October 3, 2022
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Satellite imagery shows Antarctic ice shelf crumbling much faster than initially thought

Satellite imagery shows Antarctic ice shelf crumbling much faster than initially thought

LOS ANGELES — Antarctica’s coastal glaciers are shedding icebergs extra quickly than nature can replenish the crumbling ice, doubling earlier estimates of losses from the world’s largest ice sheet over the previous 25 years, a satellite tv for pc evaluation confirmed on Wednesday.

The primary-of-its-kind examine, led by researchers at NASA’s Jet Propulsion Laboratory (JPL) close to Los Angeles and revealed within the journal Nature, raises new concern about how briskly local weather change is weakening Antarctica’s floating ice cabinets and accelerating the rise of worldwide sea ranges.

The examine’s key discovering was that the online lack of Antarctic ice from coastal glacier chunks “calving” off into the ocean is sort of as nice as the online quantity of ice that scientists already knew was being misplaced attributable to thinning attributable to the melting of ice cabinets from beneath by warming seas.

Taken collectively, thinning and calving have diminished the mass of Antarctica’s ice cabinets by 12 trillion tons since 1997, double the earlier estimate, the evaluation concluded.

The web lack of the continent’s ice sheet from calving alone up to now quarter-century spans practically 37,000 sq km, an space virtually the dimensions of Switzerland, in accordance with JPL scientist Chad Greene, the examine’s lead writer.

“Antarctica is crumbling at its edges,” Mr. Greene mentioned in a NASA announcement of the findings. “And when ice shelves dwindle and weaken, the continent’s massive glaciers tend to speed up and increase the rate of global sea level rise.”

The results might be monumental. Antarctica holds 88% of the ocean degree potential of all of the world’s ice, he mentioned.

Ice cabinets, everlasting floating sheets of frozen freshwater hooked up to land, take hundreds of years to type and act like buttresses holding again glaciers that might in any other case simply slide off into the ocean, inflicting seas to rise.

When ice cabinets are secure, the long-term pure cycle of calving and re-growth retains their measurement pretty fixed.

In current many years, although, warming oceans have weakened the cabinets from beneath, a phenomenon beforehand documented by satellite tv for pc altimeters measuring the altering peak of the ice and displaying losses averaging 149 million tons a 12 months from 2002 to 2020, in accordance with NASA.

For his or her evaluation, Mr. Greene’s workforce synthesized satellite tv for pc imagery from seen, thermal-infrared and radar wavelengths to chart glacial circulate and calving since 1997 extra precisely than ever over 30,000 miles (50,000 km) of Antarctic shoreline.

The losses measured from calving outpaced pure ice shelf replenishment so vastly that researchers discovered it unlikely Antarctica can return to pre-2000 glacier ranges by the tip of this century.

The accelerated glacial calving, like ice thinning, was most pronounced in West Antarctica, an space hit tougher by warming ocean currents. However even in East Antarctica, a area whose ice cabinets had been lengthy thought of much less weak, “we’re seeing more losses than gains,” Mr. Greene mentioned.

One East Antarctic calving occasion that took the world abruptly was the collapse and disintegration of the huge Conger-Glenzer ice shelf in March, probably an indication of higher weakening to return, Mr. Greene mentioned.

Eric Wolff, a Royal Society analysis professor on the College of Cambridge, pointed to the examine’s evaluation of how the East Antarctic ice sheet behaved throughout heat intervals of the previous and fashions for what might occur sooner or later.

“The good news is that if we keep to the 2 degrees of global warming that the Paris agreement promises, the sea level rise due to the East Antarctic ice sheet should be modest,” Mr. Wolff wrote in a commentary on the JPL examine.

Failure to curb greenhouse fuel emissions, nonetheless, would danger contributing “many meters of sea level rise over the next few centuries,” he mentioned. — Reuters

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