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 ones 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.”
Note added in proof: We have assessed the CRU data independently and show that in terms of long term trends it is no different than the underlying raw data. So the instrumental temperature data aren’t going to change, and neither is the climate sensitivity (to the extent it depends on those data), so neither are projections of the future.
Wigley et al., The observed global warming record: What does it tell us? Proceedings of the National Academy of Sciences 94, 8314–8320 (1997).
Knutti R. & G.C. Hegerl. The equilibrium sensitivity of the Earth’s temperature to radiation changes. Nature Geoscience 1, 735 – 743 (2008).
*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.