Antarctic ice sheet gains 695 billion tonnes, but warming reversal is not underway

Antarctica’s ice sheet gained about 695 billion tonnes over 22 months, an extraordinary increase that could easily be mistaken for a sign of recovery. Researchers say it is not. The change resulted mainly from unusual snowfall in East Antarctica after warming in tropical waters altered atmospheric circulation.

An international team from the Institute of Oceanology of the Chinese Academy of Sciences and the University of California, Santa Barbara analyzed data from the GRACE and GRACE-FO satellites, which measure changes in ice mass through variations in gravity. From 2003 to 2024, the Antarctic ice sheet lost an average of 140.5 billion tonnes a year. Between July 2021 and April 2023, however, its mass increased by about 695 billion tonnes, the largest rise in the satellite record covering more than two decades.

Most of the increase occurred in East Antarctica. Queen Mary Land and Wilkes Land gained about 470.3 billion tonnes, or roughly 68 percent of the total. Some parts of West Antarctica continued losing ice during the same period.

The researchers traced the snowfall to the Tropical Warm Pool, where the western Pacific meets the eastern Indian Ocean. Sea surface temperatures there remained unusually high between 2021 and 2023. The warmer ocean generated large Rossby waves in the atmosphere, changing circulation over East Antarctica. A stronger low-pressure system formed south of Australia while high pressure developed along the East Antarctic coast, redirecting moisture from the mid-latitude Indian Ocean.

Atmospheric rivers carried more water vapor toward East Antarctica. When that moisture reached the continent’s extreme cold, it produced heavy snowfall that accumulated on the ice sheet, especially in Queen Mary Land and Wilkes Land. The team compared satellite gravity observations with climate reanalysis data, ice-core records and atmospheric circulation models.

The researchers said human-caused warming accounted for only about 9 percent of the observed cumulative precipitation anomaly in the two regions. Similar long-term warming in the Tropical Warm Pool appears roughly once every 10 years. Despite the temporary gain, Antarctica’s long-term ice loss continues, with warm seawater melting ice shelves from below in West Antarctica and some outlet glaciers in East Antarctica remaining vulnerable. Lead author Wang Yunhe said the study identified a previously underappreciated teleconnection between the tropical warm pool and the East Antarctic ice sheet.

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We discovered a teleconnection pathway between the tropical warm pool and the East Antarctic ice sheet that had not been sufficiently recognized.