Thursday, February 2, 2012

Texas Heat Wave Caused by Global Warming, NASA's Hansen Says by Elizabeth Grossman

Temperature data shows the Texas heat wave wouldn't have occurred without warming, Hansen claims. Others aren't ready to draw such a definitive conclusion.

For three months last summer, temperatures in Texas soared higher than at any time in recorded history, and the state is still coping with the most expensive drought in its history. But can the 2011 Texas heat wave be attributed to global warming?

Most scientists are careful not to link specific weather events to climate change trends, but NASA's James Hansen and two colleagues from the NASA Goddard Institute for Space Studies and Columbia University have taken that plunge. They've gathered data they say shows that the 2011 Texas and Oklahoma heat wave—as well as a deadly Moscow heat in 2010—were "a consequence of global warming because their likelihood was negligible prior to the recent rapid global warming." 

Their conclusions are based on more than 50 years of temperature data, Hansen told InsideClimate News. By comparing the recent shift toward extreme high summer temperatures with that data, he said his group was able to demonstrate that the record-breaking 2011 Texas heat wave wouldn't have occurred without global warming. This data also provides a broader context for the summer of 2011, which across the United States was the second warmest on record, with the National Oceanic and 
Atmospheric Administration's Climate Extremes Index twice the historical average.

Making a connection between the Texas heat wave and climate change could have profound practical and policy implications because, as Hansen and his colleagues write, the global warming trend "has been attributed with a high degree of confidence to human-made greenhouse gases."

Hansen has posted a draft of the new study, Perceptions of Climate Change: The New Climate Dice, on his website and is circulating it to colleagues for comment, a practice he has followed with other research. Meanwhile, NASA's Goddard Institute has posted to the institution's website the scientists' analysis of 2011 temperature data—an analysis that Hansen and his colleagues also used in the new paper.

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