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* Posts by Alan Wilkinson

48 posts • joined 29 Dec 2007

Arctic ice refuses to melt as ordered

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Alan Wilkinson

GW neq AGW

John Foster

As far as I can see the "little ice age" ended around sixty years ago for reasons that can't be attributed to AGW but were almost certainly "natural".

Then we had a period of cooling followed by a period of warming followed currently by a flat or cooling intermission. What comes next seems at best uncertain.

Yes, turning grass and forest into concrete and increasing CO2 is going to have some effect on climate but how significant that is compared with the natural forces and regulatory systems is simply unknown. Given the inadequacy of data and theory present climate models are little more than speculation and their track record is poor.

As a scientist, global warming is something you measure, not something you believe in.

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Alan Wilkinson
Linux

@Vendicar Decarian

AGW believers, AGW denialists - neither terms have anything to do with science; politics and psychology maybe.

Science is about discovering the unknown, not worshipping the supposedly known. Some humility and an open mind goes a long way. Absence of both is little recommendation. Neither are bad manners.

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Alan Wilkinson
Linux

@vendicar decarian

It's pretty obvious that AGW is not Vendicar's major problem.

Since RealClimate is obviously your spiritual and emotional home, Vendicar, why don't you go back there instead of insulting and ranting at every other poster here? Whatever that is, it isn't science.

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Alan Wilkinson

@Vendicar Decarian

NASA/GISS/Hansen/Schmidt are "whipping boys" not because they refuse to be gagged but because they are fanatics, take extreme positions and denigrate all contrary evidence and other scientists. The GISS temperature record has been fudged, modified and discredited repeatedly, the latter most notably by climateaudit.org. They do not agree with the two satellite record series and they invariably err on the side of greater warming.

The climate models lack adequate data to test and validate them. We do not understand natural climate variations sufficiently to distinguish current trends from them. The estimates of their likely accuracy lack any plausibility. The critical behaviour of clouds is a fundamental uncertainty that strikes at the heart of the assumed positive amplifying feedback that the models portray.

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Alan Wilkinson

Oops

Sorry, typo - "change" should be "chance" in last para.

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Alan Wilkinson
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Concerted attack?

A concerted attack of uninformed twaddle on Steve here.

If you don't want to read about global warming - or the lack of it - just go somewhere else and stop wasting our time with inane comments.

NSIDC is itself talking about extent of sea ice, not volume or thickness. All those criticising Steve for doing the same should stand up and apologise - fat chance I expect: http://www.nsidc.org/arcticseaicenews/

Short of dispersion as pack ice rather than as a solid crust it seems a very remote possibility that volume will not increase with area. And an even more remote change that the AGW industry would not be trumpeting the fact.

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Are the ice caps melting?

Alan Wilkinson
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@Cheevy

<i>Funny how people seem to argue we should be wasting our resources because they don't believe in global warming.</i>

The exact opposite. We believe we should not be wasting huge resources on meaningless GHG reduction strategies because global warming is demonstrably NOT happening whether we believe in it or not.

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Flirty texting could land Scots in jail for 10 years

Alan Wilkinson
Stop

Being offensive is natural, not a crime

More garbage legislation. Offending people is not a crime. Hurting or damaging them or their property is. These do-gooders need to be told where to stick their daft laws.

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Windows XP SP3 sends PCs into endless reboot

Alan Wilkinson
Unhappy

Not just AMD problem

I got exactly these symptoms (boot fails and restarts continuously unless booted in safemode) on a bog standard Thinkpad A61p with an Intel chip.

So there are either several different problems with the same symptoms or it is definitely not localised to AMD machines.

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Global-warming scientist: It's worse than I thought

Alan Wilkinson
Alien

Some of these comments!

Ice floating in water does nothing to the water level when it melts!

If the sea expands when it gets hotter, so does the land! It will make no difference (actually, most likely the land will expand a bit more and get higher).

Unfortunately Hansen/Schmidt/GISS/RealClimate are fanatics first and scientists second. Handle their statements with a very long barge pole.

