San Diego polar bears have surprise snow day –video

San Diego Zoo's three polar bears, Kalluk, Tatqiq and Chinook, have fun in 26 tons of snow, specially prepared for them to enjoy. San Diego is having a mild December and is unlikely to see snow and senior keeper at the zoo, Susan Purtell, says the bears are making the most of their new surroundings. Polar bears are classed a vulnerable species and are threatened by climate change. The current population stands between 20,000 and 25,000

• Visit the zoo's website for more information on it polar bear conservation work