Monday, May 08, 2017

Extreme Weather Flooding the Midwest Looks a Lot Like Climate Change

I notice that most of the areas in this weather event voted for Trump, who has denied climate disruption, and has taken steps to block action on global warming, and removed information on it from government web pages.

By Phil McKenna
May 6, 2017

Devastating storms still roiling much of the American Midwest have dumped record levels of rain over the past week and caused flash flooding that has killed at least 10 people, inundated towns and highways, and forced hundreds of people to evacuate their homes. Parts of Missouri, Illinois, Indiana, Arkansas and Louisiana received 10 to 15 inches of rain in the past seven days, according to the National Weather Service, resulting in record crests of numerous rivers across the central United States.

Extreme storms like these have become more common as global temperatures have risen and the oceans have warmed. Some have the clear fingerprints of man-made climate change.

"Of course there is a climate change connection, because the oceans and sea surface temperatures are higher now because of climate change, and in general that adds 5 to 10 percent to the precipitation," Kevin Trenberth, a climate scientist with the National Center for Atmospheric Research, said. "There have been many so-called 500-year floods along the Mississippi about every five to 10 years since 1993."


"Across the board, the United States has seen an increase in the heaviest rainfall events, and the Midwest specifically has seen an increase [in these events] of almost 40 percent," said Heidi Cullen, chief scientist at Climate Central and a member of World Weather Attribution (WWA), a group that is developing methods to quickly determine climate change's role in extreme weather events.

Like last summer's downpours in Louisiana, however, the ongoing storms across much of the central U.S. are moving slowly, a characteristic that has not been directly attributed to climate change and has likely exacerbated current flooding.


Climate scientists explain that as the planet warms, evaporation increases, leading to more moisture in the atmosphere and more precipitation. Across the Midwest, upper Great Plains and Northeast, the amount of precipitation during very heavy events has increased more than 30 percent above the 1901-1960 average, according to the third National Climate Assessment.

Flooding, too, has risen in several of these regions. Storms characterized as 500-year events, meaning they have an amount of precipitation expected to occur once every 500 years, have increased. The Louisiana storms last summer had been the eighth 500-year event in the U.S. in just over a year.


"We expect to see more extreme heavy rainfall events like this in the future, and, as a result, we very much need to be having a conversation about our infrastructure," Cullen said. "Hospitals, schools, military bases will flood during these extremes. We need to do a very careful analysis of how we are going to respond to the fact that the risk is increasing."

tags: extreme weather

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