geophysical Union and the American Association for the Advancement of Science. Despite this, it is a concern that the IPCC has not always sought to ensure that dissenting voices are given a full hearing. We document these concerns later in the Report."
Select Committee on Economic Affairs Second Report
CHAPTER 2: The Uncertain Science of Climate change
The greenhouse effect
I would like to make four points regarding the text I have quoted:
1. The fact that that temperature has risen over the past century is undisputed: "No one disputes the fact of temperature rise in the last 100 years or so."
2. The fact that CO2 has a greenhouse effect is not disputed: "No one disputes that carbon dioxide is a greenhouse gas and few dispute that it has an enhanced 'greenhouse effect'."
3. There is a strong majority view: "We recognise that there is a strong majority view on climate change."
4. The IPCC represents that view: "The IPCC tends to be the focus of the majority view which has been confirmed by the Royal Society, and by the US National Academy of Sciences, the American Meteorological Society, the American Geophysical Union and the American Association for the Advancement of Science."
Furthermore, I would like to point out that as the result of their investigation, the committee established the Stern Review:
Stern Review on the economics of climate change
... which concludes:
"Climate change is a serious and urgent issue… There is now an overwhelming body of scientific evidence that human activity is increasing the concentrations of greenhouse gases in the atmosphere, and causing warming."
Re: GW Models
Dave Robinson wrote, "Timothy makes the usual AMG claims about the scientific support for people causing global warming. I would point out that, at an IPPC conference for leading world's scientists 3 or 4 years ago, after 5 days of talks given the conference was asked to vote on the motion that 'mankind is affecting the the climate'. The vote was 13% for and 87% against. When giving a resume to the press the IPPC reversed the vote, saying to the press that 87% voted for and only 13% against. Needless to say what got published. Would you trust an organisation that lied like that?"
What are we talking about -- a conspiracy, Dave? And all the scientists chose to keep quiet? Were their families threatened? Do you have any references, either with regard to this claim or that about the select committee?
It's not just the IPCC, Dave.
You have two joint statements by the National Academy of Sciences, one for eleven countries, one for sixteen countries....
National Academy of Sciences, joint statement by:
Academia Brasileira de Ciéncias (Brazil),Académie des Sciences (France), Accademia Nazionale dei Lincei (Italy), Russian Academy of Sciences (Russia), National Academy of Sciences (United States of America), Royal Society of Canada (Canada), Deutsche Akademie der Naturforscher Leopoldina (Germany), Science Council of Japan (Japan), Academy of Science of South Africa (South Africa), Chinese Academy of Sciences (China), Indian National Science Academy (India), Academia Mexicana de Ciencias (Mexico), Royal Society (UK)
National Academy of Sciences, joint statement by:
Australian Academy of Sciences, Royal Flemish Academy of Belgium for Sciences and the Arts, Brazilian Academy of Sciences, Royal Society of Canada, Caribbean Academy of Sciences, Chinese Academy of Sciences, French Academy of Sciences, German Academy of Natural Scientists Leopoldina, Indian National Science Academy, Indonesian Academy of Sciences, Royal Irish Academy, Accademia Nazionale dei Lincei (Italy), Academy of Sciences Malaysia, Academy Council of the Royal Society of New Zealand, Royal Swedish Academy of Sciences, Royal Society (UK)
There have also been separate statements issued by the following organisations:
Union of Concerned Scientists, Woods Hole Research Center, Intergovernmental Panel on Climate Change, United Nations Framework Convention on Climate Change, American Association for the Advancement of Science, American Meteorological Society, National Research Council, Canadian Meteorological and Oceanographic Society (CMOS), Federal Climate Change Science Program, National Oceanic and Atmospheric Administration (NOAA), UN Project on Climate Variability and Predictability, American Geophysical Union, Geological Society of America, American Chemical Society - (world's largest scientific organization with over 155,000 members), Federal Climate Change Science Program, 2006 - commissioned by the Bush administration in 2002, Stratigraphy Commission - Geological Society of London - The world's oldest and the United Kingdom's largest geoscience organization, Engineers Australia (The Institution of Engineers Australia), American Association of State Climatologists, US Geological Survey (USGS), National Center for Atmospheric Research (NCAR), NASA's Goddard Institute of Space Studies (GISS), Woods Hole Oceanographic Institute – Ocean and Climate Change Institute, World Meteorological Organization, United Nations Environment Program, Canadian Foundation for Climate and Atmospherice Sciences, International Council on Science, State of the Canadian Cryosphere (SOCC), Environmental Protection Agency (EPA), American Astronomical Society, The Australian Meteorological And Oceanographic Society, American Institute of Physics, Pew Center on Climate Change, World Wildlife Fund
There are also petitions signed by individual scientists, including one that has been signed by over 12,000.
To see the statements, please visit:
It has links to the documents themselves.
A Matter of Justification: back to the article
Alan Wilkinson wrote, "The last word ought to be the scientific uncertainty of the predictions - in accordance with Timothy's comment that science is always a work in progress."(Predictive Uncertainties - 3rd January 2008 08:21 GMT)
I didn't respond to this comment earlier as you clearly wanted the last word -- and I thought that the mistakes you were maken were obvious enough that others would see them without my having to point them out. But as you followed up with another more rhetorical comment I will respond to both.
I stated that science is always a work in progress, but it does progress.
There is a great deal which the models are getting right. The cooling of the stratosphere, polar amplification, nights warminging more raidly than days and winters more rapidly than summers. These are all effects that are predicted specifically as the result of an enhanced greenhouse effect. And they also predicted a super greenhouse effect in the tropics -- which has been observed.
Likewise, they predicted the expansion of the Hadley cells which govern the extent of the tropics, changes in ocean circulation resulting from land warming more rapidly than ocean, the expansion of the range of cyclones, and they get tested using paleoclimate records and hindcasting. Furthermore, Jim Hansen's Scenario B, the product of a single run using a model was primitive by today's standards, that was presented to US Congress back in 1988 has been nearly deadon for its forcast of temperature rise for the past 20 years.
But then there are also areas where the models would seem to need more work. Models had been predicting that summer Arctic sea-ice would last for several decades -- and now its looking like it will be gone within a decade. But by increasing the resolution of the models, one team was able to capture the processes that would seem to be leading to its early demise (particularly oceanic advection) and estimate that it may be gone as early as 2013. And this is independent of the evidence from the meltback of 2005 and 2007.
We do not know everything, but the fact that we do not know everything does not imply that we know nothing.
"The ten year forecast for global temperatures (2004-2014) provided by the improved model (DePreSys) referenced by Timothy is for a warming of 0.1 - 0.5 degrees C (95% confidence level). This is apparently a revision downwards from previous models.
"This only marginally excludes the null hypothesis and the error in this estimate cannot include unknown model deficiencies and physical phenomena." (Predictive Uncertainties - 3rd January 2008 08:21 GMT)
If the hypothetical evidence from the ten year forecast for the current decade were all that we were basing our claim that the world is currently warming due to the effects of greenhouse gases, then the case for anthropogenic global warming would be very weak indeed. For one thing, much of that decade has yet to be seen. However, as I have pointed out above, there is a great deal of evidence for such warming and for the dominant mechanism behind that warming.
But simply in terms of warming trends, it would be a mistake to take the decade from 2004-2013 in isolation -- as much of the twentieth century shows much of the same trend. The evidence is cummulative -- and much of the case is built upon solid physics -- well established scientific principles in radiation transfer theory, thermodynamics, fluid dynamics and chemistry. Although the exact numbers differ from competing climate model to climate model, all climate models indicate that the primary cause of 20th century warming is our carbon dioxide emissions. And they provide us with strong justification to conclude that despite the variability due to climate modes (e.g., the El Nino/Southern Oscillation, North Atlantic Oscillation, Pacific Decadal Oscillation and Indian Ocean Diapole) which may obscure trends on decadal scales (so much that climatologists generally do not consider trends in global temperature significant unless they are at least fifteen or twenty years in length), this warming trend will continue for some time even if we were to halt our emissions today.
Alan Wilkinson writes, "I think anyone who claims the science is settled doesn't understand the issues," and then later states, "We understand the science of static systems but applying it to such mobile and interacting complex multi-state systems is a whole different ballgame." (Predictive Uncertainties - 3rd January 2008 08:21 GMT, Greenhouse - 3rd January 2008 20:52 GMT)
The vast majority of those in mainstream science would appear to disagree.
The case for anthropogenic global warming is so strong yet result in so much popular press controversy that a great many major scientific organisations have found it necessary to issue statements, and every major scientific organisation which has issued a statement has come down squarely on the side on anthropogenic global warming.
There is an extensive list of links to the statements by these scientific organisations may be found here:
Evidently they do not consider "mobility," interaction, the presence of multiple states or complexity to represent fundamental limits upon what science may reasonably conclude given the evidence which we have to date. There are areas of considerable uncertainty and genuine scientific controversy, but not with respect to the basics of anthropogenic global warming.
Alan Wilkinson writes, "It certainly doesn't help to overstate certainty on either side of the possible debate, and it is very unhelpful to demonize or belittle participants in a kind of religious warfare." (Greenhouse - 3rd January 2008 20:52 GMT)
Mainstream climatologists and other scientists generally acknowledge where uncertainties exist and the areas in which there still exists room for considerable progress.
But for a moment, let's focus specifically on the paper that was the basis for the article for this thread.
First, they pick an out of date dataset with which to judge models, a dataset which is known to contain problems specifically in the area which they are comparing to model results and use it to judge the performance of the models without any acknowledgement of the uncertainties in that data product. Second, due to errors in their statistical math, they greatly underestimate the ensemble model uncertainty. Third, they claim the inconsistency between the invalid dataset and the climate models demonstrate that an enhanced greenhouse effect cannot be the cause of current global warming as because the dataset shows a lack of sufficient tropical troposphere amplification -- when this isn't specific to an enhanced greenhouse effect, but given current models would result from generally any cause of warming.
They state, "We have tested the proposition that greenhouse model simulations and trend observations can be reconciled. Our conclusion is that the present evidence, with the application of a robust statistical test, supports rejection of this proposition. (The use of tropical tropospheric temperature trends as a metric for this test is important, as this region represents the CEL and provides a clear signature of the trajectory of the climate system under enhanced greenhouse forcing.)"
Where is their uncertainty?
Tropospheric amplification is not a "signature effect" of an enhanced greenhouse effect. This signature effect would be the predicted result of our models just as much from increased increased solar insulation as from an enhanced greenhouse effect. For something comparable which is a "signature effect" of an enhanced greenhouse effect, I would suggest the cooling of the stratosphere -- which we have seen a great deal of over the past decades.
A number of these authors have made similarly unqualified and outlandish statements in the past which have proven just as unsupportable in the past. It is typical of what is found in contrarian literature.
But why is this?
Reasons to Believe
Permit me to quote a passage from a Newsweek article in order cast some light on why the positions of mainstream climatology are under attack today:
"'Warming of the climate system is unequivocal,' concluded a report by 600 scientists from governments, academia, green groups and businesses in 40 countries. Worse, there was now at least a 90 percent likelihood that the release of greenhouse gases from the burning of fossil fuels is causing longer droughts, more flood-causing downpours and worse heat waves, way up from earlier studies. Those who doubt the reality of human-caused climate change have spent decades disputing that. But Boxer figured that with 'the overwhelming science out there, the deniers' days were numbered.' As she left a meeting with the head of the international climate panel, however, a staffer had some news for her. A conservative think tank long funded by ExxonMobil, she told Boxer, had offered scientists $10,000 to write articles undercutting the new report and the computer-based climate models it is based on. 'I realized,' says Boxer, 'there was a movement behind this that just wasn't giving up.'"
-The Truth About Denial, Sharon Begley, Aug 13, 2007, Newsweek
ExxonMobil has offered scientists a $10,000 reward for articles that purport to undercut the IPCC WG1 AR4 (2007) report detailing the evidence for anthropogenic global warming.
Likewise, I have pointed out that they provide a great deal of funding for contrarian organisations arguing against anthropogenic global warming.
I gave the following link earlier detailing which organisations the authors of the current study are associated with and what documented funding those organisations have received from Exxon since 1998:
Fred Singer alone is associated with 13 such organisations which have received $3,911,200 since 1998 -- with over $3,000,000 in funding since 1998 having gone to ten Exxon-funded organisations which he is still participating in.