Greenland was hot enough to support a population of up to 3000 Viking farmers for three centuries in medieval times. There are no reports of London being under water due to consequential sea level rise during that period.

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Terry Pratchett donates £500k to Alzheimer's charity

Alan Wilkinson
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Great man, good wishes

To be able to give, you first have to earn. And usually to earn a lot you also have to give a lot.

So Patchett is giving twice over and I wish him and all sufferers of horrible illnesses all the very best.

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Terrorist robots dissected - anatomy of a scare

Alan Wilkinson
IT Angle

Kiwi Cruise Missile

Bruce Simpson is alive and well, not in cuffs and still running his current affairs website, Aardvark Daily, despite his cruise missile project.

As others have said, the main terrorists are the bureaucracy-industrial complexes that convert terror->taxes->useless countermeasures->personal gain. These people kill infinitely more citizens and waste infinitely more money than any real terrorist attack. They just do it much more discretely generally - though GW Bush is an exception.

The real fallacy is that most terrorists want to create terror. They don't, they think that terror is the route to what they really want. By far the best defence is to change that thought. The truly psychopathic fringe is then be shorn of any support and we only need solutions that deal with individual lunatics or criminals and the smaller level of risk they pose.

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Boffin: Coconut jumbo is millstone in disguise

Alan Wilkinson
Happy

Lye is useful

A small chemical point. If Lye (NaOH) is a byproduct of hydrogen production by electrolysis of sea water it can be used directly for carbon dioxide sequestering. So you would get two benefits for the price of one.

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Alan Wilkinson
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Good to see my profession exposing claptrap

Good to see professional chemists exposing the blatant fraud and ignorance surrounding present Kyoto initiatives.

Matt, you missed everything. You must be determined to.

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Die for Gaia, save the planet?

Alan Wilkinson

Good article and some ridiculous responses

It's a while since I've read so much emotive twaddle in response to a perfectly reasonable send-up of anti-scientific stupidity.

Yes, the planet's resources are limited. But our ingenuity in the ways we use them are not - or at least there is no indication we are anywhere near a limit.

Urbanisation has been called the great contraceptive. Economic and technological development inevitably lead to population control.

The great Global Warming scare is vastly over-hyped as far as present knowledge of our planet's surface systems can foresee - actually we can't forecast even to within an order of magnitude. All we have is a series of scary "what if" questions but no answers.

And since we don't know how things work we can't understand the problems and we certainly can't fix them. All we are likely to do is make things much worse via huge amounts of wasted money and counterproductive nonsense like the biofuels fiasco and the carbon offset and carbon mile frauds.

Not to mention such pathetic pseudo-scientific claptrap as P x A x T - or indeed the ludicrous argument that Hong Kong survived because of the New Territories.

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'Suspicious comment' provokes LAX terminal evacuation

Alan Wilkinson
Unhappy

The morons are in charge

We put morons in charge of our lives and they employ idiots to carry out their orders. Why is anyone surprised at the results?

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Big Climate's strange 'science'

Alan Wilkinson

Results are what matter

Scott, I agree the results are what matter. My problem is that we are not able to forecast those results to better than within a factor of five at the most optimistic view (ie that the models have no fundamental deficiencies).

To assist our education, please show us evidence that we know what is happening with sufficient precision to have any clue as to what we need to spend money on. No-one else has.

The global average temperature charts have been flat for a decade. Please pontificate further.

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Alan Wilkinson
IT Angle

Show me a model with predictions

I notice on reading this that everyone who claims experience with mathematical models is sceptical and that is also my position.

Please show me the best existing climate model and its verifiable predictions matched to data and expected errors in those predictions over the next decades and century.

Then we can see if anyone here actually knows what they are talking about.

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Scientists warn on climatic 'tipping points'

Alan Wilkinson
Stop

Sign off

Saddam Hussein also found people who agreed with him and was pretty good with stuff like cyanide too, Mark. It didn't make much he said right or useful either. I'll leave you to your opinions and unpleasantness.

