South Korean President Lee Myung-bak and Chinese Vice President Xi Jinping, meeting for breakfast in Seoul, also studied a four-point proposal to promote trade and agreed to strengthen cooperation on energy saving, environmental protection, telecommunications and finance.
On the nuclear problem, Lee said, "I think next year will be an important juncture in resolving the North Korean nuclear issue. I hope China will play a bigger role."
Lee was quoted by a spokesman as saying that prospects for the global fight against climate change were not as dark as some advanced countries have forecast.
He saw the U.N. summit in Copenhagen, Denmark, as a good starting point to deal with the issue, South Korea's Yonhap News Agency said.