Satellites Reveal 12.5 Trillion Tons of Ice Lost from Polar Sheets Since 1979

Greenland and Antarctica have shed about 12.5 trillion tons (11.3 trillion metric tons) of ice since 1979, enough frozen water to cover the continental United States in a five-foot-deep layer, according to a major scientific assessment published in the journal Scientific Data.

The international team of polar scientists, led by the European Space Agency, combined NASA satellite records with European data to extend the ice-sheet record back to 1979 for Antarctica and 1972 for Greenland. The study drew on 45 independent surveys and 27 different satellites.

All that meltwater — nearly 3 quadrillion gallons (11.3 quadrillion liters) — has raised global sea levels by about an inch (3.1 centimeters) since 1979, on top of other climate-driven factors. The authors note that for every additional centimeter of sea-level rise, another 2 to 3 million people face flooding at least once a year.

Five-sixths of the ice loss did not come from hotter air but from warmer ocean waters eroding the ice sheets from below and the sides, with glaciers flowing into the sea. The Jakobshavn glacier in Greenland is now retreating by as much as 164 feet (50 meters) a day, according to lead author Ines Otosaka of Northumbria University.

The record shows the ice sheets were relatively stable through the 1970s, 1980s and into the 1990s, before melt set in and accelerated sharply during the 2010s. A pause in the accelerating trend between 2020 and 2023 reflected short-term weather variability rather than a change in the long-term trajectory, the authors said, adding that more recent measurements show the trend has resumed.

Much of Antarctica's apparent stability came from record snowfall in East Antarctica, which offset rapid melting in the less stable West Antarctic Ice Sheet.

"The ice sheets are melting away fast," said co-author Eric Rignot, an ice scientist at the University of California, Irvine. "We are melting the polar regions, sea level is rising worldwide and will exacerbate the vulnerability of coastal regions."

Co-author Andrew Shepherd, also of Northumbria University, said the changes are tracking decades behind global warming, meaning they can be expected to continue for decades even if planetary heating is halted.

The study highlights dynamic processes — more abrupt and active than slow melting from air temperatures — as the biggest changes observed, a pattern that scientists outside the study said is consistent with ice-sheet instability. David Holland of New York University called the upward trend real, while Ted Scambos of the University of Colorado described Antarctic mass loss as a clear and present danger many decades in the future.