Was the financing of preordained conclusions and nonexistent uncertainty in contrarian literature by the Tobacco industry consistent with the nature of the scientific enterprise in past decades? Singer was one of the authors of such pro-Tobacco literature. Is such financing by the fossil fuel industry consistent with it today?
Alan Wilkinson writes, "It certainly doesn't help to overstate certainty on either side of the possible debate, and it is very unhelpful to demonize or belittle participants in a kind of religious warfare." (Greenhouse - 3rd January 2008 20:52 GMT)
Granted, but who is expressing unfounded certainty?
Earlier you stated, "Finally, this is a good, readable summary that appeals to me in logic and tone..." (Clouds: Chicken vs Egg - 1st January 2008 02:31 GMT) then quoted a passage from an article by Spencer where he states,
"The most important example of this lack of understanding is, in my view, how precipitation systems control the Earth's natural greenhouse effect, over 90% of which is due to water vapor and clouds. The Earth's total greenhouse effect is not some passive quantity that can be easily modified by mankind adding a little carbon dioxide -- it is instead constantly being limited by precipitation systems, which remove water vapor and adjust cloud amounts to keep the total greenhouse effect consistent with the amount of available sunlight. Our understanding of this limiting process is still immature, and therefore not contained in the models."
Spencer's statement has more than a hint of teleology in it, the view that nature is goal-directed in such a way that "precipitation systems control the Earth's natural greenhouse effect," that this effect cannot "be easily modified by mankind adding a little carbon dioxide."
He is quite skeptical of the mainstream science for which there is a great deal of evidence, stating "our understanding of this limiting process is still immature, and therefore not contained in the models," but he has unshakeable confidence (one might even say "faith") that such a limiting process exists "... which remove water vapor and adjust cloud amounts to keep the total greenhouse effect consistent with the amount of available sunlight." In fact, "faith" would seem to be the appropriate term since we have a great deal of paleoclimate evidence and evidence from the past century which demonstrate quite the opposite.
Looking him up, I find that he is a member of four contrarian organisations, three of which are well-funded by Exxon to the tune of $1,601,500 since 1998 (contributing writer - Heartland Institute - $791,500, author - George C. Marshall Institute - $715,000, science roundtable member - Tech Central - $95,000).
Now let's consider the fourth organisation to which Spencer belongs. It is called the Interfaith Stewardship Alliance.
Their homepage states,
"The Interfaith Stewardship Alliance (ISA) is a coalition of religious leaders, clergy, theologians, scientists, academics, and other policy experts committed to bringing a proper and balanced Biblical view of stewardship to the critical issues of environment and development. The ISA fully supports the principles espoused in the Cornwall Declaration on Environmental Stewardship, and is seeking to promote those principles in the discussion of various public policy issues including population and poverty, food, energy, water, endangered species, habitat, and other related topics."
Is the Interfaith Stewardship Alliance's view consistent with the scientific enterprise? It would seem that they are concerned that the conclusions of mainstream science may not be consistent with the Bible as they choose to interpret it, or so it would seem when you read the actual text of the Declaration that they endorse:
"At the same time, however, certain misconceptions about nature and science, coupled with erroneous theological and anthropological positions, impede the advancement of a sound environmental ethic."
Interfaith Stewardship Alliance -- Cornwall Declaration
In fact, the Interfaith Stewardship Alliance has staked out a position contrary to that of mainstream science.
GLOBAL WARMING MAINLY NATURAL and Not Catastrophic,
Says New Study from Interfaith Stewardship Alliance
Spencer is listed as one of the coauthors of the statement by the Interfaith Stewardship Alliance.
Is Spencer's attitude consistent with the scientific enterprise?
Considering how you found the passage of his you quoted (and that I showed just above expresses an unshaking faith in a teleology which limits or prevents anthropogenic global warming) appealing in tone and logic, is yours?
Re: Water Vapour Sensitivity
Alright, I'll bite....
This is in response to Alan Wilkinsons's post of 3rd January 2008 04:05 GMT...
Alan Wilkinson wrote, "Your point about the questionability of CO2 impact being suppressed when solar impacts are not (did you mean Christy - I thought that was Spencer) could be answerable if cloud formation (eg seeding) is affected directly by sunspot or cosmic radiation or by particulate matter, but not by 'greenhouse' gases. At the moment that is just speculation though."
Looking back, Spencer.
With regard to your solution, you are multiplying hypothetical mechanisms.
First, the hypothetical mechanism where increased longwave radiation is responsible for reducing cloud cover in just such a way that the longwave radiation will open a window for itself through the clouds to let out the excess longwave radiation. And yes, we are seeing a reduction in cloud cover in the tropics, but whatever longwave radiation is escaping is almost exactly equal to the increase in shortwave radiation. As such it isn't counterbalancing any greenhouse effect -- or the increase in longwave radiation that results from increased temperatures.
Second, the hypothetical mechanism pertaining to sunspots/cosmic rays. And the problem with this is that, other than the periodic behavior of solar cycles, solar activity has been roughly flat since roughly 1950, and yet the rate of temperature rise has increased -- considerably since about 1979. And cosmic rays have been essentially flat for the same period of time -- except without the benefit of any quasi-cyclic/chaotic behavior.
And look: you were counting on the tropical clouds opening up as a means of explaining why things are getting warmer, and are at this point seeking to use them as a means of explaining why things won't heat up.
And then there are aerosols. Now of course I wouldn't argue that aerosols do not have an effect. They do, direct and indirect albedo effects. However, both of these effects are measurable at the surface in terms of global dimming. Of course, what we had been experiencing for a bit prior to the turn of the century is global brightening -- a reversal of the trend of global dimming, presumably.
So how does this fit in?
Given the fact that land temperatures increased by nearly one degree Celsius (0.8 C CRU) from 1960 to 2000, for solar brightening to be responsible for the rise in temperature after the "flat period" from 1952 to 1975 during which aerosols were a major factor, it would have to be greater than the solar dimming within the same 1960-2000 period. However, solar dimming outweighed solar brightening over this period.
"Recent solar brightening cannot supersede the greenhouse effect as main cause of global warming, since land temperatures increased by 0.8 C from 1960 to 2000, even though solar brightening did not fully outweigh solar dimming within this period."
Impact of global dimming and brightening on global warming
Martin Wild, Atsumu Ohmura, and Knut Makowski
Geophysical Research Letters, Vol. 34, L04702, doi:10.1029/2006GL028031, 2007
Now I noticed you put quote marks around the term "greenhouse" in the phrase "greenhouse gases"...
1. We can measure the infrared properties of greenhouse gases in laboratories, measuring their absorption lines in painstaking detail, with over a million absorption lines being part of a database which began as a military project.
2. We can measure the backradiation at various points in the spectra from greenhouse gases, effectively fingerprinting them by means of this.
3. We can measure their concentrations at different altitudes by means of their emissions from satellites.
4. We can measure altitude by means of the opacity of the atmosphere to their lines of absorption.
5. We cannot explain the temperature of the Earth, Venus or Mars without reference to their effects.
6. Given the column distribution and spectra of greenhouse gases , we can calculate the strength of their greenhouse effect and compare it with what we get from satellite measurements. The spectra are known quite accurately, column distribution, fairly accurately. Things match.
7. One can virtually derive the absorption spectra of greenhouse gases from quantum mechanics.
8. We have four out five of the major extinctions tied to flood-basalt supervolcanoes. Carbon dioxide suddenly skyrocketed, it did so roughly at the time of the eruptions, and temperature went up at the same time. Would you suggest that sunspots or cosmic rays are causing supervolcanoes?
9. We can explain the timing of the glacials/interglacials in terms of the periodic cycles in the earth's orbit -- which are predictable by means of Newton.
10. We cannot explain the amplitude of the glacials/interglacials without reference to both ice sheets and amplification by means of the carbon cycle. Are the solar cycles or cosmic rays going to be that sensitive to the position of the earth? To its tilt?
11. With a solar effect you are still going to need to explain why warming takes place in the troposphere but cooling takes place in the stratosphere. Greenhouse gases can do that with increased opacity to thermal radiation -- by the fact that they trap thermal radiation between the troposphere and the surface. Going off of solar irradiance at least, you would expect either both to warm or cool.
12. You are still going to have to explain why the winters warm more quickly than the summers, and the nights more quickly than the days. We have those nailed in terms of greenhouse gases as well. But going off of solar irradiance at least would tend to give you the opposite effect.
Now I am not saying that it is logically impossible for some other explanation of the current warming trend to exist -- or even that it is logically impossible for some other explanation to be right. But science does quite well by stearing clear of Descartes and hewing to its fallibilistic, self-correcting methodology -- in which it goes where the evidence leads and does not multiply explanatory principles beyond necessity.
Anyway, if we continue with the discussion, it will have to be a little slower -- I have things I need to attend to, and I need to get on a regular sleep schedule. Also, I am not sure how long The Register will be that interested in continuing with it.
However, if you would prefer, we could exchange emails if this is something which you would genuinely like to explore together. Still, it would have to be slower.
Here is my address:
tim o thy chase -at- gmail -dot- com (minus the spaces)...
... but I may not always be prompt as I tend to get wrapped up in projects. (I know, I know -- hard to believe.)
My Last (was Imbalance)
Alan Wilkinson wrote, "So although I've posted a few interesting links I don't claim to know the literature at all and am interested in what Timothy has to say since he does seem to be active in the field. I'm not trying to debunk climate change or global warming. I'm just trying to understand the issues and put the most challenging questions I see."
I'm not active in the field. Just a former philosophy major (focused on the theory of knowledge and philosophy of science) turned computer programmer who got interested in evolutionary biology for a few years then climatology about nine months ago. I tend to get obsessed with understanding things -- and get involved in long discussions at times. The discussions help me think, learn from others, clarify my own understanding -- and perhaps give me a chance to illuminate a little.
To give you an example from a while back, over at real climate, we went into the greenhouse effect in a fair amount of depth, even getting into non-local thermodynamic equilibria between radiation and matter, differences between spontaneous emission (what the greenhouse effect works off of) and stimulated emission (as with lasers), the fact that non-greenhouse gases can absorb and emit thermal radiation as well due to collisions temporarily changing their shape, the fact that neither prototypical line radiation (which is discrete - how the radiation emitted by gases is first thought of) nor prototypical blackbody radiation (which is continuous - how the radiation emitted by liquids and solids is first thought of) actually exist in the real world, as the lines have widths, and liquids and solids simply have a great many more, broader lines due to the closer interaction) and its all thermal radiation, etc..
But even after having gone through all of this, I had come to the position that the atmosphere was heated first by moist air convection after reradiating the energy back to the surface. Somehow it had escaped me that when the thermal radiation is absorbed by the atmosphere and the energy exchanged by molecular collision prior to being reemitted, that implied that the thermal radiation had warmed to atmosphere. I didn't figure that part out until several weeks later when someone else brought it up in a discussion -- who incidentally was rather dubious about the greenhouse effect, if I remember correctly.
Anyway, you had mentioned viewing things as pulses vs viewing them as feedback circuits. Its a difference of perspective -- what aspect of the climate system you wish to focus on at the time. A pulse helps simply in terms of viewing what happens when we put so much gigatons of carbon dioxide into the air, but if you want to see how the climate system is a shifting, self-maintaining system, obviously you would want to be looking primarily at the network level of feedback circuits.
But in this discussion, we have been looking at this largely in terms of just water vapour. Thats one network. However this isn't the most essential network for climatology. It is principally concerned with the energetics of the system. Energy entering the top of the atmosphere, being absorbed at the surface, by the land and oceans, the thermal radiation which gets emitted and then absorbed by the atmosphere and clouds.
And yes, the moist air convection as water evaporates at the surface, the latent heat which gets released with the condensation into clouds, with some of it being radiated towards space or back towards the ground. Then obviously there is the carbon cycle, which at a rather basic level is analysed the same way as the energy and water. A network with pulses, cycles, residence times for a given molecule in a pool (e.g., atmosphere, land-based life, soil, ocean, geologic) and residence times for a pulse, where some of the pools exchange carbon more easily than others.
