Scientists say between 2000 and 2008, Greenland lost 1500 cubic kilometers of ice, which is responsible for one-sixth of global sea-level rise.
Michiel van den Broeke of Utrecht University in the Netherlands and colleagues say that the bad news is that the rate of ice loss is increasing.
To reach the conclusion, researchers began by modeling the difference in annual snowfall and snowmelt in Greenland between 2003 and 2008 to reveal the net ice loss for each year.
They then compared each year's loss with that calculated from readings by the GRACE satellite, which "weighs" the ice sheet by measuring its gravity.
The researchers found that results from the two methods roughly matched and showed that Greenland is losing enough ice to contribute on average 0.46 millimeters per year to global sea-level rise.
The loss may be accelerating: since 2006, warm summers have caused levels to rise by 0.75 millimeters per year, though van den Broeke says we can't be sure whether this trend will continue.
Sea levels are rising globally by 3 millimeters on average.
The researchers said that half the ice was lost through melting and half through glaciers sliding faster into the oceans.
"The study gives us a really good handle on how to approximate how much ice Greenland is going to lose in the coming century," New Scientist quoted Ted Scambos of the US National Snow and Ice Data Center in Boulder, Colorado, as saying.
The study has been published in the journal Science.