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In the News (New York Times):
Cool Spells Are Normal in a Warming World

April 6, 2009

Measured changes in global temperature show ups and downs, with some periods of a decade or more defying the long-term trend. (Graphs provided by the authors, published by the AGU.)
A climate simulation in a world facing “business as usual” increases in greenhouse gases still shows lots of periods with cool fluctuations.

The New York Times reports on a short paper accepted for publication in Geophysical Research Letters which makes a strong case against presenting any argument about human-driven global warming that’s based on short-term trends (a decade or so). The paper is titled simply, “Is the Climate Warming or Cooling?” It is written by David Easterling of the National Climatic Data Center and Michael Wehner of Berkeley Lab’s Computational Research Division. Here is the abstract:

"Numerous websites, blogs and articles in the media have claimed that the climate is no longer warming, and is now cooling. Here we show that periods of no trend or even cooling of the globally averaged surface air temperature are found in the last 34 years of the observed record, and in climate model simulations of the 20th and 21st century forced with increasing greenhouse gases. We show that the climate over the 21st century can and likely will produce periods of a decade or two where the globally averaged surface air temperature shows no trend or even slight cooling in the presence of longer-term warming."

Read the New York Times article.

Read the Geophysical Research Letters paper (subscription required).