Bishop Hill Conveying truth 4
Apr 3, 2012 Climate: Models As my thoughts have turned increasingly to climate models in recent months, I thought I might take a look to see how Julia Slingo described these mathematical behemoths in the briefing she sent up to central government in the wake of Climategate - I have criticised this document on a number of occasions in the past (1, 2, 3).
Considering just how central climate models are to the case for DAGW* I was taken aback by how little Slingo had to say on the subject. And what she said was, to say the least, surprising. Here it is:
Models have been used that take into account all the factors that influence climate. These models have been able to simulate the historic changes in global and regional temperatures and have shown that most the warming over the past half century has been caused by the rise in greenhouse gas concentrations.
There are a couple of passim mentions elsewhere in the document, but in essence that is what the Met Office feels that people in government need to know about climate models.
It's hard to know where to begin. I wonder whether anyone will seek to defend Slingo's paper as a fair representation of the reliability and importance of climate models.
Readers should feel free to critique Slingo's words, but please avoid venting. I'm more interested in what policymakers should be told about climate models. I think we should allow ourselves slightly more space than Slingo - shall we say eight sentences?
*Dangerous anthropogenic global warming - "dangerous" being perhaps a less emotive term than "catastrophic".
Reader Comments (111)
Apr 3, 2012 at 11:51 PM | Richard Betts
The forcings used to drive the 20th and 21st Century simulations by the AR4 generation of climate models are shown in this table.
H2O seems to be missing in the list of model greenhouse gas forcings - is it dealt with implicitly in the models? If so, on what sort of scale - 1x1x1km for example?
Billy Liar: The IPCC's AR4 excludes atmospheric water vapour [H2O] from all its modelling, on the diktat of Trenberth that as ordinary evaporation precipitates within 8 or 9 days, there is in fact no [H2O] other than that arising from non-solar induced evaporation, viz. GHG-induced warming, and that evaporation NEVER precipitates, producing the positive feedback effect on which the IPCC is reliant for its 3-7oC warming from doubled [CO2]. Next question?
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[Response to O/T}
The basis for the UNEP/IPCC projections is the politically established UNFCCC.
Hos too scientific validate something that is soly based on ideology/politics?
Richard
I don't think your comment on inclusion of the models in Julia's paper is fair. The case for DAGW clearly resides in the models - policymakers need to understand this and they need to understand the limitations of the models. I share your excitement about the spontaneous appearance of ENSO in model simulations, but I also share Brian Hoskins' opinion that the models are "lousy". We may be able to learn something about ENSO from those models that show ENSO behaviour, but this is a different question to whether models are ready to inform policymakers about the future.
This is what Julia should have told Whitehall.
(She also shouldn't have said that global warming is accelerating, right?)
I'm reading the regional hindcast figure with interest. A post may follow.
(She also shouldn't have said that global warming is accelerating, right?)
Anyone who claims to be able to measure even the sign of the second derivative of a noisy signal is (to be polite) out of touch with reality.
Tim Curtin,
Thank you for your reply. I suspected as much. It is hard to believe that the the most visible and potent greenhouse gas in the atmosphere is not represented in models, particularly as it has a unique phase diagram and unique properties.
Perhaps it has been put in the 'too difficult' box.
Billy Liar: thanks for your comment. I see that Richard Betts has yet to respond to my post!
My peer-reviewed paper for the Australian Conference of Economists (ACE2011) dealing with atmospheric H2O, which amply confirms Tyndall's physical experiments (1861), is at that website as well as my own (www.timcurtin.com). Supressio veri (including Tyndall's) is the minimum qualification and stock in trade for ALL climate scientists, including without exception all who contributed to AR4 WG1.
Re: what policymakers should be told about climate models.
How about this:
"The climate models represent poorly thought out junk science designed by scientists who set out to purpose build their results to support their faith, even in the face of contradictory physical evidence. These models are based on unreliable data, do not consider many of the critical climate change factors, incorporate many incorrect applications of the basic science and they offer zero predictive validity with zero reliability. Any politician foolish enough to advance public policy based on these models will be looked upon in a few years time by history with disdain as some sort of cross between Neville Chamberlain and Bernie Madoff. If you want to be judged by history as being either a crook or a giant fool then go ahead and join the climate cult"
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