Tag Archives: Lentfer

Same amount of sea ice for Hudson Bay polar bears as 2013, bears still on the ice

Sea ice coverage for Hudson Bay on 14 June converged on levels recorded in 2013, when breakup was slightly later than the average of the last two decades.


There is also more ice over Hudson Bay than there was in 2011, which was an early breakup year (charts for other Arctic regions here, originals here).

Andrew Derocher notes (via twitter) that rather than heading to shore, most of the Hudson Bay bears with satellite tracking collars (7/10) are out on the ice (Fig. 1 below). They appear to be hunting along the ice edge, where they are most likely to find seals.

Update 17 June 2015: Sea ice images for the week 18 June 2015 compared to other years added below, for Hudson Bay and the Beaufort Sea.

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Polar bear-sea ice relationships: what biologists knew in ’72

1972 – a bit over 40 years ago. Seven years before we had reliable sea ice extent data from satellites and the year before the international agreement was signed by Arctic nations to protect polar bears from overhunting.

In 1972, a bear biologist by the name of Jack Lentfer was working for the Alaska Department of Fish and Game, stationed at the Naval Arctic Research Lab in Barrow. Lentfer was one of the founding delegates of the Polar Bear Specialist Group, where he represented US interests until 1981.

In the proceedings of the 1972 PBSG meeting (Lentfer 1972a), Lentfer stated the following in his report to the group:

“Long term warming and cooling trends occur in the Arctic and probably affect polar bear distribution and numbers. Climatic trends should be considered when assessing bear distributions and population data on a long term basis.” [my bold]

Warming and cooling, not just warming.

He also had a paper published that year (Lentfer 1972b), entitled “Polar bear: Sea ice relationships.” Forty years on, I thought it was worth having a look at what Lentfer told his fellow polar bear biologist colleagues back then. Continue reading