This all follows on from Naomi Oreskes' investigation into the existence of a consensus in the literature basically on the question as to whether the future holds an unusual amount of climate disruption. (It does and the literature is consistent with near unanimity on that question.)
But whether there is, as is commonly claimed a "97%" consensus depends crucially on who you include as a scientist, what question you are asking, and how you go about asking it.
I think the most consistent and interesting pattern is that the more a person specializes in climate as a physical system, the more alarmed they are by our future prospects. At least two surveys have shown this.
Doran & Zimmerman 2009
1. When compared with pre-1800s levels, do you think that mean global temperatures have generally risen, fallen, or remained relatively constant? 2. Do you think human activity is a significant contributing factor in changing mean global temperatures?
In general, as the level of active research and specialization in climate science increases, so does agreement with the two primary questions (Figure 1). In our survey, the most specialized and knowledgeable respondents (with regard to climate change) are those who listed climate science as their area of expertise and who also have published more than 50% of their recent peer-reviewed papers on the subject of climate change (79 individuals in total). Of these specialists, 96.2% (76 of 79) answered “risen” to question 1 and 97.4% (75 of 77) answered yes to question 2.
This result is further confirmed by a more recent and more extensive study conducted by Verheggen et al. There's much of interest there, but I'd like to focus on the following, which examines the distribution of opinion among the group that the prior study would consider the most expert.
When science discovers something alarming, how does the alarm propagate? It makes sense that the best informed people would be the most alarmed if the cause for alarm is real, while if it is dubious or baseless, the distribution would be very different.
But why examine the consensus itself? Why have there been these various follow-ons to Oreskes' study? It seems to be largely driven by a group of naysayers who wish to insist either that there is no such consensus at all, or that consensus is an illegitimate basis for argument.
This should all come as something of a shock to people interested in public health, where a formal consensus process has long been the mechanism of interaction between science and policy. For instance, "In the United States, for example, the National Institutes of Health promotes about five to six consensus panels per year, and organizes this knowledge by means of a special Consensus Development Program, managed by the NIH's Office of Disease Prevention (ODP)."
So why doesn't climate science have such a consensus process? That should settle all this argument and allow us to move on on the basis of formally selected information. It seems like a good idea. Indeed, right-wing commentator Peggy Noonan suggested exactly this in 2006:
During the past week's heat wave--it hit 100 degrees in New York City Monday--I got thinking, again, of how sad and frustrating it is that the world's greatest scientists cannot gather, discuss the question of global warming, pore over all the data from every angle, study meteorological patterns and temperature histories, and come to a believable conclusion on these questions: Is global warming real or not? If it is real, is it necessarily dangerous? What exactly are the dangers? Is global warming as dangerous as, say, global cooling would be? Are we better off with an Earth that is getting hotter or, what with the modern realities of heating homes and offices, and the world energy crisis, and the need to conserve, does global heating have, in fact, some potential side benefits, and can those benefits be broadened and deepened?
Also, if global warning is real, what must--must--the inhabitants of the Earth do to meet its challenges? And then what should they do to meet them? You would think the world's greatest scientists could do this, in good faith and with complete honesty and a rigorous desire to discover the truth.You know what would be a great pity, though? What if there had been a consensus process of just this sort in place for decades, and nobody noticed. Fortunately the world is not that silly, is it?