Oceans along the U.S. coastline will rise faster within the next three decades than they did in the past 100 years, bringing more flooding to coastal cities such as New York and Miami, according to the latest projections.

Sea levels are expected to rise as much as 12 inches (30 centimeters) by 2050, according to a U.S. report led by the National Oceanic and Atmospheric Administration (NOAA). While the amounts vary according to region, the inundation will lead to more coastal flooding and make tidal and storm surge more severe, the multi-agency report said.

"Sea levels are continuing to rise at a very alarming rate,” Bill Nelson, administrator of NASA, said Tuesday in a conference call with reporters. "And it’s endangering communities around the world.”