The deniers have been trumpeting an atrocious study that made it into the July 23 edition of Journal of Geophysical Research, “Influence of the Southern Oscillation on tropospheric temperature.” The top anti-scientific blog, WattsUpWithThat, crowed, “Surge in global temperatures since 1977 can be attributed to a 1976 climate shift in the Pacific Ocean”:
A new peer-reviewed climate study is presenting a head on challenge to man-made global warming claims.
But let’s not waste time quoting that “atrocious paper,” as RealClimate puts it, with a couple of debunking links here. The occasional atrocious denier paper sometimes makes it through the peer-reviewed process. What’s truly remarkable here is that some of the top climate scientists in the country already have a response submitted for publication in JGR — see full article here.
Last year saw “A new Olympic record for retraction of a denier talking point,” but this would seem to be some sort of a world record for scientific rebuttal.
The nine (!) rebuttal authors span the globe from Japan to the UK to New Zealand to Colorado and New York, reading like a who’s who of global climate science: G. Foster, J. D. Annan, P. D. Jones, M. E. Mann, B. Mullan, J. Renwick, J. Salinger, G. A. Schmidt, and K. E. Trenberth. Here’s the abstract:
McLean et al. [2009] (henceforth MFC09) claim that the El Niño/Southern Oscillation (ENSO), as represented by the Southern Oscillation Index (SOI), accounts for as much as 72% of the global tropospheric temperature anomaly (GTTA) and an even higher 81% of this anomaly in the tropics. They conclude that the SOI is a “dominant and consistent influence on mean global temperatures,” “and perhaps recent trends in global temperatures”. However, their analysis is incorrect in a number of ways, and greatly overstates the influence of ENSO on the climate system. This comment first briefly reviews what is understood about the influence of ENSO on global temperatures, then goes on to show that the analysis of MFC09 severely overestimates the correlation between temperature anomalies and the SOI by inflating the power in the 2-6 year time window while filtering out variability on longer and shorter time scales. It is only because of this faulty analysis that they are able to claim such extremely high correlations. The suggestion in their conclusions that ENSO may be a major contributor to recent trends in global temperature is not supported by their analysis or any physical theory presented in that paper, especially as the analysis method itself eliminates the influence of trends on the purported correlations.
Ouch! One wonders how MFC09 made it through peer review in the first place. JGR really, really screwed up. Here is the conclusion of Foster et al.:
It has been well known for many years that ENSO is associated with significant variability in global mean temperatures on interannual timescales. However, this relationship (which, contrary to the claim of MFC09, is simulated by global climate models, e.g. Santer et al. [2001]) cannot explain temperature trends on decadal and longer time scales. The analysis of MFC09 grossly overstates the influence of ENSO, primarily by filtering out any signal on decadal and longer time scales. Their method of analysis is a priori incapable of addressing the question of causes of long-term climate change. In fact, the general rise in temperatures over the 2nd half of the 20th century is very likely predominantly due to anthropogenic emissions of greenhouse gases [IPCC, 2007].
Doh. Or is that Duh?
Either way, this won’t silence the deniers — since they are not persuadable by evidence (see “Can you PROVE to me that global warming is being caused by mankind?”*). But everyone else can rest assured that the scientific process works itself out, 99 peer-reviewed papers out of 100 make clear humans are already changing the climate, and, tragically, the threat to the health and well-being of the next 50 generations posed by human-generated emissions of GHGs remains unabated.
Very big hat tip to Andy Revkin (his twitter comments are here) for sending me the link to Foster et al.
