Brace yourself for more hot summers ahead. Extreme weather researchers reported Thursday that climate change makes the searing summer that the struck the United States last year much more likely.
In fact, July 2012-like heat is now four times as likely to strike the Midwest and Northeast as it was in pre-industrial America when less carbon dioxide warmed the atmosphere, according to a Stanford University study. Last year’s heat wave, which peaked in July – the warmest month on record for the contiguous United States – exacerbated the nation’s drought, ruined crops and contributed to more than 100 deaths.
“It was a very rare event. It’s now less rare given current greenhouse gas emissions,” says lead author Noah Diffenbaugh, a climate scientist at Stanford’s Woods Institute for the Environment.
His research is part of a trove of 19 new peer-reviewed studies by scientists worldwide that look at the possible link between climate change and a dozen extreme weather events across the globe last year. About half of the studies say human-caused climate change – due to the burning of fossil fuels and deforestation – contributed to the event examined.
Climate scientists often caution that no single weather event can be blamed on global warming, but Thomas Peterson of NOAA’s National Climactic Data Center says that advances in climate modeling now allow them to “talk” about individual events.
“The models are improving,” agrees Thomas Knutson of NOAA’s Geophysical Fluid Dynamics Laboratory in Princeton, N.J.
Knutson co-authored a study, based on historical data and 23 models, that estimates human-caused climate change contributed 35 percent to the extreme warmth that swept over the eastern United States from March through May last year.
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