In response to mounting concern over the potential risks posed by global warming, the Framework Convention on Climate Change was opened for signature in Rio di Janeiro at the United Nations Conference on Environment and Development (also referred to as the "Earth Summit") in June 1992. More than 150 nations, including the United States, signed the treaty, which entered into force less than two years later, on March 21, 1994. It has now been ratified by more than 155 nations.
The U.S. was the fourth nation overall, and the first industrialized nation, to ratify this landmark accord. Under this treaty, the world's industrialized nations pledged to establish policies and measures that reduce emissions of the greenhouse gases that are changing the Earth's climate.
The United States is strongly committed to addressing the challenge of climate change with cost-effective policies that are good both for the environment and the economy. The approach has three pillars. First, to contribute to a necessary foundation in science, the U.S. maintains the most extensive research effort on climate change of any nation in the world. Second, U.S. policies are based on win-win partnerships with the private sector, states, localities, and non-governmental organizations. Finally, the U.S. is committed to strengthening international responses to the risks of climate change – global warming will require global solutions.