Research into the deep past of western Antarctica strengthens the fragility of melting
A new study on the state of Antarctica’s ice sheets between 18 and 16 million years ago shows that the West Antarctic ice sheet contributed more to sea-level rise events millions of years ago than previously thought.
This period is called the Early Miocene and experienced warm and cold periods. During the warm period, the sea level is thought to have risen by 60 meters-the equivalent of all the ice currently on the Antarctic continent has melted.
However, the contribution of the huge eastern Antarctic ice sheet and the smaller western Antarctic ice sheet to sea level is uncertain.Now, in a paper published in the journal today natureScientists from about 20 institutions have shown that during the colder Miocene period, the western ice sheet was larger than previously thought. It is thought that it was relatively small 10 million years ago, and the sea level rise is thought to be mainly the result of the almost complete melting of the eastern Antarctic ice sheet during the warmest period. However, the ice sheet model conflicts with this idea. They believe that even during the warmest period of the Miocene, when the sea level rose the most, parts of the eastern continent still existed. The new research aligns these models with the geological record of sea level.
Near the edge of the West Antarctic ice sheet. (NASA/Nathan Kurtz)
Lead author Jim Masalek A professor at Imperial College London said: “Our past observations are helpful in predicting the West Antarctic ice sheet, which today is considered particularly vulnerable to the rapid loss of ice, and how it will respond to various future warming scenarios.”
Research team including geochemists Sidney Heming and Benjamin Kesling Columbia University Lamont-Dougherty Earth Observatory, Drilling into the sediments of the Ross Sea in Antarctica. In the core, they retrieved the layers corresponding to the coldest and warmest periods of the Miocene. They found evidence of sedimentary material from the western Antarctic ice sheet toward the sea, indicating that it became quite large during the coldest period.
Researchers say this is possible because in the past, more of the surface under the western ice sheet was higher than sea level, and there was more ice on this part of the continent than today. However, the western Antarctic ice sheet is very corrosive, causing a large amount of land area to fall below sea level. This, in turn, permanently increases the sensitivity of the West Antarctic ice sheet to changing ocean conditions. The study shows that, therefore, as the planet warms, the western Antarctic ice sheet may significantly increase sea levels in the future.
Scientists believe that today’s westerns are very susceptible to the effects of ocean and atmospheric warming. New research supports this idea, showing that it expanded and contracted significantly during the Miocene. The researchers said that now that the geological information is consistent with the model, they can be more confident that the model is capturing past responses from the western Antarctic ice sheet.
Co-author Tina Van der Fleet A professor at Imperial College said: “Although the mass of Antarctica is decreasing at an accelerating rate today, it is estimated that by the end of this century the sea level will rise far less than what we know of geological past when the temperature was 1, 2 or 3. Warm a few degrees. “
She said: “The past is an important window that can tell us what contribution we are making to the earth under a certain degree of warming. The good news is that the large ice sheet is relatively slow to respond to environmental changes, so we may It is still possible to avoid the loss of large ice blocks in many areas. The bad news is that there is a tipping point in the low-lying areas of the ice sheet, and we have not fully understood where this road of no return is.”
The team said that future work requires more detailed study of the fragile low-lying parts of the western and eastern Antarctic ice sheets.
Adapted from a press release from Imperial College London.
