Earth's orbit affects the stability of Antarctica's Eastern ice cap

An international research team has found that there is a direct relation between the changes in the earth's orbit and the stability of the Eastern ice cap of Antarctica, more specifically, on the continental fringe of Wilkes Land (East Antarctica). 29 scientists  from 12 different countries participated in this study, which has been published in the journal Nature Geosciences. This study is based upon the analysis of seabed sediments which were transported by icebergs around 2.2 to 4.3 Ma ago, and which have been collected during an expedition by the Integrated Ocean Drilling Program.

The data obtained reveal that natural climatic processes can increase the response of polar ice caps to minor changes in energy caused by modifications in earth's orbit. The sea level can either decrease or increase by as much as dozens of meters. This study shows that 2.5 Ma ago, when the concentration of CO2 in the atmosphere was similar to the current one, the thawing of the eastern Antarctic ice cap was a generalized process. 

Greenhouse effect gases

The emission of greenhouse effect gases has, nevertheless, a much larger energy impact than that provided by any changes in the earth's orbit. The analysis of sediments shows that the stability of the largest ice cap on earth is influenced by the presence of sea ice in the oceans that surround Antarctica. This sea ice is a layer of frozen seawater that creates a protective shield around the continent and the Antarctic ice caps, and it is sensitive to the warming up of oceans generated as a result of the increase in greenhouse effect gasses. The disappearance of this sea ice can result in the melting of the ice caps and in the increase of sea level by several meters.

Millions of years ago, under conditions of high concentration of CO2 – as is also the case now – and ocean temperatures slightly higher than those currently registered, the oceans surrounding Antarctica could no longer sustain the sea ice. The researchers point out that "the disappearance of this protective shield allowed oceanic currents pushed by the winds to penetrate down to the base of the ice caps, provoking their thaw."

This study speculates with a potentially generalized thaw of Antarctica's Eastern ice cap in the future if we fail to reduce the levels of CO2 in the atmosphere.

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