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Alan Wilkinson
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Oh Dear

Now you are just being plain stupid as well as rude, Mark. CO2 absorbs IR. It also radiates it and disperses it via molecular collisions so that it becomes a transport medium.

I don't wrap up in winter with a material that is constantly convecting and interacting with a much denser "insulator" (water vapour) that is also circulating, forming cloud barriers to incoming radiation (my warmth is generated internally, not externally) and in very complex dynamic equilibriums with huge variations in temperature from place to place and time to time.

The amount of CO2 warming is small compared with water vapour. To have a significant GW effect it needs a multiplier deduced from a secondary positive feedback impact on water vapour concentrations. But we don't properly understand the negative feedback systems controlling water vapour, clouds, precipitation and temperature. Hence caution.

A fool never knows what he doesn't know. And I haven't learnt anything useful from your posts yet.

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Alan Wilkinson

Lonesome Mark

It's a bit sad to see Mark on his lonesome here with hardly an argument to stand on except CO2 absorbs IR. So does water and a heap of other things - in fact pretty much every molecule that has vibrational quantum states. I may have spent more time working with IR spectra than you have, Mark.

The big question is how our atmosphere controls water vapour content through convection and precipitation. And it is not one that has a simple answer - certainly not yet. Until we understand that we are nowhere near having predictive capabilities.

I am not sure who Mark is (are there two?) or who he is calling a troll but it certainly doesn't inform any debate nor have any place in science.

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Alan Wilkinson

Re: What would be firm evidence, Alan?

1. A model that doesn't require significant twealing every time a new piece of data is obtained or when yet another year without significant average warming passes.

2. A predictive ability that produces confidence in its estimate to within a small percentage of the predicted warming factor rather than one so large that the prediction is worthless.

3. A solid understanding of cloud and convection formation and behaviour including both the reflecting and insulating effects of clouds and precipitation thereby improving our understanding of the critical atmospheric water vapour balance.

4. A better understanding of polar ice behaviour patterns.

5. A better understanding of soil and ocean carbon cycles.

6. Better technologies for carbon sequestering at source as well as by enhancing and protecting natural absorption cycles.

7. Better understanding of the cosmic and solar radiation cycles and their impacts and interactions with the earth and its atmosphere.

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Alan Wilkinson
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Re: Wasting money means people die

"And with AGW we don't have any evidence that that money is wasted."

That's already nonsense and will become more so as the vast bureaucratic industry based on Kyoto cranks into gear.

I already said what we should be doing and am quite prepared to defend that against anyone - or more to the point listen to and consider criticisms objectively and rationally.

Speculating on solutions ahead of firm evidence is a job for private investors, not for Governments with other peoples' lives and money.

Clearly the science is not settled and the debate on both sides degenerates far too quickly into propaganda and personal attacks. In my opinion both Gore's film and the "Great Global Warming Swindle" opposition are polemics that cherry-pick rather than illuminate the facts.

As I said before, from what I have seen of it I think climate science is at the stage where it can raise serious questions but not answer them. I believe good knowledge will eventually come out of it and good solutions will be found for the problems that turn out to be real but I do not think we can identify sufficiently either the problems or the solutions for them at this time. I am sure the current implementations around Kyoto will do much more harm than good.

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Alan Wilkinson

Wasting money means people die

Mark, wasting money on ineffective actions and corrupted remedies will also cause people to die.

The misconceived biofuels disaster has already caused that by diverting food production to fuel production.

Nothing I have seen says Kyoto will fix anything, yet it will cost billions which could have been spent on doing directly useful things like feeding people, taking remedial action to adapt to any changes that are affecting peoples' lives, R&D for carbon sequestering and for new energy systems. Kyoto will be manipulated by governments and businesses for their own purposes as is already happening. I expect most of the offsets will be ineffectual shams and the biggest contributors will be shielded and immune.

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Alan Wilkinson

Questions are not Answers

IMHO the current state of climate change models enables them to raise serious questions but not to answer them. The state of knowledge and quality and range of data available to test them is simply insufficient.

