NASA mapping 16 years of Greenland and Antarctica ice sheet loss
NASA uses some of the most sophisticated laser technology in their space missions. In 2018, they launched 'Ice, Cloud and land Elevation Satellite 2' (ICESat-2) to measure the thickness of the ice sheets in Greenland and the Antarctic. This satellite uses a special laser altimeter. This instrument sends 10,000 pulses of light a second down to Earth’s surface and measures the time how long it takes to return.
Through this mission the new data gained in 2019 could be compared with an earlier mission which had begun in 2003 and map the results. The new insights show how polar ice sheets are changing over time.
The study further explains that due to global warming some parts of Antarctica received more snowfall which increased ice gains while other parts, especially in West Antarctica, experienced a massive loss of ice sheet.
“If you watch a glacier or ice sheet for a month, or a year, you’re not going to learn much about what the climate is doing to it,” said Ben Smith, a glaciologist at the University of Washington. “We now have a 16-year span (...) and can be much more confident that the changes we’re seeing in the ice have to do with the long-term changes in the climate.”
In Greenland coastal glaciers get thinned out due to warmer ocean water. Warmer water and warmer temperatures erode the ice of the glaciers' ice sheets and ice shelves.
Sea levels rise due to the loss of ice sheets, while the thinning of ice shelves, which are floating masses of ice carrying the ice sheets, do not lead per se to sea level rise. However, the thinning of the ice shelves decreases stability of the glaciers and ice sheets. Some glaciers in Greenland have lost up to 6 metres/ 20 ft of elevation per year!
In total, Greenland’s ice sheet was found to have lost an average of 200 gigatons of ice per year. Antarctica lost in these 16 years an average of 118 gigatons of ice per year.
How much is one gigaton? One gigaton of ice would be enough material to fill 400 000 Olympic-sized swimming pools or cover Central Park in New York in ice more than 300 metres/ 1000 ft thick! This would in fact be higher than the Chrysler Building which has a hight of 282 m/ 925 ft.