Changes in ice sheet thickness per year in Greenland (left) and Antarctica (right), shown in dark red, depict a thinning of about 50 cm per year, while purple areas experience a thickening of about 20 cm per year.
After two decades of satellite observations, an international team of experts has produced the most accurate assessment to date of ice losses from Antarctica and Greenland.
The study, a joint effort between the European Space Agency (ESA) and NASA, finds that the combined rate of ice sheet melting is increasing. The 47 experts combined observations from 10 different satellite missions to reconcile the differences among dozens of earlier ice sheet studies and produce the first consistent measurement of polar ice sheet changes.
The new research shows that melting of the Antarctic and Greenland ice sheets has added 11.1 mm to global sea levels since 1992. This amounts to about 20 percent of all sea-level rise over the survey period.
About two-thirds of the ice loss was from Greenland, and the remainder was from Antarctica. Although the ice sheet losses fall within the range reported by the Intergovernmental Panel on Climate Change in 2007, the spread of the estimate at that time was so broad that it wasn't clear whether Antarctica was growing or shrinking.
The new estimates are a vast improvement”more than twice as accurate”thanks to the inclusion of more satellite data, and confirm that both Antarctica and Greenland are losing ice. The study also shows that the combined rate of ice sheet melting has increased over time and, altogether, Greenland and Antarctica are now losing more than three times as much ice, equivalent to 0.95 mm of sea-level rise per year, as they were in the 1990s, equivalent to 0.27 mm of sea-level rise per year.
Images courtesy of Planetary Visions, DTU (Greenland), UCL (Antarctica).
