Although pictured as being observed in the arctic, this polar bear is at this writing an inhabitant of the Philadelphia Zoo. Obviously a bit of license was taken with the environment. But that is the advantage of art vs. the mechanical processes.
Polar bears, ursus maritimus (Latin for sea bear), are descended from the brown bear and have evolved to where they are adapted to life on the northern ice packs and floes. The bear's skin color is - surprisingly - black, and their hair strands are hollow and so provide extra protection against the cold. There is no pigment in a polar bear's hair and it's the scattering of light that produces the white color (so the debate of whether the fur is white or clear is pointless, depending solely on how you wish to define the concept of color). Some bears acquire colored tints, usually yellow, from diet and environment. There was a case of a green bear at the San Diego Zoo when algae grew in its hollow hair shafts. The algae was removed by a salt solution and the bear was fine, thank you.