I will make one quick point about John Christy though: from what I can see, his hypothetical cloud mechanism for insuring that the climate system doesn't respond to forcing by carbon dioxide (i.e., the increased radiation received at the surface by thermal emissions from increased levels of carbon dioxide in the atmosphere) would seem to be equally good at insuring that the climate system doesn't respond to increased sunlight. In which case the the warm spells after ice ages become a mystery.
But then again, if the climate system doesn't respond to increased levels of carbon dioxide, the cycles between the glacials and interglacials are quite mysterious as well, since according to the calculations, orbital variations aren't enough to explain those cycles without some amplification from both the carbon cycle and ice sheets. And then there are the major extinctions which we believe are tied to higher levels of carbon dioxide due to supervolcanoes. And what's been happening to the glaciers, the West Antarctic Peninsula and Arctic Sea Ice.
However, there is evidence that at least in terms of the parameterizations of moist air convection, we do not entirely understand what is going on in the tropics. This is what one of the links you sent in was about -- decreased tropical cloud cover. Likewise, we had underestimated the rate of ice loss in the Arctic Sea. Much of this would seem to be the result our grid being too course to capture the advection -- flow of warm water from the lower latitudes. And for a while the polar vortex was a problem until they started using shorted increments of time. We don't have everything figured out, and science will always be a work in progress. But it does progress.
In any case, my sleep schedule has been a mess, and with the beginning of the new year I need to get started on a few things. But thank you for the discussion, particularly Alan. It has been more along the lines of a dialogue than a debate, and I believe they can generally be a great deal more rewarding for everyone involved. I guess there will always be a few loose threads unfortunately, but they can serve to act as starting points for future discussions amongst us or others we meet.
Re: Clouds: Chicken vs Egg (Hatzianastassiou)
A note for the readers: This is in response to Alan Wilkinsin's comment of 1st January 2008 02:31 GMT. Alan has brought up several papers which bring us into what may be an odd territory for some. As I have pointed out earlier, clouds have both an albedo effect which cools and a greenhouse effect which warms. The albedo effect is what people normally associate with clouds.
Thus it might seem that by reducing the level of clouds you will warm the surface. However, there is a fellow by the name of Lindzen who some time ago proposed the "iris effect" where a reduction in clouds might lead to cooling because the reduction in clouds would let the thermal radiation out rather than trapping it. This is largely what the links in "Clouds: Chicken vs Egg" deal with. Largely. But in any case, it will help to know that OSR stands for outgoing (reflected) shortwave radiation -- or sunlight whereas OLR stands for outgoing longwave radiation, and TOA standards for top of atmosphere.
Currently I will be focusing on just one author: Hatzianastassiou.
Alan pointed us to the following paper:
Clouds and aerosols have impacts on global temperature at least comparable to greenhouse gases: http://www.atmos-chem-phys.net/7/2585/2007/acp-7-2585-2007.pdf
Honestly, that looks interesting. I particularly like the fact that they are using a finer resolution on their spectra.
However, the first thing that I would note is that they are speaking of the Direct Radiative Effect of dusts and aerosols. This is not the same thing as a forcing -- although it is expressed in the same units. When forcings are calculated, they are calculated relative to quasi-equilibrium conditions, or alternatively, relative to a given base year. For example, in some of the calculations referenced in the IPCC WG1 AR4, you will see references to a base year of 1750. Alternatively, NASA GISS will tend to use 1880. But as such, when the authors compare the effects of dusts/aerosols to greenhouse gases, they are actually comparing apples to oranges.
Now this might not be as great a problem as it first seems if the dusts/aerosols which they were considering were strictly anthropogenic in nature -- such that we could trace them back to the effects of industrialisation, such that we might think their effects to be relatively small in comparison to the present day value. However, as they are mixing both natural and anthropogenic dusts/aerosols (including sea spray, apparently), they provide us with no means of knowing to what extent their direct radiative effect is simply part of the natural background of the climate system, something which, although changing from season to season, has remained unchanged for centuries or even millenia.
At no point do they perform any sort of trend analysis, but only averages for different seasons from a period of ten years, demonstrating seasonal change providing no evidence of any significant decadal trend. To the extent that it has remained unchanged, it would provide no basis for an explanation of climate change. However, simply going off the paper itself, I would conclude that this was not their intent.
Rather, I would conclude that they seek to emphasise the role of dusts/aerosols as a causal factor in determining the radiation balance and consequent temperature of the climate. This would be a significant development in climatology if it lead to an improvement in the models. However, if this was in fact the intent of the paper I would have to question why they chose to compare apples and oranges in the first place.
Now Alan has also directed us to what appears to be an abstract of some sort:
0.0.1 A Global Cloud Cover Climatology from 17-year ISCCP-D2 Data
Oddly enough by the same author as before. It is interestingly worded and contains interesting patterns of words. I will skip to the end where the author no doubt thinks it is most interesting:
"Our analysis has shown that the decrease in cloudiness has taken place mainlyin the tropical areas between 20°S and 20°N, while it has occurred during the period from the early 1990s to the year 2000. Such changes in cloud cover are consistent with observed and computed trends in shortwave and longwave radiative fluxes both at the top of atmosphere and at the Earth’s surface, and they are very important for the atmospheric dynamics and circulation, and the climate of the Earth-atmosphere system, whereas they can counteract or exceed changes induced by other climatic change agents."
However, it does not contain the name of any journal or publication date.
So I decided to look for other studies by Hatzianastassiou on cloud coverage in the tropics...
Here is a passage from one of them:
"A significant decreasing trend in OSR anomalies, starting mainly from the late 1980s, was found in tropical and subtropical regions (30° S-30° N), indicating a decadal increase in solar planetary heating equal to 1.9±0.3Wm-2/decade, reproducing well the features recorded by satellite observations, in contrast to climate model results. This increase in solar planetary heating, however, is accompanied by a similar increase in planetary cooling, due to increased outgoing longwave radiation, so that there is no change in net radiation. The model computed OSR trend is in good agreement with the corresponding linear decadal decrease of 2.5±0.4Wm-2/decade in tropical mean OSR anomalies derived from ERBE S-10N non-scanner data (edition 2). An attempt was made to identify the physical processes responsible for the decreasing trend in tropical mean OSR."
Analysis of the decrease in the tropical mean outgoing shortwave radiation at the top of atmosphere for the period 1984-2000, A. Fotiadi, et al, Atmos. Chem. Phys., 5, 1721-1730, 2005
(Hatzianastassiou is the second author listed.)
The authors attribute the reduction in outgoing (reflected) shortwave radiation to a reduction in clouds. This is something which at least some models had difficulty replicating. However, since the reduction in outgoing (reflected) shortwave radiation is matched by an increase in the outgoing longwave radiation, the net effect is neither to cool nor warm the tropics.
Important to understanding the climate system? Perhaps. But is not a mechanism for explaining rising temperatures, nor is it an instance of the so-called iris-effect where the clouds open up to let out thermal radiation which would otherwise result in a warming trend when there are increasing levels of greenhouse gases. A rising surface temperature implies increased longwave radiation being emitted from the surface. But this would be something on top of the increase in outgoing longwave that balances the reduction in outgoing (reflected) shortwave.
Additionally, we have known since 1997 that under clear skies in the tropics at temperatures of 27 C or above, downwelling longwave radiation can increase more rapidly than upwelling longwave radiation as a function of sea surface temperature. It called the super greenhouse effect.
F.P.J. Valero, et al., Direct radiometric observations of the water vapor greenhouse effect over the equatorial Pacific Ocean, Science, 274(5307), 1773-1776, 21 March 1997
Getting rid of the clouds won't get rid of the greenhouse effect if higher temperatures result in higher absolute humidity, increasing the strength of the greenhouse effect under clear skies.
PS Re: Another question - clouds
Regarding my comment posted Monday 31st December 2007 20:51 GMT
The second sentence should have read, "The individual runs are calculating all the relevant physical variables for a three-dimensional grid, and these aren't average values but individual values."
Other typos, but I will let them go. Alan -- I am enjoying the discussion, and I will be posting a little later.
Re: Water vapour sensitivity
Alan Wilkinson wrote, "A small increase in water vapour will generate a small increase in temperature thus supporting a further small increase in water vapour ...."
What you seem to be thinking of is roughly speaking a geometric sum with an infinite number of terms -- and although you may not intend this, to some it may seem that you are suggesting that since it has an infinite number of terms, the geometric sum will increase without limit. However, infinite geometric sums often have finite limits. For example, (1/2)+(1/4)+(1/8)+.... = 1 where each term is half that of the term before it. In the limit.
Alan Wilkinson wrote, "There must be other factors controlling this process. Residence time is not one of them."
If you are speaking of a climate model, insofar as every element interacts with a large of other elements which taken as a whole constitute a single climate system, then yes, of course there will be other factors, but residence time will be one of them.
The fact that a given pulse of increased atmospheric water vapour will rapidly decay long before it has the chance to raise temperature due to its increased greenhouse effect is of central importance in this context. The rapid decay is largely due to the imbalance between increased precipitation and reduced evaporation given the increased albedo of clouds while the system is near the initial temperature, where both the higher precipitation and lower evaporation will have the effect of on the net removing water vapour from the atmosphere. The gradualness of the process through which the climate system reachieves the balance between incoming and outgoing radiation and the rapidity with which water vapour on the net is removed from the atmosphere implies that water vapour should be treated as a feedback, not as a forcing.
In contrast, depending upon the initial perturbution from equilibrium, carbon dioxide may play either the role of a feedback or a forcing.
With the glacial cycles it is playing the part of a feedback.
Periodic changes in the earth's orbit due to the presence of Jupiter and Saturn affect the amount of sunlight the earth receives and where the sunlight falls. A small rise in the average temperature of the earth over a long enough period of time reduces the extent of the glaciers and the capacity of the oceans to absorb carbon dioxide and to hold on to the carbon dioxide which they already have.
Reducing glaciers increases the absorption of solar energy, and increased levels of carbon dioxide reduces the rate at which the climate system is able to radiate thermal energy to space. Both processes amplify the initial effect of increased incoming solar radiation. At this point carbon dioxide is acting as a feedback.
But with four out of five of the major extinction events (as well as other events in the earth's history), carbon dioxide plays the part of a forcing.
251 million years ago, the Permian-Triassic extinction began with a pyroclastic flood-basalt supervolcano erupting in Siberia. The eruption itself lasted roughly a million years. It sent large quantities of carbon dioxide into the atmosphere. Pyroclastic events sent dust and sulfates into the atmosphere, resulting in some temporary reduction in the amount of sunlight reaching the surface for years.
Lava flow burned large forests, but judging from the chemical evidence, some of the lava which reached the ocean caused large quantities of methane to be released from their icy hydrate prisons in the shallows along the edges of the continental plates. The initial rise in levels of carbon dioxide and methane are not a response of the climate system, but are part of how the climate system is initially disturbed, in this case by a geologic event.
At this point temperature follows carbon dioxide, and in this case, to some extent methane.
Then of course there will be the slow feedbacks -- where carbon dioxide plays the role of a forcing in the initial pulse but the role of feedback in the climate system response.
After the eruption in Siberia 251 million years ago, there were changes in icesheets which lagged well behind changes in temperature, and likewise feedbacks from the carbon cycle itself. The rise in temperature reduced the rate at which the ocean absorbed carbon dioxide and increased the rate at which it released carbon dioxide until the increased level of carbon dioxide in the atmosphere and reduced level of carbon dioxide in the ocean brought these two rates back into balance at quasi-equilibrium.
The increased levels of carbon dioxide in the atmosphere due to higher temperatures is feedback -- as would be methane produced by swamps or the more general rise in temperature of the oceans. But it is the pulse of carbon dioxide from the eruption and the methane which is released from the methane hydrates by lava flow which are treated in the calculations as initial inputs rather than as calculated quantities, and therefore which are regarded as forcings.
Of course, the same thing at least in principle might be done with water vapour at some point. For example, if one found that the amount of water vapour being released into the atmosphere by industry was having a significant enough effect upon the climate system, there it would be treated as a forcing -- since it wouldn't be treated as a calculated result of the climate system reacts to a disturbance, but would be treated as an input in the calculations.
