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Natural variability led to extra-cold 2008, research finds

Date:
December 31, 2009
Source:
American Geophysical Union
Summary:
An especially cold year in North America in 2008 led some members of the public and the media to question the scientific consensus on human-induced global warming. In addition, the cool global temperatures during the past decade may appear to contrast with the warming expected due to human influence. New research finds that the anthropogenic forcing in 2008 did contribute to temperatures warmer than would otherwise have occurred but that those human-induced effects were overwhelmed by a particularly strong bout of natural cooling.
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New research finds that anthropogenic forcing in 2008 did contribute to temperatures warmer than would otherwise have occurred but that those human-induced effects were overwhelmed by a particularly strong bout of natural cooling.
Credit: iStockphoto/Todd Lammers

An especially cold year in North America in 2008 led some members of the public and the media to question the scientific consensus on human-induced global warming. In addition, the cool global temperatures during the past decade may appear to contrast with the warming expected due to human influence.

To clarify the roles of human influence and natural climate variability, Perlwitz et al. used observed temperature data and a suite of climate model simulations to analyze factors contributing to the 2008 North American temperature conditions.

The researchers found that the anthropogenic forcing in 2008 did contribute to temperatures warmer than would otherwise have occurred but that those human-induced effects were overwhelmed by a particularly strong bout of natural cooling. The authors determined that the North American cooling likely resulted from a widespread natural coolness in the tropical and northeastern Pacific Ocean.

The study implies that the abnormally cool 2008 is not likely part of a prolonged cooling trend and that general warming trends are likely to continue.

The research is published in Geophysical Research Letters. Authors include Judith Perlwitz, Jon Eischeid, and Taiyi Xu: Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA, and Earth System Research Laboratory, NOAA, Boulder, Colorado, USA; Martin Hoerling: Earth System Research Laboratory, NOAA, Boulder, Colorado, USA; and Arun Kumar: Climate Prediction Center, NOAA, Camp Springs, Maryland, USA


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The above post is reprinted from materials provided by American Geophysical Union. Note: Materials may be edited for content and length.


Journal Reference:

  1. Perlwitz et al. A strong bout of natural cooling in 2008. Geophysical Research Letters, 2009; 36 (23): L23706 DOI: 10.1029/2009GL041188

Cite This Page:

American Geophysical Union. "Natural variability led to extra-cold 2008, research finds." ScienceDaily. ScienceDaily, 31 December 2009. <www.sciencedaily.com/releases/2009/12/091230183204.htm>.
American Geophysical Union. (2009, December 31). Natural variability led to extra-cold 2008, research finds. ScienceDaily. Retrieved September 5, 2015 from www.sciencedaily.com/releases/2009/12/091230183204.htm
American Geophysical Union. "Natural variability led to extra-cold 2008, research finds." ScienceDaily. www.sciencedaily.com/releases/2009/12/091230183204.htm (accessed September 5, 2015).

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