The U.S. and China unveiled long-term plans to curb emissions of carbon dioxide and other gases linked to climate change, a surprise move aimed at kick-starting a new round of international climate negotiations and blunting domestic opposition to cuts in both countries. U.S. President Barack Obama and Chinese President Xi Jinping have been coordinating their CO2-emissions plans for months and met to discuss them jointly Wednesday morning in Beijing, senior U.S. officials said in an earlier conference call with reporters. The announcement, likely to influence global greenhouse-gas emissions in coming decades, caught most climate-change experts by surprise, as many observers had expected a softer commitment or a set of industry initiatives with limited impact.