However, the atmospheric water vapour resulting from increased evaporation from the oceans would still be a feedback. But water vapour from industry won't build up to levels that are significant enough to affect the climate system in that way so as to be generally included in the calculations as a forcing.
Re: Another question - clouds
This is in response to the comment posted Monday 31st December 2007 03:22 GMT
Alan Wilkinson wrote, "But average temperatures are inadequate for a model that depends on radiative transmissions proportional to the fourth power of temperature. You must know the distribution of temperature extremes to use a model like that. If they change, so will the radiation balance."
Granted. The individual runs are calculating all the relevant physical variables for a three-dimensional grid, and these are average values but individual values. Then given slightly different initial conditions (typically in which one varies the heat content of a few cells in the ocean) and let the butterflies take it from there, one will arrive at different runs. Then with the ensemble of these runs, one can calculate average values for a given period of time, one can calculate the variation or spread, and one can compare various statistical measures of a large variety of physical variables (temperature at different altitudes, pressure, wind, soil moisture, humidity, downwelling infrared, cloud fraction, rainfall, etc.) at different levels (global, continental, latitudinal, seasonal, etc.) against what is actually observed.
And likewise, you could compare trends seen in a model's ensemble with trends seen in the world. For example, does a given model's ensemble reproduce the same linear trend towards increased rain during the winter that we see in England for the past forty years? Or better yet, does it underestimate or overestimate the slope, and if so, by how much?
Of course, what we are more focused on an present are usually at a higher level than trends in precipitation in England during the winter. Generally global trends, trends for a given continent, but also the behavior of the El Nino / Southern Oscillation (ENSO), Atlantic Oscillation, Indian Diapole, etc.. The latter is a large part of what is involved in Hadley's DePreSys, what is making it more accurate. That and the fact that as we take into account the global distribution of heat content in the upper layers of the ocean, we are able to initialise the models with the real world data.
Then instead of simply varying a little of the heat content in the oceans as we have done in the past, we are able to initialise individual runs with real world data, in this case from consecutive days, and rather than simply focus on the long-range forcasts we are able to do decadal forcasts. DePreSys consequently shows greatly improved hindcasts when compared with the same model where that model is not initialised with the real world data, particularly over the decadal range.
For more information on DePreSys, please see for example the article I refered to earlier:
Improved Surface Temperature Prediction for the Coming Decade from a Global Climate Model, Science, Aug 10, 2007, Doug M. Smith, et al
Re - falsification or testability of climate models
This is in response to Alan Wilkinson's post of 31st December 2007 07:05 GMT
I had written, "If by 'mathematical relationship model stage,' you mean that climate models are simply going off of correlations, I would of course have to disagree -- but I am not sure that this is what you mean."
Alan Wilkinson responded, "No, I didn't mean that. I understand the models are based on numerous physical theoretic mathematical relationships. In that sense they are like a composite of Newton's laws and many others. This weakens the testability of them rather seriously as they are effectively many hypotheses resulting in only a small number of testable predictions."
The physics and chemistry which the models are based on are already a well-supported part of the fabric of our scientific understanding of the world. They have been bought and paid for by the science done over the past several centuries. We are speaking of Newton's gravitational theory -- general relativity doesn't make that much of a difference under earth conditions. We are speaking of thermodynamics -- such as when we use the Clausius-Clapeyron relation to determine the partial pressure of carbon dioxide or water vapor coming off the ocean, and it dates back to 1834.
We have the spectra of greenhouse gases, bought and paid for by countless laboratory experiments, with data describing over a million lines of absorption and their strengths stored in the HiTran database. This detailed work began as part of a project by the military in the 1980s to study the transmission of infrared radiation through the earth's atmosphere -- for military purposes.
However, it is virtually derivable from the first principles of quantum mechanics as they apply to the vibrational, rotational and rovibrational states of molecules as electromagnetically-induced quantized states of excitation subject to exponential decay. Climatologists use Stefan-Boltzmann's law -- which you are of course familiar with -- that was discovered in 1879 and derived theoretically in 1884.
They make use of heat capacity at constant volume and pressure -- but these are well studied and well known. They make use of the equations governing compressibility and thermal expansion, such as when they calculate the predicted flow of glaciers or predict the thermal expansion of the earth's oceans - but deny them these well-known and well-supported principles and you lose your mechanical thermometers. And these too are ultimately derivable in terms of statistical quantum mechanics.
Do you have any idea how well-tested these principles are? In how many areas they are applied? How much evidence we have accumulated for them? How much modern technology relies upon their being right? And how exactly would you go about testing a climate model if you didn't have recourse to earlier scientific theories for which we have accumulated a wealth of evidence? Upon what principles would your instruments be based?
One way or another, you would have to assume such well-justified physical principles, in terms of the principles of optics, radiation transfer theory, thermodynamics, or fluid dynamics when using satellites, thermometers or other instruments to observe the weather or distribution of various atmospheric constituents or measure the concentrations of gases and dusts in the atmosphere and chemicals in the ocean. And if at some point they turn out to be mere approximations as in the case of Newton's gravitational theory, ask yourself whether using a more exact theory will make any difference in the predictions which follow.
In the case of Newton's gravitational theory, you are able to estimate its limits by recourse to general relativity. By reference to the latter more advanced theory, you are able to demonstrate that whatever predictions you might make under earth conditions by employing the former will be consistent with the theory that superseded it.
By making recourse to the science which is already known and well-supported, we are able to ask a great many questions that we would otherwise lack the language or even concepts to ask. By using the principles of such of such established science, we are able to make a far wider range of far more exacting predictions regarding the behavior of the biosphere, hydrosphere, atmosphere and electromagnetic spectra.
Without recourse to such well-established science, we would still be groping for the Ancient Greek elements of earth, water, air and fire. By bringing together such well-established principles, we are able to reduce the number and scope of additional assumptions which must be made in order to predict the behavior of the climate system as a whole.
At some level, all of empirical science and even human knowledge is an experiment of sorts. It is fallible. It is possible that by bringing together these principles and using them together and making predictions that we will discover some of their limitations. But if so, this will also afford us the opportunity to learn something more. Science is fallible, it makes mistakes, but it is also self-correcting. It is only by bringing together the elements of our scientific understanding that we achieve scientific progress and further the growth of science.
"And the testability is also limited by the large data uncertainties inherent in estimating the historic record which currently is the only data that gives a significant model test over substantial changes in environmental variables."
There are large uncertainties in many cases. However, one reduces many of these uncertainties by recourse to well-established scientific knowledge, using the physical principles describing radioactive decay, for example, to date various materials, or the principles chemistry to estimate the the temperatures that existed at various points in the earth's history by means of various chemical proxies.
By combining various lines of evidence, one narrows the uncertainties. And the justification a conclusion receives from multiple lines of investigation is often far greater than that which it would receive from any one line of investigation considered in isolation from the rest. This is the insight underlying our use of Bayesian logic -- although it goes far deeper and is far more basic.
Properly, science is a unity because the reality it studies is a unity. The true is the whole.
Infrared Imaging and Re: Popper vs Testability
I am going to respond shortly to you comment (much of which I agree with, incidentally), but first I would like to make available samples of the kind of information we are able to get via infrared imaging. I would like to combine things and make this my last post - unless someone (yourself included of course) wants to bring up some other issues.
The following images carbon dioxide rising up from industrialised centres at 8 km by means of its infrared emissions:
Products - AIRS Carbon Dioxide
NASA AIRS Mid-Tropospheric (8km) Carbon Dioxide
The following page has QuickTime movies showing the evolution over a two month period of total column ozone, carbon monoxide, water vapour concentration at half surface pressure, outgoing longwave radiation, cloud fraction, the three-dimensional structure of a storms water vapour with layers peeled away, atmospheric temperature at 500 mb, etc. all using infrared imaging based upon the absorption/emission spectra of various atmospheric constituents - and includes a movie explaining in detail how it is done:
The following will give you more information on what is being done elsewhere:
Visualization of the global distribution of greenhouse gases using satellite measurements, by Michael Buchwitz. The Encyclopedia of Earth. Posted July 31, 2007
... and of course there is more. Could provide some more links a little later if anyone is interested. But this is the some of the data that we are testing the new models against, obviously.
Now your post dealt actually with two issues - my short piece on Popper that I provided a link to and the scientific status of climate models, that is, how advanced they are. I will deal with them in that order, but keep the bit on Popper as short as I can since I doubt it will be of general interest.
The two central issues with regard to Popper's Principle of falsifiability is the question of whether advanced scientific theories are in fact falsifiable and whether or not they ever receive any justification such that they may properly be regarded as true. Contrasting his view with induction, he makes it clear that in his view, scientific theories may never be regarded as receiving justification. Instead, what distinguishes scientific theories from other forms of knowledge is the fact that they make predictions such that if those predictions turn out to be false, such theories may be regarded as falsified. Regarded in this way, they are capable of being demonstrated false, but never true.
However, with advanced scientific theories it is generally impossible to test them in a manner that is independent of other theories. For example, when one creates an instrument for measuring the angle of light which has presumably been bent by passing too close to the sun, or a theory of celestial motion, or even of human psychology -- to the extent that one finds it necessary to depend upon the accounts given by others. To test a given advanced theory, one must generally assume that the theories which are in the background (those being relied upon in order to test the advanced theory) are themselves true.
Now I go on to argue that justification exists in degrees, and as such, we tentatively regard theories which are successful as a form of knowledge (what is refered to as "corrigible knowledge"), but that they remain open to being tested in the future. But given the fact that they have been tested and have acquired a degree of justication which may be far greater than the theory which is in the foreground, they may be assumed which testing that theory - but in this case, a negative result cannot strictly be regarded as falsification (which would be categorical) but as disconfirmation (which is a matter of degree). However, falsifiability may still be regarded as an ideal which theorists and experimentalists should aim for even though in the strictest sense it is generally something that cannot be achieved.
Incidentally, I wouldn't begin to think that what I gave above constitutes a systematic philosophy of science, and as a matter of fact there is much in your post that I agree with. But this is my disagreement with a strict principle of falsifiability as layed out by Karl Popper. My position is actually fairly mainstream and traces its roots to Duhem's Thesis from 1892. (Popper has belonged more to the history of the philosophy of science than to the philosophy of science pretty much since the 1950s.)
Alan states, "As far as I can see as an ex-physical scientist layman, climate science is still back at the mathematical relationship model stage and suffers from insufficient testability in relation to the number of degrees of freedom inherent in the parameters of those models. I suspect this is the basis for much scientific scepticism of the AGW predictions."
Once again, I need to yin-yang this a bit.
If by "mathematical relationship model stage," you mean that climate models are simply going off of correlations, I would of course have to disagree -- but I am not sure that this is what you mean. But my point is simply that they are going off of the physics, whether it happens to be in terms of measurable spectral absorption, fluid dynamics, thermodynamics, or... Well, with the incorporation of the carbon cycle, for example, experiments will actually be done with an organic soup in sea water where they will subject it to turbulence to see how much carbon dioxide and methane are released.
But this will be according to a very specific recipe, including how the turbulence is generated such that the experiments being used to generate the formula are something which can be precisely duplicated. Likewise, with plants, algae and so on, they will incorporate a certain highly deliminated set of well studied, representative species where they know what the response of those species are to temperature, precipitation, soil moisture, water salinity and so on -- as the result of extensive experiments. The carbon cycle is at its early stages, and in some respects the biological world which they create seems quite artificial. But what is important to them is that it is precisely defined -- and can be methodically extended over time.
Now there are certainly approximations that are used. Formula which aren't exact, but which permit them to perform the calculations more quickly. No doubt this is a large part of the reason why different models will often give somewhat different results. That and the fact that different models will have different physics incorporated into them, some which may better simulate ocean or atmospheric chemistry, for example, or the physics of light.
But as near as I have been able to tell so far, the models are constructed entirely out of local laws, principally physics and chemistry, but now also "laws" which govern members various representative species of life. Not much room for tinkering or adjustable parameters.
However, one area where we know there is substantial disagreement between various models is with climate sensitivity. This is where you might get the impression that there are too many degrees of freedom. But climate sensitivity isn't something which gets plugged into the models -- it is something which falls out of them. They will run experiments with different levels of carbon dioxide, do an ensemble of runs to the new equilibrium, then calculate the climate sensitivity based upon the carbon dioxide and the final temperature.
