A rising tide lifts all boats, but it can also flood coastal real estate. Several studies suggest that global sea level will rise at least 1 meter by 2100. Using high-resolution topographical data collected by the U.S. Geological Survey, researchers have now found that almost 32,000 square kilometers of land—an area almost the size of Maryland—lie within 1 meter of the highest level now reached by high tides along coasts in the lower 48 states. Census data show that about 3.7 million people, or about 1.2% of the nation's population, live in that swath and that 89% of at-risk residents live along the shores in just five states: Florida, Louisiana, California, New York, and New Jersey. In 544 municipalities and in 38 counties, more than 10% of the population resides within 1 meter of the current high-tide line, the researchers report online today in Environmental Research Letters. Altogether, they say, portions of some 2150 cities and towns will be inundated at high tide when sea level rises 1 meter. That includes areas in and around New York City, New Orleans, the San Francisco Bay Area, and greater Los Angeles. Besides threatening regular inundation at high tides, rising sea levels will make storm surge driven by hurricanes and strong tropical storms higher and more frequent.
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