Paris climate accord to take effect; Obama hails 'historic day'

By Alister Doyle and Roberta Rampton OSLO/WASHINGTON (Reuters) - A global agreement to combat climate change will take force after support from European nations sent the accord across an important threshold on Wednesday, prompting U.S. President Barack Obama to hail it as a "historic day" for protecting the planet. European nations raised backing for the 2015 Paris Agreement to countries representing 56.75 percent of world greenhouse gas emissions, above the 55 percent needed for implementation,