President Barack Obama said the United States, China and several other countries reached an "unprecedented breakthrough" Friday to curb greenhouse gas emissions - including a mechanism to verify compliance - after a frenzied day of diplomacy at the U.N. climate talks. The agreement, which also includes the developing nations of India, South Africa and Brazil, requires each country to list the actions they will take to cut global warming pollution by specific amounts, a senior Obama administration official said. The official described the deal on the condition of anonymity because specific details had not been announced. Under the agreement, the...