The polar bear (Ursus maritimus) is a carnivorous bear whose native range lies largely within the Arctic Circle, encompassing the Arctic Ocean, its surrounding seas and surrounding land masses. It is a large bear, approximately the same size as the omnivorous Kodiak bear(Ursus arctos middendorffi). A boar (adult male) weighs around 350–700 kg (772–1,543 lb), while a sow (adult female) is about half that size. Although it is the sister species of the brown bear, it has evolved to occupy a narrower ecological niche, with many body characteristics adapted for cold temperatures, for moving across snow, ice and open water, and for hunting seals, which make up most of its diet. Although most polar bears are born on land, they spend most of their time on the sea ice. Their scientific name means "maritime bear" and derives from this fact. Polar bears hunt their preferred food of seals from the edge of sea ice, often living off fat reserves when no sea ice is present. Because of their dependence on the sea ice, polar bears are classified as marine mammals.

Because of expected habitat loss caused by climate change, the polar bear is classified as a vulnerable species, and at least three of the nineteen polar bear subpopulations are currently in decline.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

This is a video of a starving polar bear, a few hours before its death. Notice that there is no ice in the surrounding. This is the impact of climate change. 

 

 

北极熊发生了什么事？

 

北极熊（Ursus maritimus）是一种食肉熊，其本土范围主要在北极圈内，包括北冰洋，其周围的海洋和周围的陆地。它是一只大熊，与杂食科迪亚克熊（Ursus arctos middendorffi）尺寸大致相同。一头公猪（成年男性）重约350-700公斤（772-1,543磅），而母猪（成年女性）约为其一半的大小。虽然它是棕熊的姊妹品种，但它已经演变成占据更窄的生态位，具有适应寒冷气候的许多身体特征，穿越雪，冰和开阔水域，以及狩猎海豹，它们构成了大部分它的饮食。虽然大多数北极熊都是陆地上出生的，但他们大部分时间都花在海冰上。他们的科学名字就是“海洋熊”，并由此得出结论。北极熊从海冰的边缘捕获他们喜欢的海豹食物，当没有海冰存在时，它们通常靠脂肪储备。由于它们依赖海冰，北极熊被归类为海洋哺乳动物。 由于预期的气候变化造成的栖息地丧失，北极熊属于弱势物种，十九个北极熊亚种中至少有三个正在减少。