A small ice-free oasis between ice covered continents and the frozen ocean allowed marine life to thrive during the last ice age, some 20,000 years ago, new scientific research shows.
“When we were looking for evidence of biological life in sediments at the bottom of the ocean, we found that between the sea ice covered oceans, and the ice sheets on land, there must have been a narrow ice-free corridor that extended over hundreds of kilometers into the Arctic,” said research scientist Jochen Knies, of the Centre for Arctic Gas Hydrate, Environment and Climate at UIT The Arctic University of Norway and Geological Survey of Norway.
“Such ice-free regions are often called ‘polynyas’ – a Russian expression for an area of open water that is surrounded by sea ice and/or ice sheets,” Knies said.
The findings of Knies and Simon Belt, a chemistry professor at Plymouth University in the United Kingdom, were published recently in Nature Communications, an open access journal that publishes research in all areas of the biological, physical, chemical and Earth sciences.
Their research reveals that the polynya was sustained for at least 5,000 years, when Arctic surroundings were largely covered by ice, and global ocean circulation was at a minimum.
“Polynyas in the polar regions are common nowadays, but it’s difficult to confirm their existence in the past,” Belt said. “However, by finding chemical fossils of algae that live in the open ocean and in sea ice, we have shown that polynyas must have existed during the last Ice Age.”
Then during a subsequent period of abrupt climate change some 17,500 years ago, cold freshwater from melting ice caps caused entire northern oceans to be covered by thick sea ice and the polynya disappeared. This resulted in a dramatic decline in marine life, and it took up to 2,000 years for that life to recover.
Their research shows the vulnerability of marine ecosystems in northern oceans to periods of rapid climate change, as well as their adaptability to various extreme climate states, they said.