As evidence of that, one of the latest and supposedly best refined models adapted to current data I am told is DePreSys. Eg:

Improved Surface Temperature Prediction for the Coming Decade from a Global Climate Model

Science, Aug 10, 2007, Doug M. Smith, et al

http://www.heatisonline.org/contentserver/objecthandlers/index.cfm?ID=6557&method=full

Note the conclusion: "the year 2014 predicted to be 0.30° ± 0.21°C [5 to 95% confidence interval (CI)] warmer than the observed value for 2004."

In other words, the predicted ten year warming is in the range 0.09°C to 0.51°C with 90% confidence in the estimate. But of course this error range does not include errors due to fundamental deficiencies in the model. It is merely calculated on the scatter the model produces when initial conditions are randomly tweaked. So at the very best we are told the model has an uncertainty in its ten year predictions of a factor of five.

Extrapolate that to 100 years and the uncertainty can only increase.

Furthermore, most science I have seen uses 95% confidence levels. Why not here? The obvious answer is that if the authors gave the error range for the usual 95% standard it would not exclude the possibility that the ten year warming outcome would be zero.

As far as I can see the history of Viking farms in Greenland does in fact seriously question the doomsday scenarios regarding its melting icecap.

Eg, see: http://www.nytimes.com/2001/05/08/science/08VIKI.html

Greenland was occupied by settlements of up to 1500 people for four centuries until about 1350 during much of which they farmed cows and sheep. The claim that they were supported during that time only by supplies from Scandanavia seems untenable.

There are no reports that London was under water during that period.

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DHS official moots Real ID rules for buying cold medicine

Alan Wilkinson
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More madness

This is why US tourism has dropped 20% while everywhere else is up 20%. And why I won't transit North America until Bush and his madness are long gone.

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Sir Edmund Hillary dies at 88

Alan Wilkinson
Stop

Trix is right

Trix is right. And it doesn't matter anyway. The partnership was what mattered, what created the success and what strengthened after it into an enduring friendship between Hillary and Tensing, Nepal and New Zealand. We did it together. We are prouder and stronger together. To divide this achievement would simply weaken it.

But the rumors being quoted here are simply wrong. Hillary happened to be at the front on the final segment. Perhaps that was a result of the subtle racism of the time anyway - who knows. But Hillary was anyway sensitive to it and according to other accounts never varied from his policy of saying they reached the summit together until after Tensing himself revealed the secret in his autobiography.

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Alan Wilkinson
Thumb Up

Ed Hillary showed what to do with fame

Another Kiwi reading El Reg, another in awe and admiration of Ed Hillary. I think he ranks with Nelson Mandela as a very great human being we are so happy and proud to share with the world.

He was a man to challenge and inspire all of us to aspire higher and do better - and ignore all the B.S and get on with what really matters.

R.I.P., Sir Ed - your life was well and truly lived and fulfilled.

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Cloudy outlook for climate models

Alan Wilkinson

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:

http://www-pcmdi.llnl.gov/wgne2007/presentations/

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.

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Alan Wilkinson

Einstein had it right!

Timothy, I quote Einstein when a book was published called "100 authors against Einstein". He said, "If I were wrong, one author would have been enough". I think your latest post weakens your case rather than strengthening it.

Consensus means little. Disputed consensus means even less.

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. That he eventually relinquished his position in order to work full time in social work for his Church enhanced his humanity and integrity in my eyes. Likewise Spencer seems to conduct himself with dignity and rational discussion in the face of some vicious ad hominem attacks and sneers.

His comment about the self-correcting nature of our weather was plainly a speculation but surely a reasonable one, 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.

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.

Frankly, a lot of your argument has been fluff. If your best climate model today predicts a temperature rise over a decade that is only microscopically different from zero this is not something you can just choose to ignore and dismiss as only one aspect of climate change. It is fundamental.

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. 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.

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.

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.

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Alan Wilkinson

'Greenhouse'

The reason for my quotes around "greenhouse" gases is simple science - greenhouses heat up because of lack of convection, not because of selective radiative absorption. "Greenhouse" is really an emotive misnomer applied to AGW.

