China, the world’s biggest polluter, is expected to announce a national carbon cap-and-trade system set to begin in 2017, U.S. officials told the New York Times on Thursday. President Xi Jinping is slated to announce the pledge Friday during a White House meeting with President Obama as a part of a combined effort to address climate change ahead of the UN’s climate summit in December. China has been experimenting with smaller cap-and-trade markets for several years, and the new system would effectively consolidate them. A cap-and-trade market would allow China to set a total limit on the country’s greenhouse-gas emissions and issue permits to companies to pollute up to that capacity. Xi’s commitment will include a pledge to create price incentives for generating power from low-carbon sources and restrict public financing of high-carbon infrastructure projects.