By Saarang Kashyap
NASA satellites have provided crucial data on what has been happening to Antarctica and Greenland’s ice over the past several years: billions of tons of ice have melted and are currently adding to rising sea levels that threaten coastal cities.
Boyle, at Independent, reports that the “findings were based on information from the space agency’s ICESat and ICESat-2 satellite laser altimeters – devices that use laser pulses to measure the elevation and thickness of ice sheets and help better understand global climate change. These devices demonstrated a small increase in ice thickening in East Antarctica, but a significant loss in ice around West Antarctica and the Antarctic Peninsula. Patterns of thinning over the ice shelves in West Antarctica show that Thwaites and Crosson ice shelves have thinned the most, an average of about 16 feet (5 meters) and 10 feet (3 meters) of ice per year, respectively.”
According to NASA, “the satellites also found that Greenland’s ice sheet lost an average of 200 gigatons of ice per year, and Antarctica’s ice sheet lost an average of 118 gigatons of ice per year. One gigaton of ice is enough to fill 400,000 Olympic-sized swimming pools or cover New York’s Central Park in ice more than 1,000 feet (300 meters) thick, reaching higher than the Chrysler Building.”
The mission is also shedding light on what’s driving the melting. Antarctica’s ice, now sitting on land, makes a slow progression to the ocean. When it reaches the coast, it floats, creating ice shelves that skim around the coasts. These shelves act as barriers that slow the rate of ice loss, but as they melt in a warming ocean, that barrier is shrinking. “It’s like an apple tart and the ice shelves are like the wall of pastry around the edges of the tart,” says Fricker. “And if those walls are too thin or they’re not baked well enough, then the filling will ooze out.”
While ice that melts from ice shelves does not directly lead to rising sea levels, they provide stability to the glaciers and ice sheets beneath them. Thus, taking away these ice shelves leads to grounded ice flowing faster, which does contribute to increasing sea levels.