Debate about global warming is grubby because there are so many un-acknowledged private agendas running just below the surface. Many participants in the debate have something to gain (if only notoriety) from their advocacy. But attention to the question has provoked a lot of interesting research that tells us something about climate and something about the challenge of making public policy, including multilateral collaboration which is my area of expertise. The only way to erase grubbiness is to pay attention to the data.
Here are some things I’ve been reading lately.
First, on the nature of the “consensus” that Ross Garnaut and many others have cited as the foundation of their faith (it ain’t reason) in IPCC-led alarm: a fascinating set of survey data from Denis Bray and Hans von Storch at the German Institute for Coastal Research. They present the data from their very detailed 2008 mail survey of more than 2600 climate scientists (373 valid responses: 18%). The data shows that most of the respondents believe that climate change presents a very serious threat (mean 5.5/7 s.d. 1.5). But there is a substantial left-side tail; more than a third of the respondents were less certain than that. Bray and von Storch observe that whatever “consensus” means, it is far from ‘unanimity’:
“… rather than a single group proclaiming the IPCC does not represent consensus, there are now two groups, one claiming the IPCC makes overestimations (a group previously labeled skeptics, deniers, etc.) and a relatively new formation of a group (many of whom have participated in the IPCC process) proclaiming that IPCC tends to underestimate some climate related phenomena.”
A second conclusion emerges from looking at the data from another angle:
“… to examine the terminology concerning two key concepts in climate science, namely “predictions” and “projections”, as used among climate scientists. The survey data suggests that the IPCC terminology is not adopted, or only loosely adopted, by a significant minority of scientists. Approximately 29% of the sample associate probable developments with projections and approximately 20% of respondents associate possible developments with predictions.”
One of the most interesting aspects of the Bray and Storch survey data is the lack of confidence in current climate models’ simulation of key climate parameters such as rainfall, clouds and albedo (belying the respondents’ overall confidence in the IPCC risk assessment)..
There is more detail on this question in a second paper I’ve read lately. Peter Müller of the Department of Oceanography at the University of Honolulu has contributed a very accessible review article to the Wiley Interdisciplinary Review journal on Climate Change entitled “Constructing climate knowledge with computer models” that is freely available. He makes a dozen points about the nature of the uncertainties incorporated in the current general circulation models (especially about the mathematical challenges of estimating parameters for, and solving, the chaotic Navier-Stokes fluid dynamics equations); about the frailty of the models’ continent-wide resolution; about the use of the current models as scenarios rather than forecasts; about their (lack of) calibration to current conditions, about the human factors and political contexts of any modelling etc.
Müller’s review is well worth reading for its expert overview and accessibility. Another excellent guide is contained in this recent article by Judith Curry (the Chair of the School of Earth Sciences at the Georgia Institute of Technology)
The third paper I’ve read recently is an “oldie but a goodie”. Richard Lindzen’s 1990 (!) paper: Some Coolness Regarding Global Warming is an accessible, short explanation of the nature of radiative balance and the “greenhouse effect” (which is nothing like a greenhouse) from a well-qualified academic who — as the paper demonstrates — has been sceptical of the alarmist thesis on physical grounds for two decades or more.