The Polar Bear is designed to survive in one of the harshest climates on earth, depending on the arctic ice for it's survival. The Polar Bear hunts seals by waiting at the seals air holes and snatching them as they come up for air. The disappearance of the ice flows means death to the Polar Bears. The Bears have been seen swimming 100km off shore in search of the ice and seals. They are drowning.
Each year the ice returns to the shore weeks later than previous years. Each week means a week less hunting and 10-15 less kgs of fat, this translates to females having singletons instead of the normal twins or triplets. And the dens in which the mothers raise the young are melting and collapsing killing both the mothers and her cubs.
POP's (Persistent Organic Pollutants) dioxins, furans, lindane, dieldrin, PCP's and DDT all of which have an affinity for fat Top level predators in the Arctic depend on high levels of fat in the diet for insulation. In fact the Polar Bear will often eat only the fat and leave the meat for the Arctic Fox which follow the Polar bear. Fat takes less water to digest then meat and fresh water is at a premium on the ice.
Canada is the only nation that still allows the hunting of Polar Bears by non-natives. By the mid 20th century the Polar Bear hunting finally became regulated. The Polar Bear Specialist Group of the International Union for Conservation of Nature and Natural Resources was formed. In 1973 the five Polar Bear Nations signed the Agreement on the Conservation of Polar Bears.
Exploration and tanker activity means bilge dumping and spills. The oil destroys the Polar Bear furs waterproofing and insulation, resulting in death.