(MCT) — WASHINGTON — The loss of ice covering Greenland and Antarctica has accelerated over the past 20 years, contributing substantially to sea level rise, according to a study conducted by 26 laboratories around the world.

The study, supported by NASA and the European Space Administration and published Thursday by the journal Science, estimates that about 20 percent of current sea-level rise can be attributed to the 344 billion tons of glacial ice lost annually in Greenland and Antarctica.  (The other major factors behind sea level rise are expansion of the oceans as they warm and melting of mountain glaciers, whose waters eventually run into the sea.)