New research on Antarctica doubles the previous estimates of loss from ice shelves and details how the continent is changing.
The greatest uncertainty in forecasting global sea level rise is not knowing the degree of ice loss or the acceleration timeline as climare change continues.
However, not one, but two studies published Aug. 10 and led by researchers at NASA’s Jet Propulsion Laboratory in Southern California reveal unexpected new data about how the Antarctic Ice Sheet has been losing mass in recent decades.
One study, published in the journal Nature, maps how iceberg calving – the breaking off of ice from a glacier front – has changed the Antarctic coastline over the last 25 years.
This study also raises concerns over how fast climate change is weakening Antarctica’s floating ice shelves and accelerating the rise of global sea levels.
The key finding in this particular study is that the net loss of Antarctic ice from coastal glacier chunks “calving” off into the ocean is nearly as great as the net amount of ice that scientists already knew was being lost due to thinning caused by the melting of ice shelves from below by warming seas.
It is estimated that thinning and calving have reduced the Antarctic’s ice shelves by 12 trillion tons since 1997, double the previous estimate, the analysis concluded.
The second study. published in Earth System Science Data, shows in unprecedented detail how the thinning of Antarctic ice as ocean water melts it has spread from the continent’s outward edges into its interior, almost doubling in the western parts of the ice sheet over the past decade.
It goes wit6hout saying that the two studies cpmpliment each other in giving a very clear and concise overview into what is happening in Antarctica.
“Antarctica is crumbling at its edges,” said JPL scientist Chad Greene, the study’s lead authot 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 consequences could be enormous. Antarctica holds 88 percent of the sea level potential of all the world’s ice, he said.
It has taken thousands of years for the frozen, floating permenent .ice shelves to form, and they act like a buttress or dam, holding back the glaciers that would otherwise slide on into the seas.
When ice shelves are stable, the long-term natural cycle of calving and re-growth keeps their size fairly constant. However, in recent years, warming oceans have weakened the shelves from underneath, a phenomenon previously documented by satellite altimeters measuring the changing height of the ice and showing losses averaging 149 million tons a year from 2002 to 2020, according to NASA.
The bottom line in all this data clearly shows that failure to curb greenhouse gas emissions now will be humanity’s undoing.
