NASA says the latest satellite data suggests that one metre or more of sea level rise is unavoidable in the next 100-200 years.
It says ice sheets in Greenland and Antarctica are melting faster than ever, and oceans are warming and expanding much more rapidly than they have in years past.
NASA Earth Science Division director Michael Freilich says rising seas will have profound impacts around the world, which may entirely eliminate some Pacific island nations.
NASA's predictions are based on a series of altimeters that measure ocean height from space.
Dr Freilich says the instruments are so sensitive that if they were mounted on a commercial jet flying at 1,200 metres they could detect the bump caused by a coin lying flat on the ground.