The East Antarctic Ice Sheet is assumed to be less sensitive to climate change than other ice sheets simply because of its size. But how accurate is this perception? A team of researchers has analysed data to reveal slightly different findings.
As temperatures rise due to climate change, the melting of polar ice sheets is accelerating. An international team of researchers led by geoscientist Dr Kim Jakob from Heidelberg University has examined the dynamics of the East Antarctic Ice Sheet more closely.
The ice sheet is by far the largest ice mass on Earth and is assumed to be less sensitive to climate change than other ice sheets simply because of its size. The researchers analysed data that they had obtained from deep-sea sediments dating back approximately 2.5 million years. The findings indicate that the ice masses of East Antarctica could be much less stable in a constantly warming climate than previously thought, according to a statement.
“The melting of polar ice sheets leads to a rise in global sea level, which is becoming an ever greater threat to coastal areas,” explains Dr Jakob from the Institute of Earth Sciences at Heidelberg University.
Understanding past changes
To better understand past changes in the large ice masses of East Antarctica, Dr Jakob’s research team performed geochemical analyses on deep-sea sediments from 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 analyses enabled the reconstruction of global sea-level change from approximately 2.8 to 2.4 million years ago, which in turn reflects variations in the total volume of ice.
During this period, high atmospheric CO2 concentrations with values similar to those predicted for the near future decreased to a level comparable to the 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 approximately 2.5 million years ago compared to older periods in the Earth’s history.
Factors conventionally accepted to have promoted the growth and decay of polar ice sheets during the Earth’s history are the intensity of solar radiation and the CO2 content of the atmosphere.
However, Dr Jakob and her team have now found an additional factor that played a decisive role in stabilising the East Antarctic Ice Sheet – the formation of large glaciers in the northern hemisphere, which caused global sea level to fall. This sea-level fall reduced the exposure of East Antarctic ice to relatively warm ocean waters and thus minimised the potential of sea water to cause basal melt in parts of the ice sheet, explains the statement.
The findings of the study contribute to a better understanding of the dynamics of global ice sheets under elevated atmospheric CO2 concentrations, as expected for the near future. Further melting of ice masses in the northern hemisphere due to anthropogenic climate change and subsequent rising global sea levels could contribute to a renewed destabilisation of the ice sheet in East Antarctica.
The findings were published in the journal Proceedings of the National Academy of Sciences of the United States of America.