Climate Change Intensified South Carolina Floods

Scientists say climate change has exacerbated the effects of a storm blamed for at least 12 deaths in the southeastern U.S.

On Monday, after weekend downpours, flooding continued to overwhelm large parts of South Carolina and North Carolina in what was described as a “once-in-a-millennium” storm.

Individual weather events cannot be attributed to climate change, but climatologists say atmospheric conditions tied to climate change intensified this downpour.

“This is yet another example, like Sandy or Irene, of weather on ‘steroids’, another case where climate change worsened the effects of an already extreme meteorological event,” said Michael Mann, director of the Earth System Science Center at Pennsylvania State University.

Mann said hurricane Joaquin intensified in the tropical Atlantic, which is experiencing record sea-surface temperatures.  These temperatures helped the hurricane strengthen quickly and unusually warm, wet air fed it even more.  That moisture turned into the record rainfall which fell on the Carolinas.

“In this case, we’re seeing once-in-a-thousand year flooding along the South Carolina coastline as a consequence of the extreme supply of moisture streaming in from hurricane Joaquin,” Mann said.

The “once-in-a-thousand” phrase does not mean the storm occurs once every 1,000 years, but rather that there is a 0.1% chance of such an intense storm occurring in any year.

After a week of steady rain, thousands of South Carolina residents faced the prospect of going days without running water, and daily life was disrupted by dams overflowing, bridges collapsing and hundreds of roads inundated by floodwaters .

“This is a Hugo-level event,” major general Robert Livingston, head of the South Carolina National Guard, said on Monday, referring to the September 1989 hurricane that devastated Charleston.  “We didn’t see this level of erosion in Hugo. ... This water doesn’t fool around.”
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Dennis Feltgen, a meteorologist and spokesman for the National Oceanic and Atmospheric Administration’s National Hurricane Center, said in an email that “no single weather event can be attributed to climate change."

But government-backed reports show that climate change can exacerbate the severity of storms.  The 2009 National Climate Assessment said that by mid-century some parts of the US could experience two or more days of rainfall per year that exceed local records.

This is happening in parts of South Carolina.  The National Weather Service said that it was the wettest day in the history of Columbia, the state capital.

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