Living in southern Louisiana without flood insurance is an even bigger gamble after this news from researchers at the National Center for Atmospheric Research: If the climate continues to warm, the big thunderstorms that cause flash flooding probably will become more frequent and more intense, dropping up to 70 percent more rain.

Louisiana’s state climatologist, Barry Keim, agreed with the findings of the study published this month in the journal Nature Climate Change.

“The bottom line is: If you live in moisture-laden places like this, and you increase the temperature even a little bit, you’ll see an increase in thunderstorm activity,” he said.

The report said ocean and air temperatures will continue to rise if greenhouse gases, the driver behind the warming climate, are not reduced. That would increase air moisture in the Southeast, including the Gulf Coast. At the same time, the central part of the country and the Pacific Northwest would see less rain.

Louisiana may be located in Hurricane Alley, but records show the most common cause of flooding here is rain.

Flash floods caused by heavy rains are projected to be responsible for about $8 billion in damage in the New Orleans metro area in the next 50 years, according to researchers for the Urban Water Plan. That’s based on records from the Federal Emergency Management Agency.

Louisiana gets about 6 feet of rain a year, which seldom comes in the form of long, gentle showers. Instead, it often arrives in sudden, brutal thunderstorms spawned by the heat and moisture of the nearby Gulf of Mexico. The storms dump blinding sheets of water that can overwhelm urban drainage systems and cause rural creeks and rivers to jump their banks.

Two such storms struck the southern part of the state this year.

In March, north shore parishes saw catastrophic flooding from intense rainstorms over several days. The state spent more than $10 million for emergency response.

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In August, the Baton Rouge area was hammered for three days with as much as 30 inches of rain, causing 13 deaths and about $8.7 billion in property damage. The federal disaster response cost $660 million.

About 58,000 homes were damaged. Only one in eight was covered by flood insurance, mainly because they were not in federally established flood zones where insurance is required to get a mortgage.

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Ironically, two months later, FEMA issued new flood maps that removed many homes around New Orleans from flood zones. However, state and federal officials recommend everyone buy flood insurance policies even if they're not required to do so.

Scientists saw a direct link between the warming climate and the Baton Rouge storms, pointing to research indicating the risk of such events has increased by 40 percent as the oceans have warmed.

Keim said heat was a major factor in that historic rainfall. Record surface temperatures in the Gulf increased the amount of water vapor rising into the atmosphere, and high air temperatures increased the capacity of the air to hold the water.

However, the factors that caused those storms to stall over the Baton Rouge area for three days are not linked to climate change, Keim said.

The new report, he said, should worry local flood planners because it adds to a growing body of climate science that projects more moisture in the air.

“The conclusions of this paper are not good news for us,” Keim said. “We’re already the wettest state in the lower 48. We don’t need more and more intense storms here.”

To read the original report by The Lens, click here.

Follow Gordon Russell on Twitter, @GordonRussell1.