It turns out a glacier in western Antarctica has been melting since the 1940s, according to a new study by South Pole experts.
Pine Island Glacier began warming in the 1940s due to a naturally-occurring El Nino warming event, the British Antarctic Survey (BAS) found in a new study. The organization’s work suggests western Antarctic glacial melt began 30 years before the the global warming trend that started in the late 1970s.
What’s even more interesting is Pine Island Glacier continued to melt even when global average surface temperature cooled over the next three decades. NASA data shows 1944 was the warmest year on record globally until 1980.
“A significant implication of our findings is that once an ice sheet retreat is set in motion it can continue for decades, even if what started gets no worse,” NASA’s Bob Bindschadler said in a statement.
“It is possible that the changes we see today on Pine Island Glacier were essentially set in motion in the 1940s,” said Bindschadler, one of the study’s co-authors.
Scientists have been warning of Pine Island’s melting rate since the early 1990s, with many attributing its reportedly increasing melt rate to man-made global warming. But the BAS study is the first to look into what caused it to melt.
The BAS team obtained sediment samples by drilling by hand more than 3,280 feet through ice to try and figure out when Pine Island began its melt. Scientists now use satellites to track glaciers, but those records only go back to the early 1980s.
BAS experts say Pine Island has been a major contributor to global sea level rise in recent decades, and other researchers have argued Pine Island’s collapse could help set in motion the collapse of the entire west Antarctic ice sheet.
“Understanding what initiated the current changes is one major piece of the jigsaw, and now we are already looking for the next—how long will these changes continue and how much ice will Pine Island Glacier and its neighbours lose in the coming century?” David Vaughn, BAS’s director of science, said.
Despite warnings, it’s unclear exactly what role global warming has played in Antarctica in recent decades. Scientists say they’ve had trouble finding signs of man-made warming over the “noise” of natural variability in the region. While the Arctic ice cap has been shrinking since the 1980s, some research suggests Antarctica’s ice sheet gained mass since the 1990s.
A 2015 study by NASA found Antarctica’s ice sheet increased in mass from 1992 to 2008. The study found ice gains in Eastern antarctica more than offset ice loss from melting glaciers in the west.
Past research has also found western Antarctica sits atop subterranean volcanoes, which may be contributing to its instability in recent decades.
University of Texas-Austin researchers used radar techniques to map water flows under ice sheets and estimate the rate of ice melt in the glacier. They found geothermal heat from magma and volcanoes under the glacier is much hotter and covers a much wider area than was previously thought.
The Thwaites Glacier in western Antarctica is being eroded by the ocean as well as geothermal heat from magma and subaerial volcanoes, UTA researchers found.
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