Extreme events such as floods and storm surges are likely to increase with a warming climate, threatening low-lying areas in river floodplains and continental coasts. This March 28, 2009 image taken from space shows the swollen Red River snaking through the U.S. cities of Fargo, North Dakota and Moorhead, Minnesota. The river's usual S-shaped curves north and south of Interstate 94 had been swallowed in a bulge of water, and the flooding can be seen encroaching upon the tiny, neat squares that represent neighborhoods. Draining of wetlands and development along river margins contribute to the flooding risk by reducing the area over which water can spread without doing damage. A warming world also makes heavily populated coastal areas more vulnerable to flooding: higher global temperatures produce warmer seawater, which expands and causes a rise in sea level. Approximately 400 million people live within 20 meters (0.01 miles) of sea level and 20 km (12 miles) of a coast; modest increases in sea level could displace millions of people. Image taken by the Advanced Land Imager on NASA's EO-1 satellite on March 28, 2009. NASA image created by Jesse Allen, using EO-1 ALI data provided courtesy of the NASA EO-1 Team.