What results in different models obtaining different results? The physics which gets incorporated into the models, the resolution with respect to various variables (time, space and spectra), species of aerosols, the time-saving approximations, and undoubtedly a fair number of butterflies.
But the fact is that we aren't entirely dependent upon the models for calculating climate sensitivity. There is the manner in which volcanoes disturb the climate system and it returns to equilbrium is another avenue, for example. But there is also the paleoclimate record - 460,000 years worth - which strongly suggests that it is 2.9 C per doubling or somewhat above. And additionally, we know that just as ensembles of runs give us a better indication of what behavior we should expect from the climate system, ensembles of models tend to do better at predicting the behavior of the climate system than models considered in isolation.
So consequently, it is possible to combine multiple lines of evidence by means of bayesian logic and arrive at a better estimate of what the climate sensitivity actually is - with a narrow range of uncertainty than what you would get from any one line of evidence considered in isolation. The result? About 2.8 C or somewhat above. Same result as what we get from the paleoclimate record for the past 460,000 years, more or less. About the same figure that was estimated back in the 1960s.
PS to Re: Water vapour sensitivity
Dupped different versions of the same paragraph. I don't know as if I have ever done that before, but I suppose it is a hazard of writing in Notepad, then pasting into the form. Got into the habit of doing things that way when I lost posts due to my browser crashing a while back.
Re: Another simple question
Alan writes, "Stand outside and feel the temperature. The differences on a cloudy day (cooling) and on a cloudy night (warming) are huge compared with clear skies. In comparison even the currently modelled impacts of vast CO2 increases are minor. Do we really understand cloud, convection and precipitation drivers well enough to have any confidence in these skeletal simplifications of our complex weather patterns?"
The effects of CO2 are slow but steady. There is a great deal of variation within winter or summer, but we know that on the average days in winter are so much colder than days in summer, and this is because of the amount of radiation the top of the atmosphere is receiving. Carbon dioxide acts pretty much the same way, affecting the average.
Climate models aren't trying to calculate the actual weather on a particular day twenty or forty years from now at a particular location. They are trying to calculate what the average weather and variation in that weather will be either for the globe or for a region will be at "around that time." In all honesty, though, I would be quite hesitant to trumpet much in the way of regional results as of yet.
However, as I have noted, they have done quite well at predicting the cooling of the stratosphere, polar amplification, nights warming more quickly than days and winters more quickly than summers, the expansion of the Hadley cells, a super greenhouse effect where backradiation rises more rapidly than thermal radiation from the surface as the water surface temperature rises above 30 C, that land warms more quickly than ocean, the expansion of the range of hurricanes and cyclones.
They are tested against paleoclimate records, volcanic eruptions which disturb the climate system for years, and by means of hindcasting. And moreover, Scenario B from 1988 was predicted to be a better match than A and c by Hansen before the US Congress in 1988 -- and it has been pretty much dead on for the past twenty years. And that was using just a single run for each scenario rather than ten or so runs to more fully probe the attractor -- using a model with a lower resolution and much less of the physics.
Incidentally, here is something Hadley just came out with a little earlier this year: DePreSys
Improved Surface Temperature Prediction for the Coming Decade from a Global Climate Model
Science, Aug 10, 2007, Doug M. Smith, et al
Hadley is also working on extensive, global realtime monitoring of pressure, temperature, etc.. But it is the distribution of the heat content in the ocean which matters most over the time frame of a decade. Probably longer. Oh, and you should see the information we are able to get from satellites. I will get a few links out tomorrow.
Re: Water vapour sensitivity
Alan wrote, "Your argument about precipitation doesn't seem to hold water. Whether the temperature rise is solely due to water vapour itself or to CO2 plus water vapour the effect is the same. Same temperature, same clouds, same precipitation, same cooling, same control. Residence time makes no difference. Same equilibrium between temperature, partial pressure of water vapour (= humidity) and precipitation."
Assuming you inject so water vapour into the atmosphere above the equilibrium level for a given a given temperature, the amount of water vapour in the atmosphere (or alternatively, absolute humidity) will return to its equilibrium level before the water vapour has the chance to significantly raise the temperature. Increased humidity means increased cloud formation and increased precipitation. The residence time of water vapour in the atmosphere is approximately ten days.
However, assuming a longer residence time for carbon dioxide, higher levels of carbon dioxide a greenhouse effect which raises the temperature, increasing the absolute humidity of the air (in a fashion that is roughly proportional to an exponential function of the temperature) where the increased water vapour will remain in the atmosphere due to the higher temperature and will also have its own greenhouse effect - resulting in some additional amplification.
Alan wrote, "Incidentally the half life of CO2 in atmosphere is relatively short - I understand about three years - not thousands. The argument that CO2 added incrementally will take so long to be removed given the size of the natural carbon cycle seems weak to me. But let's stay on the water vapour cycle first."
How do you explain the rising levels of carbon dioxide in the atmosphere since we began measurements in 1958?
Typically the figure given is a half-life of 300 years. However, according to the following paper, with anywhere between a 300 to 5000 GT release of carbon dioxide, while a "halflife" of 300 years is a fair approximation for much of the carbon dioxide, 25% of the carbon dioxide from such a release will "remain" in the atmosphere far longer with 6-7% remaining in the atmosphere even after 100,000 years.
Archer, David (2005), "Fate of fossil fuel CO2 in geologic time", Journal of Geophysical Research 110 (C9): C09S05.1-C09S05.6, doi:10.1029/2004JC002625, http://geosci.uchicago.edu/~archer/reprints/archer.2005.fate_co2.pdf
And here is another paper you might want to check:
Caldeira, Ken & Wickett, Michael E. (2005), "Ocean model predictions of chemistry changes from carbon dioxide emissions to the atmosphere and ocean", Journal of Geophysical Research 110 (C9): C09S04.1-C09S04.12, doi:10.1029/2004JC002671, http://www.ipsl.jussieu.fr/~jomce/acidification/paper/Caldeira_Wickett_2005_JGR.pdf
According to the following paper, with anywhere between a 300 to 5000 GT release of carbon dioxide, while a "half-life" of 300 years is a fair approximation for much of the carbon dioxide, 25% of the carbon dioxide from such a release will "remain" in the atmosphere far longer, with 6-7% remaining in the atmosphere even after 100,000 years. (Incidentally, 300 GT is roughly what we put into the atmosphere each year.) This also receives support from the paleoclimate record.
Typically the figure given is a half-life of 300 years. However, according to the following paper, with anywhere between a 300 to 5000 GT release of carbon dioxide, while a "halflife" of 300 years is a fair approximation for much of the carbon dioxide, 25% of the carbon dioxide from such a release will "remain" in the atmosphere far longer with 6-7% remaining in the atmosphere even after 100,000 years. The slowest process is that of remineralization.
Archer, David (2005), "Fate of fossil fuel CO2 in geologic time", Journal of Geophysical Research 110 (C9): C09S05.1-C09S05.6, doi:10.1029/2004JC002625, http://geosci.uchicago.edu/~archer/reprints/archer.2005.fate_co2.pdf
And here is another paper you might want to check:
Caldeira, Ken & Wickett, Michael E. (2005), "Ocean model predictions of chemistry changes from carbon dioxide emissions to the atmosphere and ocean", Journal of Geophysical Research 110 (C9): C09S04.1-C09S04.12, doi:10.1029/2004JC002671, http://www.ipsl.jussieu.fr/~jomce/acidification/paper/Caldeira_Wickett_2005_JGR.pdf
... and incidentally it appears that several natural carbon sinks becoming saturated somewhat ahead of schedule:
Southern Ocean saturated with carbon dioxide-study
17 May 2007 18:00:14 GMT
Rapid Decline of the CO2 Buffering Capacity in the North Sea and Implications for the North Atlantic Ocean, Thomas, H. et al., Global Biogeochemical Cycles, October 6, 2007 (Vol. 21, GB4001, doi: 10.1029/2006GB002825)
Knorr, W., N. Gobron, M. Scholze, T. Kaminski, R. Schnur, and B. Pinty (2007), Impact of terrestrial biosphere carbon exchanges on the anomalous CO2 increase in 2002–2003, Geophys. Res. Lett., 34, L09703, doi:10.1029/2006GL029019
Re: What if?
Jim Black wrote, "The reason(s) for the warming periods (and cooling periods) that have been documented seem to be missing from the discussion. Mr. Chase does comment that rising CO2 levels have previously resulted in warming although other sources have indicated that the rise in CO2 levels was in fact a lagging indicator, not a leading indicator."
I mentioned them. Degassing of the oceans due to increased solar insolation as the result of orbital cycles when temperature leads carbon dioxide, but apparently flood-basalt eruptions and methane hydrate releases in four out five of the major extinctions where carbon dioxide lead temperature.
Given a climate system which starts in equilibrium and then a disturbance which results in a rise or fall in either temperature or carbon dioxide, you will see a rise or fall in the other as the result of feedback.
Jim Black wrote, "The evidence tying mankinds activities to a causal factor in the warming is much more tenuous. The link reminds me of the old false saying that 'All cancer victims drink water, thus water causes cancer.'"
It sounds like you think scientists are saying "There is a correlation, therefore there is causation." This isn't the case since we know the physics.
By "mankind's activities," I presume you mean raising the level of carbon dioxide in the atmosphere. Quite measureable. The connection to warming? Infrared radiation gets absorbed in accordance with the spectral properties of carbon dioxide as measured in labs with measurements of spectral lines for carbon dioxide and other gases composing more than a million entries in the HiTran database, then reradiated isotropically, half towards space, half towards the ground, reducing the rate at which energy leaves the climate system.
The backradiation which gets absorbed by the surface warms it. Because the radiation gets absorbed and reradiated isotropically, we say that the atmosphere in more opaque to thermal radation. And things will have to continue to warm up until enough radiation is able to make it through the atmosphere to balance the thermal energy which is entering the system as the result of the absorption of sunlight. This follows from the principle conservation of energy.
And incidentally, are able to image the reemission of radiation from different greenhouse gases at different altitudes in the atmosphere (using satellites that read over 2000 channels) and measure the backradiation at the surface. So we know that the physics applies in the real world. If you need links to the satellite images, videos, an online ModTran database (the poor man's HiTran), etc. I can get them for you.
Regarding what to do about carbon emissions, I personally would be interested in an international "Manhattan" project for the development of alternate energy. Richer nations have slower population growth. Some countries in Europe and elsewhere are already experiencing negative population growth. If you don't grow the economy, population growth will and carbon emissions will grow along with it. So in my view at least, you need to find a way to make room for economic development without substantially sacrificing living standards.
Fusion, solar power, wind -- but pool the research and the costs, then make the technology widely available. And we might also want to encourage the development of agrichar/biochar for use in agriculture. Its cheap, enriches the soil raising agricultural production, and more or less permanently (on the scale of centuries at least) sequesters carbon.
Just a thought.
Re: Reads like gibberish
Stephen quotes me, "Finally, of course the essay for this thread deals with the possibility that we have been underestimating the indrect effect of aerosols."
... and then responds, "If what you're trying to say is 'the second part of The Register's article deals IPCC's acknowledgement that the cooling affect of aerosols is not well understood', then ... er, yes."
Stephen, I was thinking of this part of the essay:
"Dividing the atmospheric effect of aerosols into their wet and their dry effects, as the IPCC report does, has been an uncritical assumption so far....
"'We found that the region affected by this cloud field 'twilight zone' extends to tens of kilometers beyond the identified cloud edge. This suggests that 30 to 60 per cent of the atmosphere previously labeled as 'cloud-free' is actually affected by cloud-aerosol processes that reflect solar energy back into space.'"
Cloudy outlook for climate models, http://www.theregister.co.uk/2007/12/27/anton_wylie_climate_models/page2.html
Essentially, this part of the essay is pointing to one piece of evidence missing from the IPCC report, or to be more accurate, what amounts to a matter of degree where the IPCC report viewed things in more qualitative terms. Given the twilight effect, it would appear that rather than having simply dry and wet aerosols, you have dry shading into wet. In any case, what the twilight zone amounts to is a relatively invisible extension to clouds, which given its extent may nevertheless have a significant albedo effect.
