1 thought on “Polar Bears Survived the Ice Free Arctic”

1. “Polar Bears Survived the Ice Free Arctic” (WUWT,July15,2010)

   LONGER SUMMERS……….This sea ice melt-back situation is already occurring in the southerly Western Hudson Bay polar bear population. This is a problem that is measured in terms of weeks. Seal hunting time on the sea ice is reduced by the later freeze-up, and earlier melting. Andrew Derocher is interviewed here.

   http://e360.yale.edu/content/feature.msp?id=2293

   STEVE’S UPDATE……….Wait for it…for the internal quote that contradicts the conclusion Steve draws from his own reference: “The warm period of the Eemian might have come at a time when the polar bear WASN’T SUCH AN ICE SPECIALIST…” (emphasis added)

   THE OPPOSING PRESS RELEASE………. “…The fact that our ancient polar bear lies almost directly at the splitting point between this unique group of brown bears and polar bears, that is, close to their most recent common ancestor of the two species, was very intriguing…”

   While their data demonstrate how adaptive polar bears have been historically, the scientists caution against assuming that the the polar bears, therefore, also will be able to adapt to current and future changes in the Arctic.

   “We have found that polar bears actually survived the interglacial warming period, which was generally warmer than the current one,” Lindqvist says, “but it’s possible that Svalbard might have served as a refugium for bears, providing them with a habitat where they could survive. However, climate change now may be occurring at such an accelerated pace that we do not know if polar bears will be able to keep up.” Ultimately, she notes, the polar bear species may prove less adaptive. “The polar bear may be more evolutionarily constrained because it is today very specialized, morphologically, physiologically, and behaviorally well-adapted to living on the edge of the Arctic ice, subsisting on a few species of seals,” she says. (Penn State Press Release)

   NANOOK OF THE WIKIPEDIA……….Although most polar bears are born on land…(they)…hunt consistently only from sea ice, so spend much of the year on the frozen sea.

   The polar bear tends to frequent areas where sea ice meets water, such as polynas and (temporary) leads, to hunt the seals that make up most of its diet.

   Annual Ice contains areas of water that appear and disappear throughout the year as the weather changes. Seals migrate in response to these changes, and polar bears must follow their prey. In Hudson Bay…(etc)…the ice melts completely each summer…forcing polar bears to go onto land and wait through the months until the next freeze-up. In the Chukchi and Beaufort seas, polar bears retreat each summer to the ice further north that remains frozen year round.

   Most terrestial animals in the Arctic can out run the polar bear on land as polar bears overheat quickly, and most marine animals the bear encounters can outswim it. In some areas the polar bear’s diet is supplemented by walrus calves and by the carcasses of dead adult walruses or whales, whose blubber it readily devours even when rotten.

   With the exception of pregnant females, polar bears are active year round…Unlike brown and black bears, POLAR BEARS ARE CAPABLE OF FASTING FOR UP TO SEVERAL MONTHS during late summer and early autumn when they cannot hunt for seals because the sea is unfrozen. When sea ice is unavailable during summer and early autumn some populations live off fat reserves for months at a time…The polar bear’s biology is specialized to require large amounts of fat from marine mammals, and it CANNOT DERIVE SUFFICIENT CALORIC INTAKE FROM TERRESTIAL FOOD. (emphasis added)

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