Antarctica Gained Five Years' Worth of Ice in Less Than Two. The Cause Was Thousands of Miles Away.

Between July 2021 and April 2023, Antarctica gained roughly 695 billion metric tons of ice-sheet mass. After decades of net losses, the continent had briefly gone into reverse. The reason was sitting thousands of miles away, in unusually warm tropical ocean water.

The gain was the largest 22-month increase recorded by the GRACE gravity satellites. Most of it accumulated in East Antarctica, particularly along the Queen Mary Land–Wilkes Land coast, where exceptional snowfall more than offset continuing ice losses elsewhere on the continent.

Researchers traced the event to sustained warming in the tropical warm pool, where the western Pacific meets the eastern Indian Ocean. The warming triggered a Rossby wave train, a large-scale ripple in atmospheric circulation that traveled toward Antarctica and helped establish an unusual pressure pattern over the continent.

That pattern changed the routes taken by moisture-laden air. More atmospheric rivers carried water vapor from the midlatitude Indian Ocean toward East Antarctica, where it fell as snow. The tropical warm pool was the trigger, not the direct source of the extra moisture. It changed the delivery route.

The scale is difficult to overstate. Antarctica lost an average of about 140.5 billion metric tons of ice per year from 2003 to 2024. The 695-billion-ton gain was equivalent to nearly five years of losses at that rate. Yet West Antarctica continued losing ice, and the researchers say the gain was probably temporary rather than a reversal of the long-term trend.

Similar periods of sustained tropical warm-pool warming occur roughly once a decade. The researchers identified the atmospheric mechanism behind that event, but how this recurring connection will behave as the climate changes remains an important question.

Antarctica's weather has a remote control in the tropics. The snow, however, arrives from somewhere else.

Read the full story at Nature, August 19, 2026

Hot Take: Glacial retreat is hard enough to model without Antarctica occasionally deciding to put the ice back.