Every fall, thousands of polar bears gather on the southwest banks of Hudson Bay, in Canada, to wait for sea ice to form so they can hunt. In Hudson Bay, the ice melts completely during the summer, and re-forms in October or November. But due to climate change, the ice is forming later and melting earlier each year, threatening the existence of these iconic, majestic animals. "Studies suggest they're losing nearly 2 lbs. [1 kilogram] a day while on land," said Steven Amstrup, chief scientist for the conservation group Polar Bears International, "and they arenât dieting intentionally."