Here is another essay which goes into the issue in a little more depth:
May 3, 2007, WIDESPREAD 'TWILIGHT ZONE' DETECTED AROUND CLOUDS
... and if you would like something with still more detail:
Koren, I., L. A. Remer, Y. J. Kaufman, Y. Rudich, and J. V. Martins (2007), On the twilight zone between clouds and aerosols, Geophys. Res. Lett., 34, L08805, doi:10.1029/2007GL029253.
Stephen quotes me, "However, that isn't the IPCC - and if one considers the indirect effect of aerosols through their promotion of cloud formation and albedo, it would probably be wise to include their contribution to the cloud greenhouse effect as well as the greenhouse effect due to aerosols themselves."
... and the responds, "This sentence makes no sense at all. Gramatically, logically, or otherwise. Can anyone translate?"
Increased opacity of the atmosphere to infrared radiation (regardless of whether this is due to gases, aerosols, or clouds) reduces the rate at which thermal energy is radiated from the climate system. If you were to hold constant the rate at which thermal energy enters the climate system, this would mean that the surface must heat up and radiate more thermal radiation until the amount of thermal energy leaving the climate system (as the result of the absorption of sunlight) is equal to the amount of thermal energy entering the climate system. And as a matter of fact, clouds are relatively close to being blackbodies in the near infrared, so they have a relatively strong greenhouse effect.
Clouds have an albedo effect, which means essentially that they reflect sunlight before it has the chance to be absorbed at the surface. However, clouds also have a greenhouse effect associated with them because they are fairly opaque to infrared radiation.
Like greenhouse gases, they will absorb infrared radiation then reemit infrared radiation isotropically, both towards space and towards the surface. The backradiation which they send towards the surface will warm the surface while reducing the rate at which thermal energy is lost to space, hence the additional greenhouse effect.
Now with the twilight effect, aerosols give rise to a largely invisible extension to clouds. This extension is known as the twilight zone. As an extension of clouds, the twilight zone will have an albedo, albeit a diffuse one. This will give rise to cooling. However, being that the twilight zone is an extension of clouds, it will also have a greenhouse effect where it absorbs and emits thermal radiation, with the backradiation which it sends to the surface resulting in further warming.
The net effect? Difficult to say. With clouds at least, the albedo effect and greenhouse effect largely cancel one another out, and even the sign of the net residual is determined in part by the altitude of the clouds and their thickness.
But the albedo effect is likely to be greater than the greenhouse effect. Nevertheless, the greenhouse effect associated with clouds is quite significant: it is the reason why things will tend to remain warmer on a cloudy night than on a clear night. (I remember wondering why it remained warmer on cloudy nights as a child.)
Incidentally, I had also mentioned the greenhouse effect due to aerosols in relation to the Asian Brown Cloud. Here are a couple of stories on it:
August 01, 2007, 'Asian Brown Cloud' Particulate Pollution Amplifies Global Warming, http://www.physorg.com/news105192948.html
Asian Brown Cloud of pollution contributes to global warming, Roger Highfield, 02/08/2007
All in all, I don't expect twilight zones to change the big picture that much. As I pointed out earlier, the original B Scenario projection that Hansen presented along with the A and B, but endorsed as likely to be more accurate before US Congress in 1988 was pretty much on target twenty years later. Uncertainties, approximations and unseen effects typically tend to cancel each other out given the law of large numbers.
Improvements in modeling tend to leave the big picture much the same, merely bringing it into sharper focus. However, this may change some of the details quite significantly, I would suspect that by properly incorporating twilight zones into the models, we will improve modeling most particularly at the regional level.
Re: A simple question
Alan, if I remember correctly, you have an interest in the paleorecord, so I will go into a little more detail in my response to you - using examples that may be of some interest.
Alan Wilkinson writes,
"Water vapour is supposed to be the magnifying factor for CO2 with the argument that more CO2 creates warming that increases atmospheric water content thereby further increasing warming. But this is a feedback loop that doesn't seem to require CO2 at all, since water vapour itself creates warming that increases atmospheric water content thereby further increasing warming ...."
Water vapour feedback does not require carbon dioxide. Remove the carbon dioxide, move the earth a little closer to the sun but give it the same orbital variations and tilt, and you would still have your glacials and interglacials -- although the cooling as you approach the glacials would probably be more rapid and the warming as you approach the interglacials would be slower. In other words, it amplifies the effects of solar incoming radiation (insolation) just as it amplifies the greenhouse effects of carbon dioxide.
Incidentally, carbon dioxide can and does act as a feedback as well, amplifying the effects of other forcings, but it is a "slow" feedback, like ice sheets. With carbon dioxide, the central issue is its residence time. If you inject a pulse of carbon dioxide into the atmosphere, a significant percentage of it will still be in the atmosphere thousands of years later.
So when the climate system is in equilibrium but then disturbed by greater solar insolation due to orbital variations (which are themselves parts the result of our orbit being disturbed by the gravitational fields of Jupiter and Saturn), this raises the temperature of the oceans, reducing their capacity to carry carbon dioxide (and oxygen, by the way), raising the level of carbon dioxide in the atmosphere. Then combined with water vapour, the higher concentrations of greenhouse gases amplify the effects of increased solar insolation.
If one looks at the paleoclimate record, it would appear that carbon dioxide typically acts as a feedback -- amplifying the effects of solar insolation. But there are points in the paleoclimate record where it is clear that what disturbs the climate system is an injection of either carbon dioxide or methane, the latter of which is a greenhouse gas 21 X stronger than carbon dioxide.
Four of the five major extinction events in the history of our planet appear to have begun that way. For example, the greatest extinction event, the Permian-Triassic, appears to have been the result of a carbon cycle forcing due to a Siberian supervolcano releasing large amounts of carbon dioxide into the atmosphere over a period on the order of a million years roughly 251 million years ago.
This would also have been amplified by carbon cycle feedback, including carbon dioxide being released from the oceans, methane being released from shallow water methane hydrates (with some forcing due to methane hydrates melted by the volcanic activity itself), marshes producing methane through organic decay, forest fires, and then a conversion of much of the biosphere into carbon dioxide simply as the result of the extinction event itself.
By the time it was all over, approximately ninety percent of all species living in the ocean had gone extinct and seventy percent of all species living on the land were gone as well -- with a ninety-nine percent mortality rate for the members of the surviving species. This point in the earth's history is sometimes refered to as "The Great Dying," and for a while it would appear that the dominant form of life was fungus. It took several million years for the biosphere to recover.
Regarding water vapour feedback, Alan writes, "So presumably there are natural negative feedback processes that control this very major positive feedback process. How come these are not capable of controlling the much smaller CO2 contribution?"
It is really is a question of residence time.
A fairly significant fraction of carbon dioxide will remain in the atmosphere for tens of thousands of years, but water vapour falls out of the atmosphere as precipitation. Starting with a climate system which is in quasi-equilibrium, an injection of water vapour into the atmosphere raises the humidity, but at the low temperature of the quasi-equilibrium, this simply means higher humidity, increased cloud formation, then additional rain or snow so that the water vapour settles back down to its original level.
The additional moisture will remain in the atmosphere for only a few weeks but for the temperature to rise signicantly as the result of the enhanced greenhouse effect would take decades. In contrast, with carbon dioxide remaining in the atmosphere for far greater periods of time, this limitation (with uptake by the carbon cycle due to plants, absorption by ocean and the much slower process of mineralisation) is far less important.
Incidentally, the greenhouse effect due to carbon dioxide isn't that much smaller than that of water vapour.
Once the peaks of the absorption in the absorption spectra are saturated, the absorption of radiation takes place principally in the wings, and as a result is to a first approximation roughly proportional to the logarithm of the concentration. Thus for the purpose of analysis of their effects upon temperature, it helps to think not in terms of the concentration of the greenhouse gases but in terms of their doublings.
And while those parts of the spectra where carbon dioxide would act in the lower troposphere are already saturated by water vapour, water vapour tends to be limited to the lower layers of the troposphere, and as such carbon dioxide is quite effective in the upper parts of the troposphere, stratosphere and above.
As such, while water vapour amplifies the effects of carbon dioxide, it is by no means proportional to their relative concentrations in the atmosphere. The enhanced greenhouse effect which would result from the direct effect of a forcing by a doubling of carbon dioxide in the atmosphere would be roughly 1.1 C. With all the feedbacks, we estimate it would be closer to 2.8-2.9 C, best estimate.
Max states, "It doesn't matter who they work for; the fact remains that consensus is not proof."
Empirical science doesn't deal in proof. Proof belongs to Euclidean geometry and other mathematical constructs, but because they are capable of proof, we do not know whether or in what way they correspond to empirical reality. The currency in empirical science is testability and the cummulative weight of the evidence. In freshman philosophy one learns that in principle at least it is possible to coherently argue that the world came into existence only five seconds ago without actually contradicting any evidence. All one has to do is claim that whatever evidence of the world's apparent greater age, including one's memories, came into existence at the same time, perhaps as the result of an omniscient, omnipotent god or demon. But for that very reason science can't work that way.
It is always possible to cast doubt on any scientific proposition -- however unreasonable or unjustified such doubt may in fact be. The cigarette industry, particularly Phillip Morris, has made great use of this in the past, arguing that we can't actually prove that there are any ill effects associated with smoking. But of course there were and are. I submit that something similar has occured in the case of the fossil fuel industry. In fact I have pointed to a fair amount of evidence to this effect and resources where you can get more information if need be.
Of course there is also the argument that it will simply cost too much to deal with climate change -- and I believe this is part of the reason why the arguments from the fossil fuel industry get so much play. However, it is worth bearing in mind the fact that the same claim was made with respect to dealing with the problem of CFCs and the destruction of the ozone layer. Industries which manufactured CFCs found dealing with the issue inconvenient and portrayed action on this front as prohibitively costly. Now I have no doubt that the costs associated with dealing with climate change will be much more costly, but whatever the costs, it does not change the actual facts or consequences of climate change, and to deal with climate change we must first recognize it for what it is rather than attempting to deconstruct the evidence by means of extended exercise of cartesian doubt.
The longer we put off acknowledging the evidence for what it is, the more committed we will be to certain paths (such as the replacement of oil use with coal), the more costly it will be to switch to some other path, the less time we will have in which to act, and the more draconian (and perhaps futile) the measures that will in all likelihood be taken for dealing with a problem which for all intents and purposes we will simply no longer be able to ignore. Those who acknowledge climate change for what it is sooner rather than later will necessarily have a greater voice in determining how we respond to it -- as will we all.
Max writes, "realclimate.org folks have a vested interest in maintaining their position, as do many of the other bandwagon jumpers..."
No scientific discipline gets more research money by claiming that all the issues are settled. To the extent that climatologists make this claim, what they actually encourage is the shifting of investment from investigating climate change to the investigation of the means of dealing with climate change, such as alternate energy, bioengineering, or for that matter economics. (Incidentally, I myself am strongly pro- free market, but as identification precedes evaluation, science and the recognition of reality must precede politics and ideology. As a matter of principle, I have no choice in this matter.)
And RealClimate is well within the mainstream of climate science, like the IPCC. As I have noted, every major scientific organisation which has seen fit to take a position on anthropogenic global warming takes what is essentially a consensus view, namely that the evidence for it is overwhelming.
A rather extensive list of links to the statements by these scientific organisations may be found here:
I have argued before that the role of consensus (which is typically tacit rather than articulated -- as this is usually all that is required) in modern science is roughly on par to that of testability. In fact, testability largely rests upon tacit consensus. This is an outgrowth of an interdependence which exists between elements of our empirical knowledge, including scientific theories as well as the division of cognitive labor which necessarily exists in the modern scientific endeavor.
I won't go into either of these two issues in much depth here, but simply refer you to a couple of my extended comments elsewhere.
First, a critique of Karl Popper's Principle of Falsifiability which argues for the view that what science requires is testability rather than falsifiability as the result of an interdependence which exists between modern scientific theories (a slightly modified excerpt from a paper giving critical history of early twentieth century empiricism I did over a decade ago):
Do Scientific Theories Ever Receive Justification? - A Critique of the Principle of Falsifiability
Second, an analysis of the nature and role of consensus in science:
On “Scientific Consensus”
I don't expect you to really look at either of these, but I wish to make them available nevertheless.
