Greenland and Antarctic ice sheets experience 'devastating' melting, researchers discover.

April 20, 2023

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by Seth Borenstein

According to a new comprehensive international study, both the Greenland and Antarctic ice sheets are losing over three times more ice per year than they were 30 years ago.

Utilizing 50 different satellite estimates, researchers found that Greenland's melt has gone into overdrive in recent years. Greenland's average annual melt from 2017 to 2020 was 20% higher than at the beginning of the decade and over seven times greater than its annual shrinkage in the early 1990s.

Study co-author Ruth Mottram, a climate scientist at the Danish Meteorological Institute, states that the new figures are "pretty disastrous really." She adds, "We're losing more and more ice from Greenland."

Lead author of the study, Ines Otosaka, a glaciologist at the University of Leeds, asserts that the sped-up ice loss is unequivocally due to human-caused climate change.

From 1992 to 1996, the two ice sheets which contain 99% of the world's freshwater ice were diminishing by 116 billion tons (105 billion metric tons) per year, with two-thirds of this coming from Antarctica.

However, from 2017 to 2020, the newest available data, the combined melt soared to 410 billion tons (372 billion metric tons) each year, with over two-thirds of it from Greenland, as per the study in Thursday's journal Earth System Science Data.

"This is a devastating trajectory," says Twila Moon, Deputy Lead Scientist at the U.S. National Snow and Ice Center, who was not involved in the study. "These rates of ice loss are unprecedented during modern civilization."

The study found that between 1992 and 2023, the Earth has lost 8.3 trillion tons (7.6 trillion metric tons) of ice from the two ice sheets. This amount is enough to flood the entire United States with almost 0.9 meters of water or inundate France in nearly 15 meters.

However, the melt just from the ice sheets since 1992 only accounts for less than an inch (21 millimeters) of sea level rise, on average, because the world's oceans are so vast. Globally, sea level rise is accelerating, and the study shows that the contribution from melt from ice sheets has increased from 5% to over one-quarter. The remainder of the sea rise comes from the expansion of warmer water and melt from glaciers.

The study is funded by NASA and the European Space Agency, and a team of over 65 scientists regularly calculates ice sheet loss, with Thursday's study providing three additional years of data. According to Otosaka, the team uses 17 different satellite missions and examines ice sheet melt in three distinct techniques, with all the satellite data, radar, on-the-ground observations, and computer simulations confirming that ice sheet melting is accelerating.

Greenland from 2017 to 2020 averaged approximately 283 billion tons (257 billion metric tons) of melting annually, compared with 235 billion tons (213 billion metric tons) each year from 2012 to 2016.

The most recent data appears to show a reduction in melting in some parts of Antarctica, which has much more ice than Greenland. However, that is mostly due to smaller and fleeting weather changes, and the overall longer-term trend indicates an acceleration of melting in Antarctica, states Mottram.

Antarctica from 2017 to 2020 still loses about 127 billion tons (115 billion metric tons) of ice each year, which is 23% less than earlier in the decade but 64% greater than in the early 1990s.

Mark Serreze, Director of the U.S. Snow and Ice Center, who was not part of the study, says that "while mass loss from Greenland is outpacing that from Antarctica, there are troublesome wild cards in the south, notably behavior of the Thwaites glacier," which is nicknamed the Doomsday Glacier.

The study measured changes in gravity and ice height, the amount of snowfall, the amount of snow that melted, and how much ice was lost through icebergs calving and erosion from underneath caused by warmer water etching, according to the study authors.

"This matters because rising sea levels will displace and/or financially impact hundreds of millions of people, if not billions, and will likely cost trillions of dollars," says former NASA chief scientist and current University of Colorado ice researcher Waleed Abdalati, who was not part of the study.

The study 'is not so much surprising as it is disturbing,' Abdalati said in an email 'A few decades ago, it was assumed that these vast reservoirs of ice changed slowly, but with through the use of satellite observations, field observations and modeling techniques, we have come to learn that ice responds rapidly to our changing climate.'

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