Climate Change to Bring Dramatic Surge in East Coast Floods, Scientists Warn

Dozens of cities and towns on the U.S. Atlantic coast will face a dramatic increase in tidal flooding within just 15 years as a direct result of climate change-driven sea level rise, with some communities projected to face such frequent flooding in the near future they could become unlivable, a study released Wednesday reveals.

The report, entitled Encroaching Tides: How Sea Level Rise and Tidal Flooding Threaten U.S. East and Gulf Coast Communities over the Next 30 Years, was published by the Union of Concerned Scientists. Researchers analyzed National Oceanic and Atmospheric Administration tide gauges for 52 cities from Maine to Texas and then used this data to project future sea rise and metropolitan flooding.

The report finds that most cities and towns on the Atlantic coast already face dozens of high tide floods on an annual basis as a result of climbing sea levels, which rose about 8 inches between 1880 and 2009. In just 15 years, this problem is projected to grow worse. By 2030, over half of the 52 cities analyzed will face an average of two dozen of such floods a year. And two-thirds of the 52 cities evaluated will see three times the amount of floods they face today.

For some cities, this boosts flood frequency to staggering levels. Annapolis, Maryland and Washington, D.C. are two cities that, in 15 years, will face over 150 tidal flood events annually.

In 30 years, many coastal cities will experience a sea level rise of one foot, the study finds. This translates into a drastic increase in flooding compared to historic rates. One third of the cities evaluated will face tidal flooding over 180 times a year on average, with nine cities facing an average of 240 floods per year. These trends will hit Mid-Atlantic towns and cities especially hard. In 2045, Annapolis, Maryland; Lewisetta, Virgina; Washington, D.C.; and Wilmington, North Carolina could face more than 300 floods annually.

Furthermore, rising sea levels will mean that, in just 15 years, these floods will last longer, reach further inland, and cause more damage and disruption.

"Around the world, sea level is rising in response to global warming. As the oceans heat up, the water expands and as glaciers and polar ice sheets melt they add water to the oceans," said Melanie Fitzpatrick, UCS climate scientist. "Only international and national actions to deeply and swiftly reduce global warming pollution can slow the pace of future sea level rise."

The report urges municipal, state, and federal governments to take immediate steps to prepare coastal communities from increased floods by upgrading infrastructure, such as sea walls, and developing long term plans for the increased flood, and ultimately, to create a plan to curb the greenhouse emissions driving global warming. However, the report notes that human capacity to adapt to the rising sea levels has its limits: "As sea level rises, even our best protection efforts will not suffice in some areas in the face of rising tides, waves, and storm surges."