Max states, "Please go argue with these folks on a scientific basis, if you harp on their funding I'll know for a fact you don't know what you're talking about."
Already deal with the science.
My first post, this thread's sixth. But after so many flawed papers being put out pretty much by the same list of people time and time again, we need to understand why they continue to be floated, spamming the newspapers with outlandish claims which have no actual scientific basis. People need to be aware of what is going on, particularly since they will often lack the time and expertise to examine each and every "technical" paper put out by the denial industry.
Max, you gave a link to the Inhofe 400 -- a list of "scientists" who presumably dispute anthropogenic global warming. However, the list is composed of numerous scientists who do not actually the basics but who may disagree about one or another detail -- yet had their names added without their consent, scientists who belong to disciplines largely unrelated to climatology (e.g., astrophysics, string theory), and people who aren't actually scientists at all -- including a television-gardener. It is being slowly analysed at rabett.blogspot.com, www.desmogblog.com, scienceblogs.com/stoat and a number of other blogs. No need to go into it in much detail, except to say that it is a good demonstration of how desperate the denial industry is at this point.
As I have indicated, the basis for anthropogenic climate change is quite strong -- every major scientific organisation that has seen fit to take a position on the issue has come down squarely on the side of climatology, and the list of organisations which have done so is quite long.
Dr Stephen Jones writes, "Timothy Chase has written several thousand words here, yet he has failed to address the two points raised by the article."
Middle initial of E? Just curious -- I might be familiar with your work, in which case I believe our understanding of the book Genesis will be quite different -- despite our both finding much value in it.
I will try to keep my response to you short since you seem to value brevity though I am afraid I will exceed your limit.
Stephen writes, "Firstly, the Douglass survey looks at the data output of the climate models themselves. This is welcome, and the kind of auditing one would expect climate modelers to perform on their own work regularly."
And they do in a large number of areas. You can get some sense of this for example from the pdfs for the GCM - Model E in use by NASA GISS:
They point out the flaws, the areas where improvements still need to be made. In fact they are quite open about it.
Stephen writes, "The study finds that the models are contradicted by empirical evidence ... tropospheric models only work at sea level. Chase ignores this."
The paper itself focuses on the tropical troposphere, and actually I dealt with that paper at some length in my first post in this thread, sixth post from the top. Additionally, the models are now extending beyond the stratosphere.
Stephen writes, "Secondly, the IPCC says it has only a "LOW" understanding of the role of particulate matter (ie, aerosols). This is very important, because particulate matter has a "negative" forcing effect: cooling the earth. In the second illustration (I wish it was larger) we can see that the IPCC admits that the cooling effect of particulate matter is as large as the heating effect of greenhouse gas. Chase ignores this, too."
I mentioned as much in my first comment (towards the end) and elsewhere in this thread. However, the uncertainties regarding aerosols have narrowed in the past couple of years. But if for some reason they were stronger than we think, this would imply that they are masking the effects of other more positive forcings, e.g., greenhouse gases, and given the largely exponential growth of the latter, things might be more serious than they already appear. But as I have indicated, I wouldn't worry about that.
Either way, one wouldn't want to use aerosols all that much to deliberately mask the effects of greenhouse gases -- as the reduction in sunlight would result in decreased agricultural production as it became necessarily to increase the levels of aerosols in order to keep up with greenhouse gases. Additionally, due to their acting as nuclei for smaller water droplets, they tend to decrease precipitation and thereby make drought more likely -- which will also tend to decrease agricultural production.
PS to RE:RTFA
You had stated, "In the second illustration (I wish it was larger) we can see that the IPCC admits that the cooling effect of particulate matter is as large as the heating effect of greenhouse gas."
I failed to address that claim. Too focused on aerosols and the length of my post, I suppose.
However, I believe the chart you are thinking of is this:
... which they got from IPCC 2007 WG1 AR4, chapter two.
The forcings for anthropogenic greenhouse gases expressed in Watts per square metre are:
CO2 1.66, CH4 0.48, N2O 0.16, halocarbons 0.34, stratospheric ozone -0.05, tropospheric ozone 0.35, Total 2.94
direct effect -0.5, cloud albedo effect -0.7, total -1.2
... where the total aerosol effect faily to cancel so much as half the greenhouse effect of the greenhouse gases and would fail to cancel the forcing due to CO2.
Now of course, there are the ranges of uncertainty, such that it might be possible that one might not regard the residual of total aerosol forcing and CO2 forcing as statistically significant, but this would still leave the other greenhouse gases. Additionally, the uncertainties won't be additive, assuming one applies Bayesian logic.
Then one must also keep in mind the fact that there are other means of knowing the residual, combined effect independently of our knowledge of the individual effects. For an analogy, this would be much like how one may not know the rate at which water is entering a tub through an inlet or leaving it through an outlet, but can nevertheless know quite well what the rate at which water is accumulating in the tub by the rate at which the water level rises.
Finally, of course the essay for this thread deals with the possibility that we have been underestimating the indrect effect of aerosols. However, that isn't the IPCC - and if one considers the indirect effect of aerosols through their promotion of cloud formation and albedo, it would probably be wise to include their contribution to the cloud greenhouse effect as well as the greenhouse effect due to aerosols themselves. In the latter case, I am thinking of the Asian Brown Cloud that is amplifying global warming in Asia -- roughly by a factor of two.
Hope this helps...
Re: The interesting question is different
There are numerous threads to your post, enough so that they are something of a tangle. So I hope you won't mind if I pick just a few.
When you state that we already have two thirds of the warming from a doubling of CO2, this assumes that the warming is instantaneous, but that assumption is incorrect. The problem with greenhouse gases is that they create an imbalance between the amount of thermal radiation which is entering the system (when sunlight is absorbed) and the amount of thermal radiation leaves the system (given the fact that greenhouse gases are opaque to thermal radiation but transparent to visible light). As long as this imbalance exists, the climate system must warm up until it reaches a temperature which is sufficient for it to emit as much thermal radiation through the ir-opaque atmosphere as which is entering the system. And this takes time, primarily because of the ocean's thermal inertia. (It takes a while for the ocean to warm up and in effect "do its part" in emitting sufficient thermal radiation.)
You speaks of feedbacks and question whether or not they exist, stating specifically at one point, "Either these loops are real or they are not." But there isn't any question as to whether they are real. What open questions still exist are essentially a matter of the relative strengths of various feedbacks, some of which are positive, others negative, and thus what the overall climate sensitivity to a doubling of carbon dioxide will be.
If you raise the level of carbon dioxide, you increase the opacity of the atmosphere to thermal radiation, where the spectral properties of CO2 are quite measurable under laboratory conditions. This will result in higher temperatures resulting in evaporation -- where water vapor is itself a greenhouse gas. This results in a positive feedback.
However, more water vapor will likely mean more clouds, and more clouds generally mean an increased albedo with a reduction in the amount of sunlight which gets transformed into thermal radiation. This is a negative feedback.
But clouds also have a greenhouse effect, and the greenhouse and albedo of clouds roughly cancel one-another out, so that depending upon the altitude and thickness of the clouds, the net effect will be negative or positive. So how much feedback can we expect from the climate system for a doubling of carbon dioxide?
By itself, without the effects of water vapor or clouds, but simply given the spectral properties of carbon dioxide and its distribution in the atmospheric column, we would expect a warming of roughly 1.2 C. However, with the various feedbacks which exist within the climate system, a doubling of carbon dioxide is likely to result in something more like 2.8-2.9 C.
How do we know this? Extensive studies, some dealing with recent climate change, the reaction of the climate system to volcanic eruptions (or rather, to the reflective stratospheric aerosols they emit), etc., others involving the paleoclimate records of the past 420,000 years, etc..
I would recommend the following two papers
Annan, J. D., and J. C. Hargreaves (2006), Using multiple observationally-based constraints to estimate climate sensitivity, Geophys. Res. Lett., 33, L06704, doi:10.1029/2005GL025259.
Royer DL, Berner RA, Park J. (2007), Climate sensitivity constrained by CO2 concentrations over the past 420 million years. Nature, 446: 530-532.
The latter of these two is bringing together results from over 47 different studies.
Both still have a range on them. Annan might go as low as 2.6 C. However, given the uncertainties involved, significantly higher sensitivities are more likely than significantly lower sensitivities.
You ask, "Is the surface station record reliable and robust, so is the hypothesized warming actually happening?"
1. We have atmospheric measurements in the lower troposphere, the upper troposphere and the stratosphere.
2. These are measurements being taken by planes and satellites. The troposphere is warming - just as we would expect.
3. The stratosphere is cooling - just as is predicted by the anthropogenic global warming theory.
4. We are taking measurements of temperatures in the oceans both at the surface and at various depths. These are showing warming as far down as 1500 meters.
5. We are performing measurements of sea level - which has been rising as the result of thermal expansion.
6. We are performing gravitometric measurements of Greenland and Antarctica which are showing net ice loss in both cases.
7. We can witness sea-ice loss in the Arctic which is dramatically accelerating, with a historic sea ice area minima of a little over 4,000,000 km set in 2005, but less than 3,000,000 in 2007.
8. We are seeing the acceleration of glaciers in both Greenland and Antarctica, particularly within the last few years.
9. We are witnessing the rise of the troposphere.
10. We are witnessing the poleward migration of species.
11. We are witnessing the increased intensity of hurricanes due to the rise in sea temperatures.
12. We are witnessing the accelerating decline of glaciers throughout the world except in a few rare cases.
14. We are measuring the rise in temperatures at greater depths in the permafrost.
15. We are seeing the rapid expansion in the last few years of thermokarst lakes.
16. We are witnessing changes in ocean circulation.
17 We are seeing the disintegration of permafrost coastlines in the arctic.
18. We have seen the number of ice quakes in Greenland triple and the melt flow double within a decade.
19. We are getting temperature measurements from countries throughout the world which show the same trends.
20. When we perform measurements using only rural stations, we see almost identical trends.
21. We are witnessing changes in wind circulation patterns around Antarctica.
Yes, I believe the "hypothesized warming" is happening.
Re: Sun is not a constant factor
This is in response to Anonymous Coward.
"Solar activity: http://www.space.com/scienceastronomy/sun_output_030320.html
..not a flat line in sight."
I said "essentially flat." You take a look at sunspots (a proxy for solar activity, where more sunspots is fairly well correlated with greater solar intensity and you will see increasing activity towards 1950, but essentially just standard quasiperiodic behavior since -- which looks quite flat if you do a running ten-year average. That is, unless you look a little more closely -- as there is a slight drop from roughly 1980 forward -- just as the trend in temperature really took off. Much the same is true with a more direct measurement by means of solar irradiance. It falls off when the rise in temperature becomes strongest.
You wrote, "In fact, Mars shows signs of 'global' warming as well, most probably because of solar activity:"
Warming? Yes. Due to solar activity? Not according to the Space article you link to.
From the article at Space:
"In one case, patches of snow disappeared during autumn in the northern hemisphere -- a time when cooler temperatures should have generated accumulations. A huge dust storm that raged in recent months and for a time covered the entire planet may have been responsible, temporarily raising global temperatures."
From an article it links to:
"Dust particles tossed high above the surface are being warmed by the Sun. They in turn heat up Mars' thin and mostly carbon dioxide-laden atmosphere."
Actually there would be a lot of problems with trying to tie "global warming" on Mars to solar output. For one thing, the temperature on Mars was falling during the 1970s even as our global temperature began its steeper climb. For another, there is that pesky solar irradiance.
Global warming on Mars?
5 October 2005
Still, the contrarians look to Mars and even the more distant planets as a means of maintaining that the solar variability is responsible for the warming trend of the past thirty years.
See for example "Larry King: Bill Nye vs. Richard Lindzen," http://www.youtube.com/watch?v=McsZ1U20W0M
... however, all of these are quite explicable as well.
Please see: Hot times in the Solar System, http://illconsidered.blogspot.com/2007/04/hot-times-in-solar-system.html
Given how remote the distant planets are, with Pluto for example being roughly 30 times as distant from the sun as the earth and with solar irradiance being inversely proportional to the square of the distance, to explain a rise in temperature of a couple of degrees out there by means of an increase in solar output would require levels that would render our planet virtually uninhabitable.
