That warming generated what scientists call a Rossby wave train — a large-scale pattern of atmospheric waves that can transmit changes in weather across enormous distances, from the tropics to the high southern latitudes.

Feedbacks in the atmosphere, known as eddy mean flow feedbacks, strengthened and prolonged the resulting circulation pattern. The outcome was a north–south pressure dipole: unusually low pressure south of Australia and unusually high pressure along the East Antarctic coast.

This pressure configuration rerouted moisture in the atmosphere. Specifically, it strengthened the transport of water vapor from the midlatitude Indian Ocean toward East Antarctica.

Atmospheric rivers delivered the snow

Atmospheric rivers are relatively narrow corridors in the atmosphere that carry huge amounts of water vapor over long distances. When they reach cold regions like Antarctica, that moisture falls as heavy snow.

Water vapor tracking simulations showed that the dipole circulation funneled moist air from the midlatitude Indian Ocean toward East Antarctica and allowed more atmospheric rivers to reach the continent. The result was sustained heavy snowfall across the Queen Mary Land–Wilkes Land region, adding substantial mass to the ice sheet.

Atmospheric circulation model experiments backed up the picture: warming of the tropical warm pool directly drove both the circulation changes and the increase in snowfall.

The researchers also tested how much of the snowfall increase could be attributed to human-driven climate forcing. The answer was small — equivalent to only 9% of the observed snowfall anomaly. In other words, the general increase in atmospheric moisture that comes with global warming was not the main explanation for this particular event. The dominant factor was the tropical ocean's influence on circulation.

A remote 'regulator' for Antarctic ice

Additional observations and simulations suggest that comparable periods of sustained warming in the tropical warm pool occur roughly once every decade. The researchers therefore describe the tropical warm pool as a remote "regulator" capable of influencing snowfall and ice mass in East Antarctica over periods lasting several years.

"We found a previously underrecognized 'tropical warm pool–East Antarctic Ice Sheet' teleconnection pathway," said Yunhe Wang of IOCAS, the study's first author. "Our research provides a theoretical basis for understanding Antarctic ice-sheet mass changes and conducting future research on the East Antarctic climate."

The study identifies the north–south dipole circulation over East Antarctica as the key link connecting tropical climate conditions to changes in Antarctic ice mass.

The long-term picture hasn't changed

Despite the striking 695-billion-ton gain, the researchers are clear about its limits. The event was temporary and does not reverse the long-term decline of the Antarctic Ice Sheet.

The West Antarctic Ice Sheet continues to lose mass. In East Antarctica, some outlet glaciers also remain vulnerable: warm ocean water melts their ice shelves from below, speeding up the flow of ice toward the sea.

What the findings do offer is a clearer picture of how the climate system connects distant regions. Conditions in the tropical ocean can, through waves in the atmosphere and rivers of moisture, have major consequences for how much snow falls on the far side of the planet.