(Bloomberg) -- China must move more swiftly to pare greenhouse gas emissions and turn away from coal-fired power to help the world stave off the worst consequences of global warming, the top U.S. climate diplomat said Wednesday.

“We hope China can begin to reduce at some point sooner,” said John Kerry, the U.S. special presidential envoy for climate, in an interview to be aired on Bloomberg TV. “We hope China can begin to reduce at some point sooner, because it is producing now about 28% of all the world’s emissions.”

China -- the world’s No. 1 emitter of greenhouse gases, followed by the U.S. -- on Tuesday promised to stop building new coal-fired power plans outside the country. The announcement by President Xi Jinping could spur a sharp reduction in the construction of new coal plants in developing nations, as China is the largest source of financing for the projects. However, it was unclear if Xi’s pronouncement meant China would cut off all financing for coal-fired power plants, and the country stopped short of ordering a halt to building them within its own borders.

Kerry, in an interview for “Balance of Power With David Westin” to be aired Wednesday, said he has been discussing mutual efforts by the U.S. and China to limit the use of coal-fired power. “It would be great if we could do that,” Kerry said. “We’ve certainly talked about it over the last eight months.”

“Hopefully, President Xi will feel this is a way for the U.S. and China to get on a collaborative track that begins to open possibilities to do the other things we also need to focus on,” Kerry said. 

China is still in the process of developing an official road map to zero out emissions. The nation’s plan for the next five years aims to reduce carbon emissions per unit of gross domestic product by 18% through 2025 and cut energy use per unit of GDP by 13.5%.

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