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A satellite mission that bounces laser light off the Antarctic and Greenland ice sheets discovered that hundreds of billions of tons of ice are lost each year due to Earth’s climate change.
Scientists involved in NASA’s ICESat-2 project report in the journal Science that the net loss of ice from those regions has been responsible for 0.55 inches of sea level rise since 2003. That’s just under a third of the total amount of increase observed. in the world’s oceans during that time.
To track how the ice sheets are changing, the ICESat-2 team compared the satellite’s laser scans with similar measurements that were taken by the original ICESat spacecraft from 2003 to 2009. (ICESat stands for “Ice, Cloud, and Elevation Satellite” ).
“If you look at a glacier or ice cap for a month or a year, you won’t learn much about the weather,” said Ben Smith, a glaciologist at the University of Washington and lead author of the publication. Scientific document said in a NASA press release. “We now have a 16 year gap between ICESat and ICESat-2 and we can be much more confident that the changes we are seeing on the ice have to do with long-term changes in the climate.”
ICESat-2 was launched in 2018 to begin what is expected to be a three-year scientific mission. The satellite’s laser altimeter sends 10,000 pulses of light to Earth’s surface every second, and the time it takes for the reflected pulses to return. The pulse rate, measured to an accuracy that is within one billionth of a second, is interpreted to produce high-precision measurements of the elevation of an ice sheet.
Scientists can track how those measurements change over the course of a year to an inch. For the Science study, they entered the ICESat and ICESat-2 readings into a computer model that converted changes in volume to changes in mass.
Smith and his colleagues discovered that the ice sheets are thickening in the interior of Antarctica and Greenland, probably due to increased snowfall. But in both cases, the increase in ice inside is much greater than the loss in ice around the edges.
The Greenland ice sheet lost an average of 200 billion tons of ice per year, while the Antarctic ice sheet had an annual loss of 118 billion tons of ice, the research team reported. A billion tons of ice represents enough water to fill 400,000 Olympic pools.
“These early results analyzing land ice confirm the consensus of other research groups, but also allow us to see the details of the change in individual glaciers and ice shelves at the same time,” said Tom Neumann, ICESat-2 project scientist at The NASA. Goddard Space Flight Center.
In Antarctica, the main areas for ice loss are West Antarctica and the Antarctic Peninsula, where the warmer seas are melting ice. In Greenland, the Kangerlussuaq and Jakobshavn glaciers have lost 14-20 feet of elevation per year due to the warmer summer temperatures.
The researchers also studied the floating ice shelves around Antarctica, which are more difficult to track because they rise and fall with the tides. A detailed analysis of the ICESat-2 data found that the Thwaites and Crosson ice shelves in West Antarctica have become thinner, losing an average of 16 feet and 10 feet per year, respectively.
“What we expect by the turn of the century is on the order of 2, 3, maybe 4 feet elevation from sea level,” said Alex Gardner, a glaciologist at NASA’s Jet Propulsion Laboratory, in a video about the study. “Because we have all of our infrastructure built around the coasts, we are highly vulnerable to a gauge change in sea level rise.”
The Science study, “Mass Loss of the General Ice Sheet Reflects Competitive Ocean and Atmospheric Processes,” was funded by NASA. In addition to Smith and Neumann, the co-authors are Helen Fricker, Alex Gardner, Brooke Medley, Johan Nilsson, Fernando Paolo, Nicholas Holschuh, Susheel Adusumilli, Kelly Brunt, Bea Csatho, Kaitlin Harbeck, Thorsten Markus, Matthew Siegfried, and H. Jay Zwally.
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