Sea Level Rise: At-Risk Populations

Sea level rise is a global threat. Below, some alarming facts:

• Thirteen of the world’s 20 largest cities are now located on a coast.

• Nearly 25% of the world’s population lives within 62 miles (100 kilometers) of a shoreline, and this figure is likely to increase to 50% over the next 25 years as people flock to coastal cities.

• More than 600 million people live in coastal regions that are less than 10 meters above sea level.

• Two-thirds of the world’s cities have populations of five million or more living in at-risk areas that are less than 10 meter above sea level. (Source

• Thirteen of the world’s fifteen largest cities are on coastal plains. Many smaller cities, such as Alexandria, Egypt’s ancient center of learning, also face a severe risk of inundation with a 39-inch (1m) rise in sea level. 

• Low-lying coastal regions in developing countries such as Bangladesh, Vietnam, India, and China have especially large populations living in at-risk coastal areas such as deltas, where river systems enter the ocean. Both large island nations such as the Philippines and Indonesia and small ones such as Tuvalu and Vanuatu are at severe risk because they do not have enough land at higher elevations to support displaced coastal populations. (Source)

• Some island nations risk the danger of losing their fresh-water supplies as sea level rise pushes saltwater into their aquifers. For these reasons, those living on several small island nations (including the Maldives in the Indian Ocean and the Marshall Islands in the Pacific) could be forced to evacuate over the 21st century. (Source)

• With sea level projected to rise at an accelerated rate for at least several centuries, very large numbers of people in vulnerable locations are going to be forced to relocate. If relocation is delayed or populations do not evacuate during times when the areas are inundated by storm surges, very large numbers of environmental refugees are likely to result. (Source


The U.S. is a coastal nation with more than 12,000 miles of coastline, with more than half of all Americans living in and around coastal cities and towns. And of the top 10 cities/regions threatened by sea level rise, three are in the U.S. (Miami, Greater New York, New Orleans). Cities at risk cover a wide range of economic circumstances, but all require extensive infrastructure development to minimize the potential impacts of flooding, particularly from storm surge. (Source

More about the potential impact to some of of our cities: 


Over the next century, damage in Boston and the surrounding region to residential, commercial, and industrial buildings could exceed $20 billion, depending on how the city responds to rising sea levels. Costs could reach $94 billion, if climate weather conditions are more severe than expected. (Source: Tufts University civil and environmental engineering research professor Paul Kirshen)

Los Angeles

If the Pacific Ocean rises 55 inches by 2100 as scientists predict, Venice Beach could lose up to $440 million in tourism and tax revenue. (Source: Study commissioned by the California Department of Boating and Waterways)

The expected drop in visitors to an eroded Zuma Beach and Broad Beach in Malibu could cost nearly $500 million in revenue. (Source: Study commissioned by the California Department of Boating and Waterways)

New York

If global warming continues, sea levels around New York City could rise by twice as much as other parts of the United States within this century. (source: Nature Geoscience from March 2011) 

San Francisco

The increasingly erosive power of storm surges at San Francisco’s Ocean Beach could cause $540 million in damage to land, buildings, and infrastructure by the end of the century. (Source: Study commissioned by the California Department of Boating and Waterways) 

Coastal California

• Parts of San Jose and Long Beach, California, are roughly three feet below sea level.

New Orleans

• New Orleans is about eight feet below sea level today. 

More on Sea Level Rise

Sea Level Rise: Most Threatened Cities

Sea Level Rise: Facts, By the Numbers

Sea Level Rise: Rapid Ice Shelf Melting