Review of Spencer’s ‘Great Global Warming Blunder’

Guest commentary from Steve Ghan

A good writer knows their audience, and Roy Spencer knows his. There are plenty of people who would love to hear a compelling argument for why no action is needed to mitigate global warming, and Spencer’s book “The Great Global Warming Blunder: How Mother Nature Fooled the World’s Top Climate Scientists” will give uncritical readers the argument they’ve been looking for. As Sarah Palin said, “while we recognize the occurrence of these natural, cyclical environmental trends, we can’t say with assurance that man’s activities cause weather change”. That is really the essence of Roy’s argument.

What is the Great Blunder? According to his book, “a fundamental mistake has been made in previous interpretations of satellite data”…”a mix-up between cause and effect when analyzing cloud and temperature variations”.

Who made this mistake? Invariably, it is “the IPCC researchers”. He cites a couple of specific papers by Piers Forster, but finds no fault with them. So he casts aspersions into the wind.

Spencer’s assertion in his book of that there has been a “mix-up between cause and effect” is quite a different conclusion from his recent article published in the Journal of Geophysical Research – Atmospheres in 2010, which concluded innocuously that “since the climate system is never in equilibrium, feedbacks in the climate system cannot be diagnosed from differences between equilibrium climate states” … despite the fact that this is the exact diagnosis supporting his conclusion in the book.

In his book Spencer contends that short-term fluctuations in the energy balance and surface temperature are consistent with a low climate sensitivity: “A careful examination of the satellite data suggests that manmade warming due to a doubling of atmospheric carbon dioxide could be less than 1ºC – possibly much less.”

Why does Spencer consider his “discovery” of a mix-up between cause and effect to be so important? Because “natural cloud fluctuations in the climate system will cause a bias in the diagnosed feedback in the direction of positive feedback”, which means those careless IPCC researchers have vastly overestimated the climate sensitivity. He then asserts that “if the real climate system looks sensitive to climate modelers, they will build their models to be sensitive also.” But he never mentions the fact that climate models have produced climate sensitivities of 2-5ºC per doubling of CO2 concentration for decades, well before the Forster papers and before satellite measurements were available for those careless anonymous IPCC researchers to produce biased estimates of climate sensitivity.

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