Study: 3.7M in U.S. at flood risk due to warming

(AP) WASHINGTON - Global warming-fueled sea level rise over the next century could flood 3.7 million people in 544 U.S. cities temporarily, according to a new method of looking at risking of rising seas published in two scientific papers.

The cities that have the most people living within three feet of high tide — the projected sea level rise by the year 2100 made by many scientists and computer models — are in Florida, Louisiana, and New York. New York City, often not thought of as a city prone to flooding, has 141,000 people at risk, which is second only to New Orleans' 284,000. The two big Southeast Florida counties, Miami-Dade and Broward, have 312,000 people at risk combined.

"Southeast Florida is definitely the highest density of population that's really on low coastal land that's really most at risk," said lead author Ben Strauss, a scientist at Climate Central. Climate Central is a New Jersey-based group of scientists and journalists who do research about climate change.

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The studies look at people who live in homes within three feet of high tide, whereas old studies looked just at elevation above sea level, according to work published Thursday in the peer-reviewed journal Environmental Research and an accompanying report by Climate Central. That's an important distinction because using high tide is more accurate for flooding impacts, said study co-author Jonathan Overpeck, a scientist at the University of Arizona's Institute of the Environment. And when the new way of looking at risk is factored in, the outlook looks worse, Overpeck said.

"It's shocking to see how large the impacts could be, particularly in southern Florida and Louisiana, but much of the coastal U.S. will share in the serious pain," Overpeck said.

Sea level has already risen about 8 inches since 1880 because of warmer waters expand, Strauss said.

Sea level rise experts at the U.S. Geological Survey and the National Oceanic Atmospheric Administration who weren't part of the studies said the results make sense and were done by experts in the field.

"All low elevation places in the many urban areas along the coast will become more vulnerable, like Boston, New York City, Norfolk (Va.), New Orleans, Charleston (S.C.), Miami, Washington, D.C./Alexandria (Va.)," said S. Jeffress Williams, scientist emeritus for the USGS, who wasn't part of the studies. "More people and infrastructure will be at increasing risk of flooding."