Arctic Sea Ice Melt Threatens Ringed Seal Habitat

The Arctic sea ice is drastically melting over the past few decades, threatening the ecosystem and in particular the ringed seal habitat, researchers from the University of Washington and National Science Foundation have found.

The ringed seal builds caves to rear their young in snow drifts on sea ice. Snow depths must be on average at least 20 centimeters, or eight inches, to enable drifts deep enough to support the caves. But due to global warming, the ice in the Arctic is drastically melting. The platform that allows the snow to pile up disappears, ultimately reducing the area where the seals can raise their pups.

"It's an absolute condition they need," said Cecilia Bitz, an associate professor of atmospheric sciences at the University of Washington.

Scientists analysed data obtained from ten different climate models, looking at historic and future changes of things like sea ice area, precipitation, snowfall and snow depth on sea ice. The data revealed that there has been drastic ice melt across the Arctic region during this century.

Researchers anticipate that the area of the Arctic that accumulates at least 20 centimeters of snow will decrease by almost 70 percent this century. With insufficient snow depth, caves will not hold up.

The research is important for more than just the ringed seals. "There are many other reasons to study snow cover," Hezel said. "It has a huge thermodynamic impact on the thickness of the ice."

Snow present on sea ice in fall and winter acts like a blanket that slows the release of heat from the warm ocean into the atmosphere.

In the spring, snow has a different impact on the ice. Since snow is more reflective than ice, it creates a cooling effect on the surface. "So the presence of snow helps sustain the icepack into spring time," Hezel said.