Monthly Archives: January 2016

Paleoclimate + genetic study confirms: Arctic species adapted to sea ice changes

A new paper that combines paleoclimatology data for the last 56 million years with molecular genetic evidence concludes there were no biological extinctions [of Arctic marine animals] over the last 1.5M years despite profound Arctic sea ice changes that included ice-free summers: polar bears, seals, walrus and other species successfully adapted to habitat changes that exceeded those predicted by USGS and US Fish and Wildlife polar bear biologists over the next 100 years.

Healy Aug  24 2015 Polar-Bear V Tim Kenna

Cronin, T. M. and Cronin, M.A. 2015. Biological response to climate change in the Arctic Ocean: the view from the past. Arktos 1:1-18 [Open access]

Thomas Cronin is a USGS paleoclimatologist at the Eastern Geology and Paleoclimate Science Center, and Matthew Cronin is a molecular geneticist at the University of Alaska Fairbanks (see previous posts here and here about Matt’s work on the genetics of polar bear evolution).

From the Abstract:

Arctic climatic extremes include 25°C hyperthermal periods during the Paleocene-Eocene (56–46 million years ago, Ma), Quaternary glacial periods when thick ice shelves and sea ice cover rendered the Arctic Ocean nearly uninhabitable, seasonally sea-ice-free interglacials and abrupt climate reversals.

The final discussion and two summary graphics from this paper (copied below) are especially useful:

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Davis Strait polar bear habitat well above average for the first week of winter

The region inhabited by the Davis Strait subpopulation of polar bears dips as far south as James Bay and has a history of highly variable sea ice coverage.

Canadian Arctic Jan 7 2016_CIS

For the last two years Davis Strait sea ice in March has been well above average, while other years it been well below. You might be surprised to hear that 1969 had the lowest February/March ice coverage over the entire the 1969-2002 record (Johnston et al. 2005: 211), which ice charts show now extend to 2015 (see below). Reports of sealers working north of Newfoundland and in the Gulf of St. Lawrence in the first few decades of the 20th century show this variability has likely always been a characteristic of the area (Ryan 2014).

Remarkably, this year’s ice coverage for the first week in January is well above what they were in 2014 and 2015 – even though those two years were above average by March. In fact, there hasn’t been this much polar bear habitat in the Southern Labrador Sea in the first week of January since at least 1993.
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Tracking polar bears in the Beaufort Sea – one tagged bear left at year end 2015

I’ve combined the months of November and December for this post on USGS polar bear tracking in the Beaufort Sea because there’s not much to tell: there’s one tagged bear left and she’s going almost nowhere. Where’s the news in that?

Beaufort tracking USGS bear-movements-November 2015 sm

Movements of 1 satellite-tagged polar bear female for the month of November, 2015; shown with sea ice coverage at 30 November 2015. This bear was tagged in the spring of 2015 in the Southern Beaufort Sea. See original image here and December movements below.

Actually, it does tell us something: this female is probably in a sea ice den, a relative common phenomenon in the Beaufort Sea. And she’s on ice that’s out over very deep water. Continue reading