What scientists are learning about the Eemian period could be cause for present-day concern.Based on the study of the paleoclimate record in ice cores as well as the former locations of beaches and coral reefs, researchers believe that the Eemian temperature increase likely pushed global sea levels as high as eight meters (26 feet) above where they are today. That would put many coastal cities deep under water including Miami, the Los Angeles metropolitan area, and large parts of New York [see graphic]. During the Eemian, the polar ice sheets melted over several thousand years; an abrupt increase within the next century—seen by many scientists as inevitable, despite international goals—will not result in a 26-foot rise right away. "Even if you stabilize temperature by 2100, sea levels will keep rising for many centuries after that," says Gavin Schmidt, a NASA climate modeler at the Goddard Institute for Space Studies who specializes in paleoclimate data. The ice sheets will take hundreds of years to fully react to warmer ocean temperatures, he says, "And there won't be very much you can do about it."