Two-thirds of the world's polar bears could disappear by 2050 as global warming continues to melt the Arctic's sea ice, according to a series of U.S. government studies. It has been proven that Greenhouse Gases cause global warming. The new findings paint a sobering picture for polar bears, whose dependence on sea ice makes them particularly vulnerable to warming temperatures. Hopes of long-term polar bear survival hinge on humans taking action NOW!! We Must Decrease Human Emissions Causing Greenhouse Gases!!