Base question: "What can we do about it?"
One reader tweeted suggesting that scientists build artificial islands to replace the vanishing ice. Another emailed asking why we don't install floating platforms for them at sea.
"Is there no alternative to having them drown from exhaustion?" she wrote.
Andrew Derocher, the University of Alberta biologist who co-authored the original study, applauds that concern. There are some things we can do to help bears that are seeing their habitat vanish, he said — but building fake islands or floating platforms isn't one of them.
For one thing, the scale of such a project is way beyond our abilities.
"If we were to look at the average area that a single polar bear covers in a year, that's already about half the area of Texas," he said.
The Beaufort Sea, where most of the bears Derocher studied live, is home to hundreds of bears and spans thousands of miles. Since it's not a good idea for them to be sharing platforms — an adult male who found himself in the same spot as a mother and her cubs would likely kill the little ones — there would need to be enough platforms for each bear to have several to itself across that incredibly wide range. And if you wanted the platforms to stay in the right place to ensure a polar-bear-friendly distribution, you'd have to anchor them to the ocean floor, which can be more than a mile below the surface.
What's more, even if the platforms proved useful in the summer (when the Beaufort Sea is ice-free for an increasing number of days each year) they would inevitably be crushed when the ice returned in the winter.
But sea ice is not only a resting spot for bears; it's an essential part of their habitat. It supports a whole ecosystem of ice-dependent creatures, including the ring seals that serve as polar bears' main prey. Replacing ice with a platform isn't like taking away someone's bed and substituting an uncomfortable metal pallet. It's more like digging a huge hole on their farm and paving over it with concrete.
"You can still live there, but it won’t be the ecosystem you used to have," Derocher said.
The reality is that the Beaufort Sea probably won't be a polar bear habitat for much longer. Scientists predict that sea ice will retreat farther and farther north as the Earth continues to heat up. Some day, this part of the Arctic will spend the entire summer entirely ice free. Even if we had the technology and resources to build platforms, they could only ever be a stopgap measure to help polar bears in a changing landscape. Eventually, those bears have to find a way to hunt from land instead — otherwise, they'll die out.
But scientists aren't completely helpless. There are a few things they can do to ease the transition.
"The easiest thing is to actually feed bears," Derocher said.
This might seem counterintuitive to anyone who has ever heard the phrase "a fed bear is a dead bear." Getting bears — or any other wild creature — to associate humans with food is almost always bad for their long-term survival. It makes them more likely to attack people (and almost certainly be killed as a result). Even if they stay away from human settlements, they become less able to fend for themselves the longer they're dependent on human intervention. You don't want to create a generation of polar bears that think human scientists are the best source of food.
But scientists can intervene in inconspicuous ways to ensure that creatures have something to eat when their food sources vanish. For example, the Fish and Wildlife Service encourages hunters to leave out carcasses for critically endangered California condors, which eat carrion.
Derocher said that polar bear researchers can go out in a helicopter and drop bear chow from above.
Scientists could also rehabilitate bears that look close to the brink, the same way that we already take in starving seals and otters that wash up on shore. But there are some cultural and practical obstacles to this plan, he noted. Most people, including biologists, are skeptical about rescuing bears, even though we do it for plenty of other species. And even if polar bear researchers could get support for such a program, "where would we put them?" Derocher asked.
"It's one thing to have a cute little sea otter" at a marine research facility, he said. "It's another thing to have 30 or 40 starving polar bears."
The best long-term solution is to move polar bears farther north, to spots that aren't seeing the same level of sea ice loss. This, too, poses problems — mainly, biologists worry about inadvertently transporting diseases and parasites to a population that hasn't been exposed to them before. But on a long list of bad options, it may be the best one.
More news from the Arctic: