Cliché or no, climate change really is coming for the polar bears

Polar bears are the easy target, the global warming victim too cute and obvious to really mean what we want them to mean, right? Look at that guy up at the top; enviros just picked this species as a poster child because they’re amazing and adorable, right? They can’t really be that threatened by rising temperatures and disappearing sea ice. Right?

Well, wrong. The cliché is a cliché for a reason, and new research supports this: By century’s end, business-as-usual emissions and attendant warming will yield between two and five months of ice-free conditions in one polar bear-rich region, the Canadian Arctic Archipelago (CAA). Right now, there are essentially no such conditions, meaning polar bears don’t ever have to deal with an ice-free habitat. A few months of no ice would be catastrophic for warming’s most charismatic megafauna victim.

Previous research has suggested that the CAA and Greenland had the best chance of maintaining polar bear populations through the end of the 21st century, according to researchers writing in the journal PLoS One. They argue, though, that earlier studies haven’t sufficiently modeled the complex geography of the CAA; and this is a big deal for polar bears, as about one quarter of all the polar bears in the world rely on ice in or connected to this region of the world.

The researchers used existing climate and sea ice models, and drilled down to model individual bits of the complicated CAA area. They found that by the late 21st century the southernmost regions of the Archipelago will be entirely ice-free for five months. Even in the far north, in areas like Kane Basin—a strait that is actually to the north of Canada’s northernmost island—our current warming trajectory will yield 2 to 4 months of ice-free waters. “We find that sea ice conditions may become unsupportive of polar bear population persistence in the CAA and its surroundings by the late 21st century,” the authors conclude.

This means polar bears will either run out of ice and drown or starve, or will head south, running into humans and other species alike (the rise of “grolar bears” being a symptom of the latter issue). It also would likely have negative effects on reproductive health of the animals, the researchers wrote. They suggest that conservation efforts should focus on those areas that are slower to experience changes to sea ice—areas like Norwegian Bay and the Queen Elizabeth Islands. That is a practical, if depressing, conclusion: it assumes the more rapidly shifting areas are essentially doomed as polar bear habitats. And they’re probably right about that.

“By 2100 all regions of the study area may cross the critical point-of-no-return, putting the persistence of the CAA polar bear populations in jeopardy,” the authors wrote. At this rate, we’ll soon need a new global warming poster child. – Dave Levitan | December 2 2014

Source: Hamilton SG, Castro de la Guardia L, Derocher AE, et al (2014). Projected polar bear sea ice habitat in the Canadian Arctic Archipelago, PLoS One, 9 (11) e113746. DOI: 10.1371/journal.pone.0113746

Image: Shutterstuck, Vladimir Melnik

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