‘Help’ for Antarctica Came from Thousands of Kilometres Away

Changes in the mass of the Antarctic Ice Sheet can be influenced by numerous factors, including climate events occurring thousands of kilometres away. At the same time, changes in the Southern Ocean and Antarctica themselves affect the global climate: through the carbon cycle and by absorbing a substantial proportion of the warming, they influence the processes of climate change. Antarctica is therefore one of the key regions of the Earth in terms of climate change. Surprisingly, however, between 2021 and 2023, ice-sheet mass gain in East Antarctica exceeded the losses occurring in West Antarctica, slowing the overall rate of ice mass loss. Although previous studies have attempted to explain this observation, none provided a definitive answer.

Qinghua Ding, a researcher at the University of California, and colleagues propose a new mechanism to explain the anomaly, based on data from observations and modelling experiments. They link the mass-gain event to sea surface temperature anomalies in the tropical Pacific. Between 2021 and 2023, the ocean region extending from the western Pacific to the eastern Indian Ocean – known as the tropical warm pool, where surface temperatures regularly exceed 28°C – experienced unusually persistent warming compared with the previous two decades. According to the study, this tropical warming can be directly linked to the extreme snowfall events observed in Antarctica, which slowed ice mass loss between 2021 and 2023.

The authors showed that the warming of the tropical ocean excited an atmospheric Rossby-wave train – a sequence of alternating high- and low-pressure atmospheric patterns. This process ultimately led to the formation of a high-pressure anomaly over East Antarctica. Combined with moisture transported from subtropical regions and local topographic conditions, this resulted in increased precipitation in the form of snowfall, thereby increasing the mass of the ice sheet. Analysis of ice cores from East Antarctica and climate-model simulations suggests that this phenomenon, which links climate variations between two distant regions, may occur approximately once a decade. The increase in ice-sheet mass is therefore likely to be only temporary.

“The significance of the study also lies in the fact that this discovery gives us a better understanding of the atmospheric mechanisms that cause extreme weather events, and this knowledge can be applied not only to Antarctica but also to understanding weather events in Europe. The fingerprints of tropical changes are also evident in climate variability in the Northern Hemisphere through atmospheric dynamics, and we are now working to describe the mechanisms behind European weather extremes more precisely. Research into global climate processes is therefore essential if we are to understand regional climate changes, such as drought-prone summers,” explained Dániel Topál, co-author of the study.

The research was also supported by the János Bolyai Research Scholarship of the Hungarian Academy of Sciences.