NASA documents terrifying ice loss in Greenland, Antarctica
Ocean warming is causing massive ice sheet loss in Greenland and Antarctica, NASA study shows
CNN.com, May 1, 2020
A new study by NASA shows that Antarctica and Greenland's ice sheets lost 118 gigatons and 200 gigatons of ice on average per year. That would fill more than 127 million Olympic-sized swimming pools.
According to NASA, the amount of ice lost could cover New York's Central Park in ice more than 1,000 feet thick, reaching higher than the Chrysler Building.
This loss of ice has caused the sea level to rise by about half an inch between 2003 and 2019. That's slightly less than a third of the total amount of sea level rise observed in the world's oceans, according to the study.
And although East Antarctica has gained some ice, that gain is little compared to the total amount of ice lost in the other areas.
Warmer summer temperatures are chiefly to blame for this ice loss, according to NASA. The warm temperatures have melted ice from the surface of the glaciers and ice sheets.
NASA says it recorded the data from its Ice, Cloud and land Elevation Satellite 2 (ICESat-2), which was launched in 2018 to make detailed global elevation measurements, including over the Earth's frozen regions. That data was then compared with measurements taken by the original ICESat from 2003 to 2009, allowing researchers to generate a complete picture of the complexities of ice sheet change and insights into the future of Greenland and Antarctica.
"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 and lead author of the new paper.
He told NASA, "We now have a 16-year span between ICESat and ICESat-2 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."
Using the most advanced Earth-observing laser instrument NASA has ever flown in space, scientists have made detailed measurements of how the elevation of the ice sheets in Greenland and Antarctic have changed over 16 years.
Alex Gardner, a glaciologist at NASA's Jet Propulsion Laboratory in Southern California and co-author of the Science paper, told NASA that the new analysis reveals the ice sheets' response to changes in climate in great detail, revealing clues as to why and how the ice sheets are reacting the way they are.
The NASA study also looked at ice shelves: the floating masses of ice at the downstream end of glaciers. The researchers found ice shelves are losing mass in West Antarctica, where many of the continent's fastest-moving glaciers are located as well, according to NASA.
NASA explains that ice that melts from ice shelves doesn't raise sea levels, since it's already floating -- just like an ice cube already in a full cup of water doesn't overflow the glass when it melts. But the ice shelves provide stability for the glaciers and ice sheets behind them.
"It's like an architectural buttress that holds up a cathedral," says Helen Amanda Fricker, a glaciologist at the Scripps Institution of Oceanography at the University of California San Diego, and co-author of the Science paper.
She told NASA, "The ice shelves hold the ice sheet up. If you take away the ice shelves, or even if you thin them, you're reducing that buttressing force, so the grounded ice can flow faster."
This study was conducted over 16 years and published online in Science April 30.