GLASGOW—More than 190 nations reached a deal at the United Nations summit here that aims to accelerate greenhouse-gas-emissions cuts across the world, but leaves big questions over how governments will follow through in the coming decade to try to avert the worst effects of global warming.
Supporters say the deal—struck Saturday evening after two weeks of negotiations—signals new determination among the world’s governments to shift away from burning fossil fuels, the main source of greenhouse gases that scientists say are causing the earth to warm. The agreement, though, features weaknesses that have hamstrung U.N. climate talks over the decades.