Re: Did I miss something BIG ? Yellow big ?
greg wrote, "There's something annoying about all the climate problematic, from a stupidly basic fact... Where's the sun's changes influences taken in account ?"
I strongly suspect that the sun hasn't entirely escaped the attention of the entire climatological profession for the past century.
Actually, according to a variety of studies the sun has been essentially flat since about 1950, and best estimates given by the Nasa GISS, it would appear that forcing due to well-mixed greenhouse gases has been greater than any positive solar forcing virtually every year since 1880 — with the one exception being that of 1881.
Please see the graphs at:
Forcings in GISS Climate Model
… as well as the data at:
Global Mean Effective Forcing (W/m2)
Incidentally, the data for the levels of various gases, aerosols and the like are obtained independently of models -- and the same models with the same physical equations and code get applied to understanding paleoclimates, e.tc.. You can't really just tinker with them to make them fit as an exercise in curve-fitting -- as a tightening of the fit in one area would result in a loosening of the fit in a dozen others. However, when the fit is bad in a particular area, you can look to see what physics is missing, incorporate it, and chances are the fit in that area and several others will become considerably tighter. They are a work in progress -- but they have already progressed quite a bit.
They seem to be doing a rather good job of making predictions. Not simply in terms of the trends in global temperature, either. They predicted the cooling of the stratosphere, polar amplification where the Arctic latitudes would warm more rapidly than the lower latitudes, the fact that nights would warm more rapidly than days and winters more rapidly than summers. They predicted the expansion of the Hadley cells which govern the extent of the tropics.
They predicted the super greenhouse effect in the tropics where backradiation from the clear sky climbs more rapidly than thermal radiation from the surface as the surface warms above 30 C. They do quite well in describing ocean circulation - and have since 2000. They show, for example, changes in ocean circulation resulting from land warming more rapidly than ocean which result in growing deadzones off the US west coast. They predicted the expansion of the range of hurricanes and cyclones (e.g., Catarina, the first recorded South Atlantic tropical cyclone in 2004 and Gonu in the Arabian Sea in 2007).
They are tested using paleoclimate records and hindcasting. And Jim Hansen's Scenario B (one of three scenarios presented before the US Congress in 1988 made using single runs of a fairly primitive model by today's standards, the one scenario which he stated was most realistic at the time) was pretty much dead-on in terms of predicting the trend in global average temperature -- for the next twenty years.
Re: Pot, meet kettle
Ashley Pomeroy quoted me,
"'Nice ad hominem. (dot dot dot) Every one of the authors is closely associated with at least one organization that is receiving funding from Exxon. (etc)'"
... then responded,
"Apart from being an ad hominem attack in itself, ..."
As I said, "However, I didn't want to bring this up in my first comment (although I hinted at this issue in the title) because one really should address the facts and the science first -- before getting into issues of possibly systematic dishonesty and questions of motive."
You deal with the facts and the arguments first, then you turn to questions of honesty and motive. If this weren't valid, any time you questioned someone's honesty or examined the possibility that they might be engaged in a form of deception you would be guilty of engaging in a logical fallacy. But obviously there are times when it is appropriate to consider issues of honesty. I examined the science and the arguments -- although not in the depth that I would prefer. However, you can look up more at www.realclimate.org -- if you wish. They have a search box.
Ashley Pomeroy continues,"... that's an extraordinarily vague accusation. Are there any employed people in the first world who are not 'closely associated with at least one organisation that is receiving funding from Exxon'? That would include people who drive cars, people who own anything that is made out of plastic, and people who wear clothes."
I am not speaking of anyone who has bought gasoline within the past 50 years. I said "closely associated."
Let's consider Fred Singer for a moment:
1. President, The Science & Environmental Policy Project. Documented funding from Exxon since 1998: $20,000.
2. Editorial Advisory Board Member, Cato Institute. Documented funding from Exxon since 1998: $110,000.
3. Advisory Board Member, American Council on Science and Health. Documented funding from Exxon since 1998: $125,000.
4. Adjunct Scholar, National Center for Policy Analysis. Documented funding from Exxon since 1998: $465,900.
5. Research Fellow, Independent Institute. Documented funding from Exxon since 1998: $70,900.
6. Former Fellow, Hoover Institution. Documented funding from Exxon since 1998: $295,900.
7. Former Fellow, Heritage Foundation. Documented funding from Exxon since 1998: $585,000.
8. Former Fellow, The Advancement of Sound Science Coalition. Documented funding from Exxon since 1998: $30,000.
9. Adjunct Fellow, Frontiers of Freedom. Documented funding from Exxon since 1998: $1,037,000.
10. Speaker, Centre for the New Europe. Documented funding from Exxon since 1998: $170,000.
11. Expert, Heartland Institute. Documented funding from Exxon since 1998: $791,500.
12. Contributing Writer, Weidenbaum Center. Documented funding from Exxon since 1998: $120,000.
13. Contributing Writer, Federalist Center. Documented funding from Exxon since 1998: $90,000.
Grand total documented funding of organizations that Singer is associated with by Exxon since 1998:
Incidentally, I got some of this information from:
... but most of it is from the link I provided earlier:
Singer has quite a history -- as his entry in Source Watch attests to. So does Christy:
The other authors don't have a writeup on SourceWatch as of yet, though. But Douglass has coauthored other equally flawed pieces with Singer and Patrick J. Michaels (another Exxon superstar) on a number of occasions.
The scientific case for our understanding of anthropogenic global warming is quite strong. If you haven't the time to learn about all of the science yourself, you may want to examine the statements by scientific bodies in this matter.
Every major scientific organisation which has issued a statement in this matter has come down on the side of climatology. In large part it really is just a matter of physics -- despite the complexity of the climate system.
However, I would recommend learning as much you can -- if it at all interests you. From what I can see there is a fair amount at stake in the coming decades, particularly in terms of our coastal cities, agricultural production and water supplies. If we continue along our current trajectory, the loss of life and effects upon the world economy in the latter part of this century looks to be quite substantial.
A Response to that Anonymous Coward...
Under the subject of "Co-ordinated Real Climate spam?", Anonymous Coward writes:
"The AGW supporters must be seriously worried.
"'Real Climate has not done a piece on this particular development.'
"Yet it has - the 'Real Climate' blog gets three links in the first half dozen posts..."
I was refering to the subject of the twilight zone of clouds, not the tropical troposphere. It helps to read the sentence immediately preceding that one in the same paragraph.
"Have these Global Warming bloggers been waiting up all night - in their pyjamas - simply to whack any media organisation that reports Douglass et al?"
Nice ad hominem.
Real Climate goes quiet from about 4:00 to 12:00 GMT, give or take. I myself scan the news periodically throughout the day, just looking for new stories or new news on old stories.
For example, there is the thinning of the Arctic ice that, best estimate, will be gone during the summers by 2013 or earlier even though the models were projecting something more like 2050 or perhaps well into the 2100s. They seem to have underestimated some of the positive feedbacks, most particularly oceanic advection -- due to the low resolution of the models.
Then there is the increased saturation of various carbon sinks where for example parts of the major oceans including the Southern Ocean are proving less able to absorb our carbon emissions, although another major sink which is becoming less effective includes plants, at least during the warmer, drier years. Then there is the record melt in Greenland, news from the Antarctic Peninsula (both Greenland and Antarctica are losing mass now -- with the trend in Antarctica having been reversed within the past few years), etc.
Anyway, climate news has been a little slow with the holiday season, and this post at the Register came up -- so I thought I would check it out.
Anyway, I suspect you are right about spam being involved -- you simply misidentified the culprits and the intended targets. Every one of the authors is closely associated with at least one organization that is receiving funding from Exxon. Singer, Douglass and Christy belong to the Heartland institute -- which has received well over half a million US dollars within the past decade, for example. Singer is actually associated with thirteen organizations that have received funding from Exxon. Pearson is the odd man out, as he belongs to only the Atlas Economic Research Foundation -- brainchild of someone fond of Ayn Rand's "Atlas Shrugged," no doubt. I would expect him to be a bit more ambitious.
Anyway, feel free to check:
It gives you the names of the organizations, the manner in which the funding was funneled, links to material on the authors, etc. However, I didn't want to bring this up in my first comment (although I hinted at this issue in the title) because one really should address the facts and the science first -- before getting into issues of possibly systematic dishonesty and questions of motive.
Before climate change, my personal obsession was with evolutionary biology and the attempt by creationists to achieve a more "balanced treatment" of the subject in the schools, that is, use the school systems to indoctrinate students - and get children to chalk up modern science to some sort of ideological conspiracy. However, I suspect there may be a bit more riding on the issue of climate change at this point, so I switched.
In all honesty I prefer studying the role of viruses and various retroelements in evolution over climatology. But we must all do our part, I suppose.
Nice attempt by the Greenhouse Gas Defence Team
The paper by Douglass, Pearson, Singer and Christy was recently analyzed at Real Climate, a blog run by climatologists including Michael Mann (a paleoclimatologist who is known for the original hockey stick diagram) and Gavin Schmidt (who worked on the most recent global climate model for NASA GISS). The conclusion that the authors arrive at, namely, that greenhouse gases are not what is primarily responsible for current warming -- is entirely untenable -- even if one were to find that the rest of their paper were largely or entirely correct. The reason being? We have a great deal of evidence that global warming is being caused by greenhouse gases.
For example, they increase the opacity of the atmosphere to infrared radiation, raising the temperature at the surface while reducing the amount of thermal radiation which reaches the stratosphere, hence cooling the stratosphere. Increased solar radiation would raise the temperature both at the surface and in the stratosphere. Likewise, warming will be greater at night and during the winter under an enhanced greenhouse effect as night and winter are more dependent upon the process of thermal radiation given increased atmospheric stability and thus reduced heat loss due to convection. All of these effects have been measured and are individually quite difficult to explain without reference to greenhouse gases.
Furthermore, our understanding of the role of greenhouse gases in warming the climate is built upon a solid foundation of physics, particularly radiation transfer theory, and more fundamentally, quantum mechanics. We can virtually derive their absorption spectra from the first principles of the latter. We can observe the thermal radiation which they give off at different altitudes at different parts of the spectra by means of satellites capable of watching well over two thousand spectral channels. We can measure the backradiation with which they heat the surface at the surface itself. We can even image the infrared emissions of carbon dioxide as it drifts away from the heavily populated west and east coasts of the United States at an altitude of 8 km -- because of the increase in the opacity of the atmosphere to infrared radiation given the higher CO2 concentrations.
At best, assuming the paper was otherwise flawless, the only conclusion which the authors might have right to derive would be that some of the details regarding the modeling of the tropical troposphere -- perhaps involving moist air convection -- require more work. We might conclude that one has to increase the model resolution in order to properly capture the process of convection at work, perhaps. However, as it is, the paper was deeply flawed.
They did not properly take into account model uncertainty -- and they completely omitted any analysis of the observational uncertainties inherent in the radiosonde product they used for validating the models. But what is worse is that is that they used a version of that product that was out of date. They used RAOBCORE v1.2, whereas the most recent version is 1.4. By simply using the more updated version of RAOBCORE and two standard deviation ensemble model uncertainty, the RAOBCORE product's curve for the tropics is well within the envelope of uncertainty associated with the models. And in fact, this is essentially what was concluded by a far better paper earlier this year:
Thorne, et al (2007), Tropical vertical temperature trends: A real discrepancy?, Geophys. Res. Lett., 34, L16702
For the Real Climate review of the paper by Douglass et al on the tropics, please see:
Tropical tropospheric trends
12 Dec 2007
With regard to the discovery of the twilight zone around clouds, I personally find this exciting. Clouds and aerosols are the two largest sources of uncertainty left in the models -- and I suspect that it will lead to considerable improvements in regional modeling. However, readers should keep in mind the fact that clouds have both an albedo effect and a greenhouse effect associated with them, and these two effects largely cancel one-another out -- with the sign of the net, residual effect being largely dependent upon the altitude and thickness of the clouds. However, as of yet, Real Climate has not done a piece on this particular development. I am hopeful that they might remedy this at some point in the weeks to come.