Earth lost 12.5 trillion tons of ice from major ice sheets since 1979, report says

Earth has lost approximately 12.5 trillion tons of ice from its Greenland and Antarctic ice sheets since 1979, according to a major scientific report. This vast amount of melted ice is enough to cover the continental United States in a layer of water 5 feet deep.

The study, published in the journal Scientific Data, indicates that a warming planet is accelerating the melting of these two major ice sheets. Contrary to some assumptions, five-sixths of this ice loss is attributed not to warmer air temperatures, but to warmer ocean waters eroding the ice sheets from below and along their edges as glaciers flow into the sea.

Scientists involved in the study expressed concern about the implications for future sea level rise. "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."

The total volume of melted ice equates to nearly 3 quadrillion gallons of water, which has contributed to a global sea level rise of about 1 inch (3.1 centimeters) since 1979, in addition to other climate-related factors. Lead author Ines Otosaka, an ice scientist at Northumbria University in England, highlighted the impact of this rise, noting that for every third of an inch of sea level increase, an additional two to three million people face annual flooding.

This extensive analysis, conducted by an international collaboration of polar scientists led by the European Space Agency, incorporated data from NASA satellites alongside previous European satellite information. This allowed researchers to chart ice sheet volumes in Antarctica as far back as 1979 and in Greenland to 1972. Previously, studies often focused only on data from the 1990s onwards.

Otosaka observed a clear trend: "The ice sheets are losing more mass and it has been increasing from decade to decade, especially if you look at the ice being discharged to the ocean. And that’s quite clear that there’s a link to climate change."

The data revealed that while the ice sheets were relatively stable through the 1970s, 1980s, and into the 1990s, melting began to accelerate, particularly in the 2010s. "That’s something to be concerned about as it shows that the changes are tracking decades behind global warming, which means we can expect them to continue for decades more — even if we are able to stop heating the planet," said co-author Andrew Shepherd, also of Northumbria.

While the rate of ice loss appeared to pause between 2020 and 2023, the authors suggest this was due to short-term weather variations rather than a long-term trend. Otosaka noted that preliminary data since 2023 indicates the accelerating trend has resumed.

The study also pointed to regional differences, with East Antarctica experiencing record snowfall that partially offset rapid melting in the less stable West Antarctic Ice Sheet. Rignot described the recent hiatus as "just a bump in the record," emphasizing that "The long rise is climate and the threat is crystal clear."

Scientists are particularly concerned about "dynamic processes" – abrupt and active changes in ice sheet behavior – as these are more prone to triggering runaway "tipping points." NYU ice scientist David Holland, who was not part of the study, shared this concern, stating that "most of the ice loss is dynamical and that is exactly what you would expect in an ice sheet instability collapse scenario."

The international team utilized data from 45 independent surveys and 27 different satellites. The congruence of these varied methods, according to Holland, increases confidence in the findings, confirming that "The upward trend is real."

University of Colorado ice scientist Ted Scambos, also not involved in the study, commented on the long-term implications: "The ‘wild cards’ of Antarctic mass loss continue to pose a challenge for human management of the planet — a clear and present danger, but many decades in the future." He added, "We are now as a society smart enough to know the future, but not prudent enough to act upon the knowledge."