Comments On A New Paper “A Strong Bout Of Natural Cooling in 2008” By Perlwitz Et Al 2009

There is a new paper

Perlwitz, J., M. Hoerling, J. Eischeid, T. Xu, and A. Kumar (2009), A strong bout of natural cooling in 2008, Geophys. Res. Lett., 36, L23706, doi:10.1029/2009GL041188

with a remarkably convoluted way to rationalize recent cooling in North America so that it conforms with the IPCC perspective of global warming.

The  abstract reads

“A precipitous drop in North American temperature in 2008, commingled with a decade-long fall in global mean temperatures, are generating opinions contrary to the inferences drawn from the science of climate change. We use an extensive suite of model simulations and appraise factors contributing to 2008 temperature conditions over North America. We demonstrate that the anthropogenic impact in 2008 was to warm the region’s temperatures, but that it was overwhelmed by a particularly strong bout of naturally-induced cooling resulting from the continent’s sensitivity to widespread coolness of the tropical and northeastern Pacific sea surface temperatures. The implication is that the pace of North American warming is likely to resume in coming years, and that climate is unlikely embarking upon a prolonged cooling.”

Excerpts from the paper read

Our appraisal of the natural SST conditions in the Nino 4 region, with anomalies of about 1.1 K suggests a condition colder than any in the instrumental record since 1871…..We illustrated that North America would have experienced considerably colder temperatures just due to the impact of such natural ocean variability alone, and that the simultaneous presence of anthropogenic warming reduced the severity of cooling.

“This, and similar recent attribution studies of observed climate events [Stott et al., 2004; Hoerling et al., 2007; Easterling and Wehner, 2009] are important in ensuring that natural variability, when occurring, is not misunderstood to indicate that climate change is either not happening or that it is happening more intensely than the true human influence. In our diagnosis of 2008, the absence of North American warming was shown not to be evidence for an absence of anthropogenic forcing, but only that the impact of the latter was balanced by strong natural cooling. Considering the nature of both the 2008 NA temperature anomalies and the natural ocean variability that reflected a transitory interannual condition, we can expect that the 2008 coolness is unlikely to be part of a prolonged cooling trend in NA temperature in future years.”

This paper is an amazing example of ignoring the obvious. None of the models anticipated this record cooling in the Nino 4 region.  These sea surface temperatures are very much a part of the real climate system, which the IPCC claims can be skillfully predicted decades into the future.

Yet, the model simulations (which themselves are just hypotheses; e.g. see)  are being used to claim that this cooling is just a short-term blip on a long-term upward trend.

The authors, of course, may be correct that the warming will recommence and continue into the future. However, while they did not intend this message, what they have shown convincingly is that natural climate variations exceed what the IPCC models can skillfully simulate. This should give pause to anyone who claims that these models are skillful predictions of the climate in the coming decades.

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