An ice-free corridor has prolonged Arctic marine life during the last ice age

Norwegian and British scientists have shown that 20,000 years ago, Arctic sea ice covered more than twice the size of winter. Yet there was a small ice-free oasis between the ice-covered continents and the frozen ocean. There, marine life prevailed.

"When we were looking for evidence of biological life in the sediments at the bottom of the ocean, we found that between the oceans covered with sea ice and the terrestrial ice caps, there must be a narrow corridor without ice Jochen Knies A researcher at the Center for Arctic Gas says that these ice-free regions are often referred to as "polynyas", a Russian term for an area of ​​open water surrounded by sea ice and / or ice caps. the Arctic University of Norway and the Geological Survey of Norway.

The new results, recently published in Nature Communications, also reveal that the polynya has been maintained for at least 5,000 years, when the surroundings were largely ice-covered and the global ocean circulation was minimal.

Today, polynyas are common in Antarctica and Greenland. They are formed through a combination of offshore winds blowing nearby ice caps and hot water coming out of the deep ocean. In areas of extreme cold and limited access to food, polynyas are an oasis for the survival of marine mammals and are also essential to the global circulation of the oceans.

"Polynyas in the polar regions are common today, but it is difficult to confirm their existence in the past, but finding chemical fossils of algae living on the high seas and in the ice, we have shown that polynyas last glaciation, "says co-author Simon Belt, professor of chemistry at the University of Plymouth.

During a subsequent period of brutal climate change about 17,500 years ago, fresh water from the melting ice caps covered the entire northern oceans with a thick layer of ice and the polynya has disappeared. This has resulted in a dramatic decline in marine life. It took up to 2000 years for life to resume.

The research is of international importance because it shows the vulnerability of northern oceans' marine ecosystems to periods of rapid climate change, as well as their ability to adapt to various extreme weather conditions.

###