Polar bears can adapt a bit to the changing Arctic climate, narwhals can't, she said.2. From National Geographic in 2004 here:
While polar bears are "good-looking fluffy white creatures," Laidre said narwhals, which are medium-sized whales, are "not that cute."
The narwhal, which dives about 6,000 feet to feed on Greenland halibut, is the ultimate specialist, evolved specifically to live in small cracks in parts of the Arctic where it's 99 percent heavy ice, Laidre said. As the ice melts, not only is the narwhal habitat changed, predators such as killer whales will likely intrude more often.
In addition, changing sea-ice conditions may be affecting narwhal survival. While warming trends have generally caused sea ice to shrink, it has been increasing over the last several decades in Baffin Bay, one of the narwhal's wintering grounds.3. A related post is here.
"Narwhals aren't usually in trouble when they're migrating, because they're constantly moving ahead of the ice," Laidre said. But the species spends the winter in areas thick with pack ice—often more than 95 percent covered. With increasing sea ice, these close quarters could be getting even closer, and wintering narwhals could become trapped in the ice more often.