Climate models appear to be missing an atmospheric ingredient, a new study suggests. December's issue of the International Journal of Climatology from the Royal Meteorlogical Society contains a study of computer models used in climate forecasting. The study is by joint authors Douglass, Christy, Pearson, and Singer - of whom …
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.)
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.
Science vs spin
Science can collect data and assimilate them. It can form hypotheses as to causal relations and often it can set up experiments to falsify them. 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. Two clocks showing the same time may or may not be causally connected, either directly or remotely.
Spinners can collect data from science and extrapolate them portraying them as scientific predictions and can portray scientific hypotheses as scientific truths. Spinners use the word 'science' as a cudgel (argumentum ad baculum) to beat their messages into the minds of the innocent.
We must always be alert and make sure that what we are being told is science and not fiction. The easy way to tell the difference is the degree of confidence attributed to the assertions - science cannot commit to any certainty whatever - the spinner will claim 'virtual certainty'.
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.
Water vapour sensitivity
It doesn't matter if the earth takes a long time to respond to small increases in atmospheric water vapour. It has had a very long time to do so - more than enough if it was going to.
Clearly it is held in check by delicate balances involving huge convection systems of both air and water; temperature, pressure and gravity gradients and cloud seeding factors. The resulting distribution of clouds and temperatures also affects the radiation balances.
The critical question is whether these balances are sensitive to CO2 and if so to what extent.
Despite your confidence the immediate historical record of temperature change is not a clear correlation with CO2 levels at all. The ending of the mini-iceage and the temperature decline for 3 decades after WW2 muddy the water considerably. The paleoclimate evidence requires even more circumspection regarding its assumptions, accuracy and consistency.
Neither are the model predictions the unmitigated success you portray. There are a number of interesting papers here discussing important inconsistencies in the models compared with actual observations:
Uncertainties about clouds, ice and circulation patterns play large roles according to these and other papers. The deviations from predicted temperatures are significant relative to the small size of the CO2 warming effect as are deviations between the various models themselves.
Yes, there are reasons to believe CO2 may have a warming effect and that the earth is currently on a warming trend. Quantifying both is a different matter altogether. Consequently deciding what interventions if any are justified by the science is equally problematic.
Disappointing responses from Mr. Chase
Ten days have now elapsed since I invited Mr Chase to address two of the article's main points in 200 words or less.
1 - The study finds that the models are contradicted by empirical evidence ...tropospheric models only work at sea level
2 - The IPCC says it has only a "LOW" understanding of the role of particulate matter, and that the cooling effect of particulate matter is as large as the heating effect of greenhouse gas.
Mr.Chase has now posted 30,000 words in response: almost all of it irrelevant to the points questioners have raised.
Therefore I see nothing to contradict the Mr Wylie's conclusion that -
"on both empirical and inferential grounds, then, the science of climate looks to be far from over."
When I am called upon to mark student papers, I look for relevance and logic - there is very little of either from Mr Chase. I would mark this as a "fail".
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