New satellite images coming from NASA’s Jet propulsion laboratory (JPL) near Los Angeles on Wednesday have shown that Antarctica’s coastal ice shelfs are crumbling twice as fast as previously estimated. Over the past 25 years the continents ice sheets have...
Antarctica losing ice faster than previously thought
New satellite images coming from NASA’s Jet propulsion laboratory (JPL) near Los Angeles on Wednesday have shown that Antarctica’s coastal ice shelfs are crumbling twice as fast as previously estimated.
Over the past 25 years the continents ice sheets have been collapsing faster than nature can replenish the melting ice, doubling the previous estimates of losses from experts and raising fresh concerns on how quickly climate change is weakening Antarctica’s ice shelf and accelerating the sea levels around the world.
The main conclusion of the research stated that the total loss of Antarctic ice from chunks of coastal glaciers "calving" off into the ocean is approximately as great as the net loss of ice that scientific researchers already knew was happening due to thinning caused by melting of ice shelves from below by rising temperatures of the seas.
The investigation found that thinning and calving, when combined, have decreased the bulk of Antarctica's ice shelves by 12 trillion tonnes since 1997, which is twice the prior estimate.
According to JPL scientist Chad Greene, the study's principal author, the continent's ice sheet has lost about 37,000 sq km (14,300 sq miles) of its total surface during the previous 25 years due to calving alone, an area that is almost the size of Switzerland.
In a NASA press release announcing the findings, Greene stated that "Antarctica is collapsing at its edges." 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."
There may be severe repercussions. According to Greene, 88% of the world's ice could raise the sea level.
It takes thousands of years for ice shelves, which are permanently floating sheets of frozen freshwater tied to land, to form. Once formed, they function as buttresses to hold back glaciers that would otherwise readily slip into the ocean, raising sea levels.
The long-term natural cycle of calving and regrowth regulates the extent of ice shelves when they are stable.
However, in recent decades, warmer oceans have damaged the shelves from below. This phenomena has already been observed by satellite altimeters, which track changes in the height of the ice. According to NASA, losses from 2002 to 2020 averaged 149 million tonnes per year.
Greene's team's research used satellite photos from visible, thermal-infrared, and radar wavelengths to more precisely record glacier flow and calving since 1997 from over 30,000 miles of Antarctica’s coastline.
Researchers concluded that it is doubtful Antarctica will reach the glacier levels of before 2000 by the end of this century because the losses from calving surpassed natural ice shelf replacement by a significant margin.
West Antarctica, which is a region more severely affected by rising ocean currents, saw the most apparent acceleration of glacial calving, as well as ice thinning. Greene said that even in East Antarctica, where the ice shelves were once thought to be less fragile, "we're witnessing more losses than gains."
The vast Conger-Glenzer ice shelf's collapse and disintegration in March, probably a hint of further weakening to come, was one East Antarctic calving event that caught everyone off guard.
A Royal Society research professor at the University of Cambridge named Eric Wolff cited the study's examination of past patterns of behaviour of the East Antarctic ice sheet during warm periods as well as predictions for potential future outcomes.
"The good news is that the sea level rise owing to the East Antarctic ice sheet should be limited if we stay to the 2 degrees global warming that the Paris agreement pledges," Wolff wrote in a commentary on the JPL study.
However, he warned that failure to reduce greenhouse gas emissions ran the risk of causing "several metres of sea level rise over the next few centuries."