A new study unravels the long-held mystery of climate change in Antarctica

Anna Ruth Halberstadt is conducting field research in the dry valleys of McMurdo in Antarctica. Credit: Anna Ruth Halberstadt

The discrepancy between terrestrial and marine data has been resolved; shows that ice sheets are vulnerable to small fluctuations in CO2.

A new study led by the University of Massachusetts Amherst finally eliminates the long-standing inconsistency of geological data that contradicted studies of marine ice cover behavior with those that reconstructed past conditions on land. A study published recently in the Journal Geologyand funded by the National Science Foundation and the National Council for Environmental Research, adds weight to the evidence that the Antarctic ice sheet is sensitive to small changes in CO2 levels and that in the past much of the ice sheet could disappear below CO2 levels similar today.

Scientists studying the history of the Antarctic Ice Shield have been debated for decades, revolving around the inconsistency of marine data from the Ross Sea and data collected in the dry McMurd Valleys, the ice-cold mountainous coastal region to the Ross Sea. In one corner are marine records from the seabed showing that the Antarctic ice sheet has repeatedly shrunk to a size smaller than it has today over the past 10 million years, and that the ice-covered Dew Sea has periodically been an open ocean. This suggests that the Antarctic ice sheet is sensitive to relatively small fluctuations in CO2 and temperature and retreats in past warm periods.

Halberstadt Analyzing Marine Sediment Cors

Halberstadt analyzes the nuclei of marine sediments. Credit: UMass Amherst

In another corner are terrestrial studies of ancient and well-preserved landforms in the dry McMurd Valleys, which show that cold desert conditions on land persisted for the same ten-millionth period of time, leading some researchers to conclude that the Antarctic glacier is stable the shield has persisted over the past few warm periods and may therefore be less susceptible to global warming than marine data suggest.

Is the West Antarctic Glacier sensitive to global warming or not? Addressing this debate is of planetary importance, as the same parts of the Antarctic ice sheet that collapsed in the past could raise future sea levels by 10 feet or more if they collapse in our time.

Using a series of high-resolution climate models and ice cover models, Anna Ruth Halberstadt, who completed this research as part of her doctoral philosophy. in geological sciences at UMass Amherst, and her colleagues were able to show that in the dry McMurdo valleys it is quite possible the existence of temperatures below zero, even if the neighboring Rosa Sea is completely free of ice. “Now we can say,‘ Okay, now we understand why these two data sets turned out to be contradictory, ’” says Halberstadt, lead author of the article.

Halberstadt and her team conducted a series of experiments using modern models of climate and sea ice to show that the dry McMurdo Valleys could certainly remain frozen even if the ice sheet collapsed. Halberstadt says that “this work has finally brought all the geological information into line, and suggests that much of the Antarctic ice sheet may have collapsed in climatic situations similar to today’s.”

Reference: “Combination of stable subzero temperatures in the dry valleys of McMurdo, Antarctica, with Neogene dynamic oscillations of the sea glacier” Anna Ruth W. Halberstadt, Douglas E. Kovalevsky and Robert M. DeCont, February 11, 2022, Geology.
DOI: 10.1130 / G49664.1 A new study unravels the long-held mystery of climate change in Antarctica

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