Antarctica is now losing six times more ice annually than it did just 40 years ago, according to a new study by glaciologists from the University of California, Irvine (UCI), NASA's Jet Propulsion Laboratory (JPL) and the Netherlands' Utrecht University.
The study, whose findings are published in the Proceedings of the National Academy of Sciences (PNAS), is based on the longest-ever assessment of the remaining ice mass in Antarctica, spanning four decades from 1979 until 2017.
"That's just the tip of the iceberg, so to speak," said Eric Rignot, Donald Bren Professor and chair of Earth system science at UCI, and the lead author of the study paper.
In the study, researchers examined 18 regions covering 176 basins and the surrounding islands in Antarctica. The team analysed high-resolution images captured by NASA's Operation IceBridge as well as radar interferometry data gathered by the satellites of multiple space agencies. Data from the on-going Landsat satellite imagery series was also examined.
The team estimated ice sheet balance by comparing snowfall accumulation in interior basins with ice discharge by glaciers at their grounding lines.
The results revealed that Antarctica lost an average of 40 gigatons of ice mass per year from 1979 and 1990 and about 252 gigatons per year from 2009 to 2017.
The rate of melting also increased dramatically from an average of 48 gigatons annually per decade from 1979 to 2001 to 134 gigatons from 2001 to 2017.
A surprising finding was to know that East Antarctica's Wilkes Land sector has always significantly participated in ice mass loss, even in the 1980s. This specific region holds more ice than the combined ice mass of West Antarctica and the Antarctic Peninsula, and is likely more sensitive to climate changes than earlier thought.
These results appear at a time when another study, published in journal Nature Geosciences, found that variations in the axial tilt of Earth significantly affect the rise and fall of the Antarctic Ice Sheet.
This particular study reviewed the history of the Antarctic Ice Sheet over the past 34 million years, and was able to match it with the periodic astronomical motions of the Earth.
The study, which was led by Stephen Meyers of the New Zealand's University of Wisconsin-Madison and Richard Levy of the GNS Science, suggests that loss of sea ice due to climate change could possibly intensify the cyclic effects of the Earth's obliquity on the ice sheet as ocean waters warm.
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