Climate change is not only influencing extreme weather events, it's causing them

Extreme weather events that spanned the globe in 2017 have been directly linked to -- and in some cases were even caused by -- continued warming of the planet via human influence through greenhouse gas emissions, according to a new report.

For the second year in a row, the annual report from the American Meteorological Society found weather extremes that could not have happened without human-caused warming of the climate. Advances in scientific modeling and additional climbs in temperatures are making the connection between global warming and extreme weather much more concrete. 
"Global temperature, the backdrop in which extremes are unfolding, continues to rise. ... Nature is thereby increasingly rolling back its curtain of sensitivity to rising greenhouse gases," Martin Hoerling, a research scientist at the National Oceanic and Atmospheric Administration and one of the authors of Monday's report, wrote in an email. "This alone is making it easier to scientifically identify the fingerprint of human influence, not to mention improved modeling tools," Hoerling said.

Scientists found that record warm waters in the Tasman Sea in 2017 and 2018 "were virtually impossible without global warming," and they concluded that a crippling drought in East Africa that has led to food shortages for millions of people would not have occurred naturally before the Industrial Revolution, when humans began to interfere with the climate system.

Included in the 17 events identified in the report in which global warming played a role were major floods such as those with Hurricane Harvey, fires, heat waves over land and in the ocean, and even record low sunshine in Japan in August 2017.

The findings are part of an annual report titled "Explaining Extreme Events in 2017 from a Climate Perspective," which reveals clear ties between recent extremes in weather and human influences of the climate.

"This is about understanding that climate is already changing the risks of extremes," said Jeff Rosenfeld, editor in chief of the Bulletin of the AMS, the journal in which the report was published.
The report features the research of 120 scientists from 10 countries and examines a wide array of extreme weather and events from 2017. The scientists looked at how these events compare with historical observations as well as model simulations to determine whether there was influence from climate change.

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