U.S. Secretary of State Hillary Clinton announced Thursday the formation of a new global coalition aimed at reducing emissions of some short-lived pollutants that contribute to climate change.

Clinton said the Climate and Clean Air Coalition of the United States, Bangladesh, Canada, Mexico, Sweden and Ghana will launch a global drive to curb soot (black carbon), methane and hydrofluorocarbons.

Soot from diesel exhausts and the burning of wood, agricultural waste and dung for heating and cooking causes an estimated two million premature deaths a year, particularly in the poorest countries. Methane comes from natural-gas production, landfills, agriculture and other sources. Hydrofluorocarbons are used in foam and refrigerants.

The chief U.S. diplomat said such pollutants survive only a short time in the atmosphere -- unlike long-lasting carbon dioxide, the main climate change culprit -- but account for more than a third of global warming.

"We know that in the principal effort necessary to reduce the effects of carbon dioxide, the world has not yet done enough," Clinton told an audience at the State Department that included envoys from the coalition countries.

"So when we discover effective and affordable ways to reduce global warming -- not just a little, but by a lot -- it is a call to action for all of us," Clinton said.

The United States intends to contribute 12 million U.S. dollars and Canada three million dollars over two years to get the program off the ground and to help recruit other countries to participate. The United Nations Environment Program will run the project.