Global warming a threat to polar bears? Judge orders review of US rule.

A US district court judge in Washington on Monday rejected arguments from environmental groups that the US Department of Interior was failing to protect polar bears because of its refusal to consider greenhouse gases as one of the threats facing the bears.  The environmentalists had hoped that a ruling in their favor would force the government to regulate greenhouse-gas emissions in order to comply with theEndangered Species Act (ESA). Most scientists agree that greenhouse-gas emissions are causing global warming, and that the rising temperatures are leading to the disappearance of Arctic Ocean ice, which is crucial to the health of polar bear populations. Overall, the ruling highlights the challenge conservation groups can face as they turn to federal regulators to curb greenhouse-gas emissions.