While climate change is drastically impacting polar bears' habitats by shrinking the Arctic ice they call home, Scientific American reports some of the bears are being forced to change their diets, resulting in lower mercury consumption. Mercury is toxic to the bears, and can impair neurological development if consumed at high levels.
Melissa McKinney, an ecotoxicologist at the University of Connecticut, conducted a study of the Southern Beaufort Sea polar bear subpopulation. Studying hair samples from 2004 to 2011, McKinney saw "a 65% drop in the bears' mercury levels."
Good news/Bad news: McKinney said while the "bad news is that the bears are losing vital habitat," the good news is that bears being forced to change their diets "have lower levels of toxic mercury."
Go deeper: Because of the shrinking ice, bears are unable to hunt their normal prey: seals. By being forced on land, they have had to find food elsewhere. Some have gravitated toward eating bowhead whale carcasses that have been picked apart and discarded by hunters. McKinney explains in her study that only 20% of the bears are feeding on these carcasses, leaving 80% of the population to fast until the freezing season when they can hunt more successfully. If the other 80% of the bears start feeding on the whale carcasses as well, "the subsidies may not be sufficient for the number of individuals making use of them."