Who you gonna call?
The problem of ‘false balance’ in reporting — the distortions that can result from trying give equal time to the two perceived sides of an issue — is well known. In an excellent editorial a few years ago, the Seattle Post-Intelligencer called for a greater emphasis on truth, rather than ‘balance.’ Unfortunately, this basic element of careful journalism seems to have been cast aside, especially in recent weeks.
I was both amused and stunned by the effort at ‘balance’ provided by Richard Harris’s report on NPR, in which he claimed that the peer review process was “so distorted” that neither John Christy nor Jim Hansen can get their work published. Notwithstanding the simple fact that both of these scientists publish regularly in leading journals, Harris’s attempt to present ‘both sides’ of the issue completely undermines his thesis. Christy thinks that the IPCC overstates the consequences of climate change, while Hansen thinks it understates it. If both feel the peer review process is biased against them, then it must be working rather well. This doesn’t mean they are wrong, but science is a conservative enterprise, and it is evident that neither of them has provided sufficient evidence for extraordinary claims.
More bizarre is that some journalists seem to have decided that scientists no longer have credibility and hence one can now turn to whomever one wants for expert advice. A case in point is Andrew Revkin’s recent query to political scientist Roger Pielke, Jr. Revkin asked, “If the shape of the 20th-century temperature curve were to shift much,” would that “erode confidence that most warming since 1950 is driven by human activities?” Pielke replied that “the surface temps matter because they are a key basis for estimates of climate sensitivity,” and that there will ultimately be a “larger error bars around observed temperature trends which will carry through into the projections.”
We appreciate that Revkin may be trying to use voices that will appear ‘centrist’ to most of his audience. But Pielke’s answers, while they sound very reasonable, are wrong.
Obviously, radical changes to the long term trend in the surface temperature record would require re-evaluation of our understanding of climate sensitivity, but such radical changes are almost impossible to envision happening. This is so because: (1) independent assessments of the surface temperature data (such as by the Japanese Meteorological Agency) agree extremely well with one another, and (2) independent evidence from borehole temperatures fully validate the long term surface trend (and actually suggest it is larger than, for example, indicated by proxy temperature constructions).
The only conceivable changes to the record of surface temperatures are in the short term variability, which provide very little constraint on the climate sensitivity (see, e.g., Wigley et al. (1997) and Knutti and Hegerl’s 2008 review of research on climate sensitivity). And perhaps most importantly, the instrumental temperature data can especially not be used to exclude high values of climate sensitivity, because any small errors that may exist in those data are completely overwhelmed by the uncertainties in aerosol radiative forcing and ocean heat uptake. In short, in the unlikely event of any changes to the surface temperature record, the changes will be too small to have any impact on projections of the future.* (See also our earlier post on climate sensitivity, Plus ça change….)
All of which goes to show that, even if one thinks it inappropriate for scientists to talk about politics, it still might be useful to ask them about technical issues.
There’s no need to rely on RealClimate: there are hundreds of other experts that can be asked. As a colleague recently wrote independently to Revkin, “You have a very good Rolodex. If you want to ask somebody a technical question about climate science … please use it.”
——
References
Knutti R. & G.C. Hegerl. (2008). The equilibrium sensitivity of the Earth’s temperature to radiation changes. Nature Geoscience 1, 735 – 743.
Wigley et al. (1997). The observed global warming record: What does it tell us? Proceedings of the National Academy of Sciences 94, 8314–8320.
*Edited from earlier version for clarity; the original read, “In short, in the unlikely event of any changes to the surface temperature record, it will have no impact on projections of the future.” This may have confused some readers to think that I was saying it would be impossible in principlefor any change — no matter how large — to have any impact. This is obviously not the case.
Link: http://www.realclimate.org/index.php/archives/2009/12/who-you-gonna-call/
Comments by Pielke fils and responses:
36
Roger Pielke, Jr. says:
5 December 2009 at 4:51 PM
Hi Eric-
Again, Revkin did not ask me if it was plausible that the temperature record would shift much, he simply assumed it in the question and I assumed it in the answer. It would be a little like me asking you, assume a major volcanic eruption occurred in 2010, what would be the climate consequences?
One response might be: “hmmm that is an interesting thought experiment. What might the answer be?”
Another might be “Eric is not a vulcanologist, why ask him this? Besides the chances of a big volcanic eruption are really small.”
Your post is quite a bit like the second response.
Again, I said nothing more than you said yourself: “radical changes to the long term trend in the surface temperature record would require re-evaluation of our understanding of climate sensitivity”.
Are radical changes possible? Don’t ask me, I’m a political scientist;-) But in any case you should be heartened by my answers, which explained that even if this occurred, it does not much change the science or policy equation — from the perspective of the social construction of science — which I take it is just about where you come out asking a different question about plausibility. So it appears we are in violent agreement from very different perspectives.
[Response: The right response to your hypothetical would be, "First, let me be very clear that a major eruption in any given year is very unlikely...." and then to answer the question.
Furthermore, to repeat this once more, as clearly as I can: *What you said* was mostly wrong, *even* in response to a hypothetical "really big change." What you said about how climate sensitivity is estimated was wrong, and what you said about how estimates of climate sensivity wind up in projections of the future was wrong. And overall, what you said was grossly misleading because it strongly implies (since you did not bother to give the caveat at the beginning, analogous to the caveat about the volcano) that big changes to our estimates of climate sensitivity might well come from an actual fresh and independent look at the surface temperature records. While *technically* accurate (anything is *possible*), that is a very misleading statement. And it is very very misleading to suggest that that would translate directly into changed projections. And that supports the view that questions raised by the CRU emails cast doubt on future projections, which is very very very misleading. One more 'very' and I think it simply becomes 'dishonest'.
But, that's all water under the bridge I suppose because you now say you agree with me that if Revkin had asked a better question, such as "Is it at all likely that any of this matters to future projections?" you would have answered "No, it is not at all likely." Right?--eric]
Posts
No comments:
Post a Comment