A giant hole the size of Maine or Lake Superior has suddenly appeared on the surface of Antarctica and scientists are not quite sure how it came into being. “It looks like you just punched a hole in the ice,” said atmospheric physicist Kent Moore, a professor at the University of Toronto’s Mississauga campus. The sudden emergence of this hole, for the second year in a row, has confounded scientists, whose access to the site is limited. “This is hundreds of kilometers from the ice edge,” said Moore. “If we didn’t have a satellite, we wouldn’t know it was there.”
Known as a polynia, the observed phenomenon occurs when open ocean water is surrounded by solid sea ice, leading to changes in the surrounding ice and below. This particular polynia has been known to scientists since the 1970s, though they were unable to fully investigate in the past. “At that time, the scientific community had just launched the first satellites that provided images of the sea-ice cover from space,” said Dr. Torge Martin, meteorologist and climate modeler. “On-site measurements in the Southern Ocean still require enormous efforts, so they are quite limited.”
This is the second year in a row in which the reported polynia hole has opened in Antarctica, “the second year in a row it’s opened after 40 years of not being there,” according to Moore. While some may feel that climate change is behind this unusual occurrence, Moore cautions further study before drawing any conclusions. However, climate change certainly can influence the structure of sea ice and polynia. “Once the sea ice melts back, you have this huge temperature contrast between the ocean and the atmosphere,” said Moore explained. “It can start driving convection.” This can result in polynias, fueled by warmer water rising to the surface, lasting longer than previously observed.
Regardless of its origins, the reported polynia offers additional information for the study of climate. “For us, this ice-free area is an important new data point which we can use to validate our climate models,” said Moore. “Its occurrence after several decades also confirms our previous calculations.”