In the spring, during their prime hunting season, polar bears need an insanely large amount of food to stay healthy — over 12,000 kilocalories a day, or roughly 6,000 times what humans need, according to new research. That’s a lot more than what scientists previously thought these predators needed to stay healthy. And that means that, as Arctic ice keeps melting because of rising temperatures, polar bears may be in more trouble than we had anticipated. In April of 2014, 2015, and 2016, researchers tracked nine female polar bears living on the sea ice of the Beaufort Sea, off the...