Shrinking snow depth on Arctic sea ice threatens ringed seal habitat

Nancy Gohring in the University of Washington News: As sea ice in the Arctic continues to shrink during this century, more than two thirds of the area with sufficient snow cover for ringed seals to reproduce also will disappear, challenging their survival, scientists report in a new study.

The ringed seal, currently under consideration for threatened species listing, builds caves to rear its young in snow drifts on sea ice. Snow depths must be on average at least 20 centimeters, or 8 inches, to enable drifts deep enough to support the caves.

“It’s an absolute condition they need,” said Cecilia Bitz, an associate professor of atmospheric sciences at the University of Washington. She’s a co-author of the study, published in the journal Geophysical Research Letters.

But without sea ice, the platform that allows the snow to pile up disappears, ultimately reducing the area where the seals can raise their pups.

Bitz typically focuses on studying the area and thickness of sea ice. “But when a seal biologist telephoned and asked what our climate models predict for snow depth on the ice, I said, ‘I have no idea,’” she said. “We had never looked.”

That biologist was co-author Brendan Kelly of the National Science Foundation and he was curious about the snow depth trend because he was contributing to a governmental report in response to the petition to list the seals as threatened.

The researchers, including lead author and UW atmospheric sciences graduate student Paul Hezel, found that snowfall patterns will change during this century but the most important factor in determining snow depth on the ice will be the disappearance of the sea ice....

A ringed seal in its lair, shot by Brendan Kelly, found on the University of Washington website