Climate change has a human cost.

To illustrate that cost, Rep. Henry Waxman (D-Calif.), ranking member of the Energy and Commerce Committee, recently invited citizens affected by climate and extreme weather events to speak before members of the U.S. House of Representatives. Stanford Woods Institute Senior Fellow Noah Diffenbaugh (Earth Sciences) was the only climate expert invited to provide a scientific perspective.

The meeting of the Safe Climate Caucus, an informal group Waxman heads, came a day before the House energy panel was set to question Cabinet members about the President’s Climate Action Plan and a few days before the U.S. Environmental Protection Agency was set to release carbon dioxide rules for new power plants.

“Global warming has already increased the risk of at least some of the most high-impact extreme weather events,” Diffenbaugh said in his testimony. “In addition, a large body of evidence suggests that the risk of these kinds of extremes is likely to further increase if global warming continues in the future.”

Woods Fellow Noah Diffenbaugh speaks at congressional meeting on climate change (beginning at 0:47:18)

Diffenbaugh joined a New York resident who described living through Superstorm Sandy in 2012, a California resident whose community is suffering the effects of a massive wildfire, a Louisiana resident helping his community rebuild after hurricanes Katrina and Rita, and a Texas bison rancher and Iowa farmer who worried about climate change-driven precipitation changes that threaten water sources and crop irrigation.

A recent study by Diffenbaugh and Martin Scherer, a research assistant in the Stanford Environmental Earth System Science Department, found that in the north-central and northeastern United States, extreme weather is more than four times as likely to occur than it was in the pre-industrial era. Diffenbaugh and Scherer found strong evidence that the high levels of greenhouse gases now in the atmosphere have increased the likelihood of severe heat such as occurred in the United States in 2012. (Read more about the study.)

This past spring, Waxman’s office contacted the Stanford Woods Institute for climate change expertise. Diffenbaugh was among the Woods researchers who responded to Waxman’s questions.

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