I think it is more helpful to think of the atmosphere as an insulating layer around the earth but it is a peculiar insulation that has very mobile holes in it that vary in place, time and effectiveness selectively for both sunlight absorption and radiation heat loss.

We understand the science of static systems but applying it to such mobile and interacting complex multi-state systems is a whole different ballgame. 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.

For example as an organic chemist I spent years measuring and analyzing infra-red absorption spectra of various molecular components. That doesn't mean I can make better deductions about their contribution to AGW than Timothy who has not.

Humility goes a long way, but unfortunately is not a successful strategy in politics - and that is where AGW finds itself now.

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Alan Wilkinson

Predictive uncertainties

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.

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.

I think anyone who claims the science is settled doesn't understand the issues.

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Alan Wilkinson

Water vapour sensitivity

Thanks for the interesting discussion, Timothy.

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.

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Alan Wilkinson

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.'

No, this is not constrained to be a geometric series - it is the basis of any monotonic series generator which may tend to a limit or not. In this case there is no indication of an intrinsic limit based on the simple physics. Increasing temperature will increase the water vapour content of the atmosphere. Increasing atmospheric water vapour will increase the "greenhouse gas" effect. The AWG hypothesis depends on exactly these unconstrained factors in arguing for a magnifying effect of CO2 by water vapour.

Residence time of water vapour is a consequence of other control factors, it is not a cause.

It seems a lot more logical to understand this in the form of global precipitation feedback circuits as per Roy Spencer than to talk about short-lived pulses. After all, temperatures, humidity and convection are hugely non-homogeneous around the world at any instant in time as well as from time to time.

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Alan Wilkinson

Re - falsification or testability of climate models

Timothy goes to some length to establish the wide range of physical laws that are incorporated into the climate models and their well-established veracity.

But that was not my concern - mostly my fault for excessive brevity.

My concern (and I suspect this could concern most scientists not intimately familiar with the climate models) is not whether the laws are valid, but whether their representation, weighting and application in the models is adequately consistent with reality, and whether in the course of ensuring that these models accurately reproduce existing data, assumptions, parameters and choices have been inserted that may not be generally valid. Effectively the model design and adaption can create degrees of freedom and properties not properly testable with current data.

There's not much more I can say about this except the obvious point that the more testable predictions can be made from the models over wide ranges of environmental conditions, the better the confidence there will be.

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Alan Wilkinson

Imbalance

Hi Svein, I'm not a climate scientist, just a layman with an enquiring mind who used to be a scientist for a short time 30 years ago. (Also a nocturnal kiwi courtesy of our timezone differences - hence strange posting delays and clusters.)

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.

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Alan Wilkinson

Averages versus actual temperature distributions

Mark, my point wasn't about the difficulty of using polynomials, it was about the necessity of knowing the correct distribution of extremes in order to do so. Global warming is about small differences between large numbers so accuracy is important. Averages don't suffice. Timothy's response about the modelled grid and multiple "random walks" through the starting conditions better addresses the issue.

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Alan Wilkinson

Clouds: Chicken vs Egg

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

Global cloud coverage decreased by 4% 1984-2000: http://www.cosis.net/abstracts/EMS05/00213/EMS05-A-00213.pdf

This period coincides closely with a strong global warming phase. Which is cause and which is effect?

See also http://preview.tinyurl.com/yrva4d for further exposure of the chicken and egg question and the link in it also elaborating on aerosol impacts:

http://climatesci.colorado.edu/2007/08/13/important-new-paper-on-the-role-of-aerosols-on-regional-and-global-climate/

Finally, this is a good, readable summary that appeals to me in logic and tone:

http://www.weatherquestions.com/Roy-Spencer-on-global-warming.htm

It includes these paragraphs which seem to me to be at the crux of the question I asked and which at this time of posting has not been answered adequately IMHO:

"1. All climate modelers must build their models based upon our current understanding of how the climate system works. Therefore, if there is some important - but as yet poorly understood - process that they are missing, they will all tend to make the same error. Past evidence for this is the tendency for climate models to drift away from a realistic climate over time. This suggests that it takes a higher level of understanding to capture the intricate processes that stabilize the climate system.

