The polar bear is considered a vulnerable species by the International Union for Conservation of Nature (IUCN) with an estimated total population of 22,000 to 31,000 individuals.

Climate change has caused a decline in sea ice, giving the polar bear less access to its favoured prey and increasing the risk of malnutrition and starvation.

[8] Constantine John Phipps formally described the polar bear as a distinct species, Ursus maritimus in 1774, following his 1773 voyage towards the North Pole.

[10][11] However Ursus is widely considered to be the valid genus for the species on the basis of the fossil record and the fact that it can breed with the brown bear.

[10] The largest polar bear on record, reportedly weighing 1,002 kg (2,209 lb), was a male shot at Kotzebue Sound in northwestern Alaska in 1960.

[36] Compared with the brown bear, this species has a more slender build, with a narrower, flatter and smaller skull, a longer neck, and a lower shoulder hump.

[44] The transparent guard hairs forward scatter ultraviolet light between the underfur and the skin, leading to a cycle of absorption and re-emission, keeping them warm.

[62][66] The species tends to frequent areas where sea ice meets water, such as polynyas and leads, to hunt the seals that make up most of its diet.

[84] They will sleep in various positions, including curled up, sitting up, lying on one side, on the back with limbs spread, or on the belly with the rump elevated.

[101] Besides seals, bears will prey on cetacean species such as beluga whales and narwhals, as well as reindeer, birds and their eggs, fish and marine invertebrates.

When a bear spots a seal hauling out on the sea ice, it slowly stalks it with the head and neck lowered, possibly to make its dark nose and eyes less noticeable.

Depending on the area, maternity dens can be found in sea ice just off the coastline or further inland and may be dug underneath snow, earth or a combination of both.

[144] In 2015, the IUCN Red List categorized the polar bear as vulnerable because of a "decline in area of occupancy, extent of occurrence and/or quality of habitat".

[57] A 2008 study predicted two-thirds of the world's polar bears may disappear by 2050, based on the reduction of sea ice, and only one population would likely survive in 50 years.

[147] A 2012 review suggested that polar bears may become regionally extinct in southern areas by 2050 if trends continue, leaving the Canadian Archipelago and northern Greenland as strongholds.

[150] Reduction in sea ice cover also forces bears to swim longer distances, which further depletes their energy stores and occasionally leads to drowning.

The Chukchi Sea Planning Area of northwestern Alaska, which has had many drilling leases, was found to be an important site for non-denning female bears.

[153] Polar bears accumulate high levels of persistent organic pollutants such as polychlorinated biphenyl (PCBs) and chlorinated pesticides, because of their position at the top of the ecological pyramid.

[166] Polar bears were hunted as early as 8,000 years ago, as indicated by archaeological remains at Zhokhov Island in the East Siberian Sea.

[171] Russia traded polar bear products as early as 1556, with Novaya Zemlya and Franz Josef Land being important commercial centres.

[176] Over 50 polar bears swarmed a town in Novaya Zemlya in February 2019, leading local authorities to declare a state of emergency.

[180] The polar bear was for long a particularly sought-after species for exotic animal collectors, since it was relatively rare and remote living and had a reputation as a ferocious beast.

In 1609, James VI and I of Scotland, England and Ireland was given two polar bear cubs by the sailor Jonas Poole, who got them during a trip to Svalbard.

[186] Polar bear exhibits were innovated by Carl Hagenbeck, who replaced cages and pits with settings that mimicked the animal's natural environment.

In 1907, he revealed a complex panoramic structure at the Tierpark Hagenbeck Zoo in Hamburg consisting of exhibits made of artificial snow and ice separated by moats.

Similar naturalistic and "immersive" exhibits were opened in the early 21st century, such as the "Arctic Ring of Life" at the Detroit Zoo and Ontario's Cochrane Polar Bear Habitat.

[191] Several captive polar bears gained celebrity status in the late 20th and early 21st century, notably Knut of the Berlin Zoological Garden, who was rejected by his mother and had to be hand-reared by zookeepers.

[196] In sufficiently warm conditions, algae concentrated in the medulla of their fur's guard hairs may cause zoo polar bears to appear green.

[200] Two Norwegian fairy tales, "East of the Sun and West of the Moon" and "White-Bear-King-Valemon", involve white bears turning into men and seducing women.

[206] To make a statement about global warming, in 2009 a Copenhagen ice statue of a polar bear with a bronze skeleton was purposely left to melt in the sun.