IRVINE, California — About 12.5 trillion tons of ice from the Greenland and Antarctic glaciers have melted since 1979, which is enough frozen water to pack ice 5 feet deep across the entire continental United States, according to a major scientific report. Earth’s warming is accelerating the melting of the planet’s two main ice sheets, and five-sixths of the melt comes not from warmer air but from warmer waters eating away at the ice sheets from below and sides, with glaciers flowing into the oceans, according to a study published Wednesday in the journal Scientific Data. That’s bad news for future sea level rise, the study authors said. “The ice sheets are melting rapidly,” said study co-author Eric Rignot, an ice scientist at the University of California, Irvine. “We are melting the polar regions; sea levels are rising around the world and will exacerbate the vulnerability of coastal regions.” The numbers behind the melt are staggeringly huge and deceptively small. All that melted ice became nearly 3 trillion gallons of water, raising global sea levels about an inch since 1979, in addition to other climate factors raising the height of the oceans, according to the report. An inch may not seem like a lot, but for every third of an inch (or centimeter) of sea level rise, another 2 to 3 million people are flooded at least once a year, said the study’s lead author, Ines Otosaka, an ice scientist at Northumbria University in England. The Jakobshavn Glacier in Greenland is retreating up to 164 feet a day, Otosaka said. But by incorporating NASA satellites, scientists were able to plot the volumes of ice sheets in Antarctica from 1979 and in Greenland to 1972. “There is a clear trend that the ice sheets are losing more mass, and it has been increasing from decade to decade, especially if you look at the ice that is discharged into the ocean,” Otosaka said. “And that’s pretty clear that there is a link to climate change.” It showed that in the 1970s, 1980s and 1990s, the ice sheets were relatively stable, but then melting began, and it really occurred during the 2010s, Otosaka said. “We need to stop warming the planet,” said study co-author Andrew Shepherd, also from Northumbria. The accelerating numbers appeared to stop from 2020 to 2023, but the study’s authors said it reflected more short-term climate variations than long-term trends. Otosaka said the study stopped with data from 2023, but examined measurements since then and found that the accelerating trend has recovered. Much of the stability in Antarctica came because East Antarctica had record snowfall, which offset rapid melting in the less stable West Antarctic ice sheet, the authors said. The three-year hiatus was “just an increase in the record,” Rignot said. “The prolonged rise is the climate and the threat is very clear.” The biggest changes the scientists observed are in what they call dynamic processes, which are more abrupt and active than the slow, steady melting of air, and that’s something prone to triggering runaway “tipping points,” Otosaka said. New York University ice scientist David Holland said that’s what worries him “because most ice loss is dynamic and that’s exactly what would be expected in an ice sheet instability collapse scenario.” The international team used 45 independent studies and 27 different satellites. “Using relatively independent methods gives me greater confidence in the result,” said Holland, who was not part of the study. “The upward trend is real.” “The ‘wild cards’ of Antarctic mass loss continue to pose a challenge to human management of the planet: a clear and present danger, but many decades in the future,” said University of Colorado ice scientist Ted Scambos, who was not part of the study. “We are now a society smart enough to know the future, but not prudent enough to act on the knowledge.” The Associated Press’ climate and environmental coverage receives financial support from multiple private foundations. AP is solely responsible for all content. Find AP’s standards for working with philanthropic organizations, a list of supporters and funded coverage areas at AP.org. Key findings in this article were generated with the help of large language models and reviewed by our editorial team. The article itself is written solely by humans.
