Slowing of Antarctic Ice Loss Likely Not a New Trend

The Totten Ice Shelf during a Japanese Antarctic research expedition in 2019. (Photo by Yoshihiro Nakayama)

"A pause in Antarctic ice loss does not mean that the ice sheet has stabilized," said Yoshihiro Nakayama, assistant professor of engineering at Dartmouth and a co-author of the study. "During periods of extensive atmospheric river activity, ocean conditions over the continental shelf off Totten Glacier also coincided with warmer periods. Understanding how these atmospheric, oceanic, and cryospheric processes interact—and how this coupled system responds to changing conditions—is an important next step for research."

Between 2021 and 2023, East Antarctica experienced an increase in ice sheet mass that outweighed losses in West Antarctica, leading to a slowdown in the rate of total ice mass loss. Although previous studies have attempted to explain this observation, none has been conclusive.

Nakayama and his co-authors from the Chinese Academy of Sciences, UC Santa Barbara, and the University of Alaska Fairbanks, used data from both observational and model experiments to propose a new mechanism for this anomaly. Changes in the mass of Antarctic ice sheets can be influenced by numerous factors, including sea temperature rises hundreds of miles away in the subtropical ocean. The study links this mass-gain event to surface temperature anomalies in the tropical warm pool, a region of ocean between the western Pacific and eastern Indian Ocean in which surface temperatures regularly exceed 28°C. This area was shown to have experienced unusually persistent warming between 2021 and 2023 in comparison to the previous two decades. 

The authors propose that this warming induced a series of alternating high- and low-pressure weather patterns that eventually led to the formation of a high-pressure anomaly over East Antarctica, resulting in increased precipitation and driving ice sheet mass gain. Analysis of ice cores from the East Antarctic region suggest that this climate event, connecting changes in climate between two distant locations, may occur approximately once every ten years, meaning that any ice sheet mass gain is likely to be temporary.