After a summer of fasting on land, the bears need to get back to their frozen home to hunt seals and bulk up. But their migration ritual is changing.

The polar vortex hit its peak across much of America on Wednesday, with an icy grip that made Arctic Greenland seem like a toasty vacation spot in comparison. Even Mars has been warmer than North ...

The arctic outbreak that has enveloped the central U.S. is hitting its peak Thursday as frigid temperatures continue to ...