2. 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."

I hope Timothy will continue to respond as I appreciate the opportunity for informed rational discussion.

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Alan Wilkinson

Re - falsification or testability of climate models

'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.'

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.

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.

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Alan Wilkinson
IT Angle

Atmospheric half-life of CO2

The total mass of global atmospheric CO2 is 3000 Gigatonnes. The annual CO2 exchange is around 800 Gigatonnes. Therefore half of the CO2 is recycled every 3.75 years.

The residency argument is an argument that natural sinks cannot cope with any additional CO2 except by conversion to carbonate minerals through a very slow process. It is not actually an argument about the residency of global CO2 but about the persistence of additional CO2. As such it is dependent on large assumptions about natural feedback processes that may not be either true or accurate. Given the size of the natural cycle (20x that of the anthropogenic emissions) there is a lot of room for error. Small changes either natural or man-made in the many natural processes that are much faster than mineralisation would make vast differences to the residency estimate.

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Alan Wilkinson

Water vapour sensitivity

"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."

This simply cannot be correct assuming the equilibrium level increases monotonically with temperature which is what you are assuming when magnifying the CO2 increase.

A small increase in water vapour will generate a small increase in temperature thus supporting a further small increase in water vapour ....

There must be other factors controlling this process. Residence time is not one of them.

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Alan Wilkinson

Re: Another question - clouds

'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."'

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.

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Alan Wilkinson

Ocean chemistry

There are many heroic assumptions in those ocean chemistry models Timothy referenced. Since the current atmospheric:ocean CO2 distribution is apparently 1:50 and the current uptake by natural processes of the anthropogenic CO2 is said to be rather less than 50% there seems a lot of room for slower acting feedback processes to modify the predictions. Only positive feedbacks seem to be incorporated into these models yet normally natural systems are dominated by negative feedbacks?

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Alan Wilkinson

Another simple question

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?

Furthermore, the logarithmic relationship Timothy cites for water vapour if valid would also mean we should be seeing the largest increases in temperature per CO2 increase now and these will continue to diminish substantially and perpetually in the future - subject only to a short mixing lag period. Thus CO2 reduction programmes would become less and less cost-effective as global CO2 levels increase.

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Alan Wilkinson

Water vapour sensitivity

Timothy, there are many points I could take up in your response (incidentally you must be thinking of someone else re the paleorecord) but let's focus on the water vapour question.

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.

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.

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Alan Wilkinson

Popper vs Testability

First, congrats to Timothy Chase for (mostly) sticking to the science and avoiding the pointless mudslinging which seems sadly endemic in this field.

I read his article on Falsifiability vs Testability and was unconvinced. There seem to be several levels on which scientific statements can be made and judged.

Firstly, there is the simple assertion of a direct experimental datum result. Is this reproducible by competent testers? This leads to a true/false judgement within the limits of experimental conditions applied.

Next, there is the hypothesis of a mathematical relationship between measurable properties. Popper's falsifiability test applies (with the proviso again that the testing must be competent and reproducible). However, as in the example of Newton's gravitational laws Timothy gave, utilitarian principles apply. If the hypothesis is more useful over a range of conditions than any other it is not abandoned until it can be replaced by something better. It may be bounded in the meantime or even permanently and come to co-exist with a more complex hypothesis which deals better with the conditions beyond those bounds.

Beyond this are the conceptual model hypotheses such as the atoms and molecules that are the basis of chemistry, the Darwinian evolutionary theory of living organisms or the DNA structural theory of genetics.

These are chosen and survive on the basis of maximum explicative power in the most economical form - "science is only poetry". Here consensus plays a role, though again falsifiability is important and where it occurs it sparks the search for a better model or at the least for a better understanding of the limitations of the model.

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.

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Alan Wilkinson

A simple question

I endorse the criticism that those who indulge in personal attacks rather than focusing on the science simply weaken respect for themselves.

I have a simple question which I haven't seen answered anywhere - which doesn't mean the answer isn't obvious. However:

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 ....

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?

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