Polar bear researchers just published a study that suggests polar bears have moved around the Arctic in direct response to recent sea ice changes — a conclusion I suggest you take with a grain of salt and a raised eyebrow.
That’s because they have also proposed, among other things, that the Svalbard Archipelago was a sea ice refugium during warm interglacial periods, and could be again if the Arctic warms as predicted. That they would accept and promote such a model-based conclusion, which has no relationship with reality, calls their scientific judgment into question.
Based on genetic model results, the Svalbard Archipelago (circled) has been proposed as a sea ice refugium for polar bears during previous warm Interglacial periods and during predicted sea ice declines in the future. Yet most years since 1979 (2014 was one exception), this region has been ice free during the summer, making Svalbard a decidedly poor candidate for retaining sea ice when it’s much warmer than today.
Posted in Population, Sea ice habitat
Tagged Canadian Arctic Archipelago, Cronin, DNA, extinction, gene flow, genetics, Hamilton, Miller, models, PBSG, Peacock, polar bear, Polyak, predictions, refugium, sea ice, warming Arctic
Last in a three-part series of my critique of Miller et al.’s (2012)
paper on the newest genetic evidence for the origin of polar bears. Part 1 here, Part 2 here.
Here is my final (I hope) comments on the claims made in that paper, suggesting why we might want to take them with a grain of salt.
These are the points regarding this paper that I think deserve a critical look. In this post, I’ll elaborate on Claims #3 and #4. [I’ve added one more to the original three listed].
Claim #1 Polar bears and brown bears (aka grizzlies) arose 4-5 million years old. [I countered with fossil evidence]
Claim #2 Hybridization in both directions occurred repeatedly throughout the evolutionary history of polar bears and brown bears. [I countered with full details on known hybrids]
Claim #3 Svalbard may have been an important refugium for polar bears during warm interglacial periods – and related sea ice issues related to the origin of polar bears as a species.
Claim #4 Polar bear population numbers (population size estimates) over the last one million years track changes in climate (warmer/colder periods).
Claim #3 Svalbard may have been an important refugium for polar bears during warm interglacial periods (and related sea ice issues related to the origin of polar bears as a species) [Which I’ll counter with evidence on paleo sea ice]