Monday, January 18, 2010

Questions from a fellow blogger

I received the following email regarding some of the results of the survey of climate scienitsts.  Rather than try to answer the questions I thought it more appropriate to post them and let a broader range of opinions to be presented.  Please allow me to introduce myself. I am a British based blogger and lay enthusiastic in most things scientific - but as with most alive at the moment I take particular interest in Climate Science.

I am somewhat late in coming to your Survey of the Perspectives of Climate Scientists Concerning Climate Science and Climate Change but I would like to say that I found the results very interesting indeed.

There is a reassuring pluralism of opinion in the scientific community on climate change, its affects and its modelling. But there was one subset of the survey on which I would like your opinion if possible.

The section which most interested me was on the breadth of opinion on the ability of global and regional climate models to accurately predict specific future events.

However, it seemed that there was a far greater degree of confidence that the world was warming, and that this was anthropogenic in origin, than there was in the models which were used to make those predictions. In my view there are a number of things which account for this difference.

Firstly, there are observational disciplines which complement these models. Next, the reported short comings of some elements of the models - for example, global models predicting extreme events over the next 50 years - little impact the concrete findings in favour of anthropogenic global warming. Also, as the predominance of respondents were involved in physically modelling climate in seems sensible they would spend a large amount of time seeking out flaws in their models in order to improve them.

I was wondering if you had any further insight on this divergence.

Yours Sincerely,

Left Outside.


TCO said...

I think it is very possible to believe in AGW (by that I mean some reasonable agreement with majority style assessments...) WITHOUT thinking the models are useful.

We have some reasonable bases sans model to believe in AGW.

1. The roughly similar runup of temp in the 20th century while CO2 did as well (note...this is a "Bayesian betting inference".) Not some superproof...but enough to alter my BET!

2. Basic radiative physics along with a zero order guess of similar percent humidity, clouds, etc. This is not superproof either...and there may be Lindzenian irises for all I know. But as a BET, I think the iris is rather intricate and wishful and the simplest guess is more that CO2 raises GW (and yes with an amplification from water...that is also to be expecte for a watery "system").


What bugs me about the models is that they are essentially untested/untestable for the types of effects that we want to look at (50 year changes). Also that they are dynamic models for what is something that we essentially want to know in an equilibrium shift manner. Also that the climate itself is an amazingly complicated system and the models are too limited to really capture that without some tweaks (and I think there are enough "handles" in structure and even explicit parameters, not to mention aerosols, etc. to tweak to expected results.) So my "gut" is that they are not really helping us know more. They are right to the extent that they match a sort of common sense Bayesian intuition, but don't really represent a positive, independent corroboration.

P.s. And I think people who have spent lives and livelihoods on doing models have an incentive to keep doing so, to think their work is important, etc. Heck...this is true of any area of science!

Anonymous said...

Climategate Forecast...
“What is the current scientific consensus on the conclusions reached by Drs. Mann, Bradley and Hughes? [Referring to the hockey stick propagated in UN IPCC 2001 by Michael Mann and debunked by McKintyre and McKittrick in 2005.]

Ans: Based on the literature we have reviewed, there is no overarching consensus on MBH98/99. As analyzed in our social network, there is a tightly knit group of individuals who passionately believe in their thesis. However, our perception is that this group has a self-reinforcing feedback mechanism and, moreover, the work has been sufficiently politicized that they can hardly reassess their public positions without losing credibility.”

AD HOC COMMITTEE REPORT ON THE ‘HOCKEY STICK’ GLOBAL CLIMATE RECONSTRUCTION, also known as The Wegman report was authored by Edward J. Wegman, George Mason University, David W. Scott, Rice University, and Yasmin H. Said, The Johns Hopkins University with the contributions of John T. Rigsby, III, Naval Surface Warfare Center, and Denise M. Reeves, MITRE Corporation.