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As temperatures rise due to climate change, the melting of the polar ice caps is accelerating. An international team of researchers led by geologist Dr Kim Jakob of the University of Heidelberg has now taken a closer look at the dynamics of the East Antarctic ice sheet. This is by far the largest mass of ice on Earth and is assumed to be less sensitive to climate change than other ice sheets simply due to its size. The researchers analyzed data they had obtained from deep-sea sediments dating back about 2.5 million years. This allowed them to determine the factors responsible for the stability of the East Antarctic ice sheet. The results indicate that East Antarctica’s ice masses may be far less stable in a consistently warm climate than previously thought.
“The melting of the polar ice caps leads to a rise in global sea level, which is becoming an ever greater threat to coastal areas,” explains Dr. Jakob of the Institute of Earth Sciences of the University of Heidelberg. To better understand past changes in the great ice masses of East Antarctica, his research team performed geochemical analyzes on deep-sea sediments of the Atlantic Ocean. The sediments were obtained through the Integrated Ocean Drilling Program (IODP), an international consortium of scientists formed to explore the ocean floor.
These analyzes allowed the reconstruction of global sea level change from about 2.8 million to 2.4 million years ago, which in turn reflects changes in the total volume of ice. During this period, a high atmospheric CO2 concentrations with values similar to those predicted for the near future have decreased to a level comparable to pre-industrial CO2 content of the atmosphere. The investigation reveals for the first time that the East Antarctic ice sheet achieved an unprecedented increase in stability some 2.5 million years ago compared to the earliest periods in Earth’s history.
The conventionally accepted factors for promoting the growth and decay of the polar ice caps throughout the history of the Earth are the intensity of solar radiation and CO2 content of the atmosphere. However, Dr. Jakob and her team have now discovered an additional factor that played a decisive role in the stabilization of the East Antarctic ice sheet: the formation of large glaciers in the Northern Hemisphere, which caused the level to drop. global sea. This drop in sea level reduced East Antarctic ice exposure to relatively warm ocean waters and thus minimized the potential of seawater to cause basal melt in parts of the ice sheet.
The study results contribute to a better understanding of the dynamics of global ice sheets under high atmospheric CO2 mergers, as planned for the foreseeable future. Further melting of ice masses in the Northern Hemisphere due to anthropogenic climate change and subsequent global sea level rise could contribute to a renewed destabilization of the East Antarctic ice sheet.
In addition to scientists from the University of Heidelberg, researchers from Goethe University in Frankfurt, the Max Planck Institute for Chemistry in Mainz and the University of Southampton (Great Britain) contributed to this study. The research was funded in the context of the German Research Foundation’s IODP priority program. The results were published in the journal Proceedings of the National Academy of Sciences of the United States of America.
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