A team of researchers from the University of Cambridge and the British Antarctic Survey have discovered evidence that a polynya, or area of open water surrounded by sea ice, existed in the Weddell Sea during the last Ice Age. This polynya, which was located near the Larsen C Ice Shelf, would have provided a refuge for marine life during a time when much of the ocean was covered in ice. The findings are published in the journal Nature Communications.

The researchers analyzed sediment cores collected from the seafloor near the Larsen C Ice Shelf. These cores contained layers of diatoms, which are microscopic algae that live in open water. The presence of these diatoms indicates that there was a polynya in the area during the last Ice Age.

The researchers estimate that the polynya was about 100 kilometers wide and 200 kilometers long. It would have been a relatively stable feature, lasting for several thousand years. The polynya would have provided a habitat for a variety of marine life, including seals, whales, and penguins.

The discovery of this polynya has implications for our understanding of the past and future of the Antarctic ice sheet. The researchers believe that the polynya may have helped to prevent the ice sheet from growing too large during the last Ice Age. If this is the case, then the polynya could play a similar role in the future, helping to mitigate the effects of climate change.

This research is a reminder that the Antarctic ice sheet is not a static feature. It is constantly changing, and it is important to understand these changes in order to predict how the ice sheet will respond to climate change in the future.