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Studies Document Increased Flooding from Climate Change


Lynda Mettee lives in a house built high up on risers on a slender peninsula called Swan Point that sticks out into the Chesapeake Bay east of Dundalk, in Baltimore County.

She does not need scientists to tell her that floods are becoming more common. A neighbor in a kayak told her as he paddled right down the middle of her street on April 30.  She illustrates this by showing  dramatic flood photos on her iPhone.

“These are pictures where the water was so high that it covered the entire road and you couldn’t even see where the edges of the road were,” said Mettee, a 45-year-old physician’s assistant who lives on Cuckold Point Road. “Even in the past five to seven years we’ve noticed the coastal floods have been increasing. Where it used to happen once or twice a year, this year it’s happened three or four times.”

A new study by the National Oceanic and Atmospheric Administration concludes that flooding – driven by climate change and rising sea levels and higher tides – is accelerating at 75 percent of locations on the East and Gulf coasts. Last year, 19 areas broke or tied previous records for flooding, including six in Maryland and Virginia, according to NOAA oceanographer William Sweet.  

“Every year, high tide flooding seems to be breaking records,” said Sweet. “Annapolis had 18 days last year. That’s an all-time record. Baltimore had 11 days.  That was just one day off its record that was set the year before.  Twenty years ago, these locations would have experienced two to three days of this flooding.  But now, just a change in prevailing winds can raise the bay and pass the brim and flood into our streets.”

Research by the nonprofit First Street Foundation found that the flood risk for millions of homes and businesses across the U.S. is actually much higher than government estimates. This is because outdated flood plain maps drawn by the Federal Emergency Management Agency do not account for the increasing intensity and volume rainfall already falling because of climate change.

FEMA maps often hide or downplay real flood risk in part because of political pressure from real estate developers or owners who want to make money from flood-prone properties, or avoid paying higher flood insurance rates.

Jeremy Porter is Director of Research at the First Street Foundation, which investigated the problem.

“Across the country, we found about 1.7 times – or 70 percent more – properties have flood risk in a one in one hundred year flood event than what the FEMA special flood hazard areas show,” Porter said. “FEMA finds about 8.7 million properties at risk, and we find about 14.6 million properties at risk.”

In the Baltimore County community of Swan Point, for example, the First Street Foundation’s online database – called FLOOD FACTOR -- shows that nearly every single home – including Lynda Metee’s-- faces an extreme flood risk, with a more than a 99 percent chance of flooding. Many of these waterfront houses are already up on stilts or extra-high foundations, having been built or rebuilt after the community was devastated by Tropical Storm Isabel.

Another major flooding risk area in Maryland, according to the FLOOD FACTOR database, is Ocean City, where 85 percent of the 7,400 homes and businesses are already at risk of flooding. This is expected to rise to 96 percent within 30 years as climate change continues.

One solution would be to build more seawalls. But no rocks can stand long against the rising oceans.  Mike Tidwell, director of the Chesapeake Climate Action Network, said the only long-term answer is to stop burning the fossil fuels that are the root cause of the flooding.

“It’s ironic that the mayor of Ocean City – and some of the members of the tourism boards there – have been opposed to offshore wind farms,” said Tidwell. “But it’s the only way we’re going to keep the ocean out of Ocean City is by transitioning to clean energy.”


Photo of flooding in downtown Annapolis from the Chesapeake Bay Program

Tom Pelton, a national award-winning environmental journalist, has hosted "The Environment in Focus" since 2007. He also works as director of communications for the Environmental Integrity Project, a non-profit organization dedicated to holding polluters and governments accountable to protect public health. From 1997 until 2008, he was a journalist for The Baltimore Sun, where he was twice named one of the best environmental reporters in America by the Society of Environmental Journalists.