The United States and China have promised to cooperate more closely in combatting climate change.

In a joint statement issued after a visit by U.S. Secretary of State John Kerry, the two governments said Saturday they have agreed on steps to carry out commitments to curb greenhouse gas output. Those include reducing vehicle emissions, improving energy efficiency of buildings and other measures.

China and the United States are the biggest sources of emissions of carbon dioxide and other gases that cause the atmosphere to trap solar heat and alter the climate. Scientists warn such changes will lead to drought and other extreme weather conditions.

The two governments will "contribute significantly to successful 2015 global efforts to meet this challenge," the statement said.