Republicans won control of the Senate for the first time in eight years and expanded their majority in the U.S. House of Representatives. Emboldened, they will also likely move to block funding for the crown jewel of Obama's climate agenda: the Environmental Protection Agency's proposed rules to limit greenhouse gas emissions from power plants.

This looming political shift could slow U.S. efforts to reduce heat-trapping emissions and comes just days after scientists on the United Nations' Intergovernmental Panel on Climate Change urged swift action to slash emissions from the burning of fossil fuels.

"We'll clearly see votes to block a lot of administration initiatives," says David Goldston, director of government affairs at the Natural Resources Defense Council, an environmental