BEIJING - China acknowledged Monday that it soon may become the world's biggest source of harmful greenhouse gases but said the United States and other advanced countries must take the lead in fighting global warming because they had been polluting heavily for longer.

Indigenous peoples from the Amazon to Asia said on Wednesday that U.N.-backed clean energy projects meant to combat global warming were aggravating threats to their livelihoods. They said hydropower projects or plantations of fast-growing trees, prompted by a billion-dollar scheme under the U.N.’s Kyoto Protocol for limiting the planet’s dependence on fossil fuels, were damaging nature. “We are not only victims of climate change, we are now victims of the carbon market,” Jocelyn Therese, a spokesman for indigenous peoples of the Amazon basin, told a news conference on the fringes of U.N. talks on global warming. “Efforts that are supposed to…retard climate change are having an equally disastrous effect,” said Ana Pinto, representing indigenous peoples in India.

A U.N. conference working to fix long-term rules to fight global warming beyond 2012 "as soon as possible" was split on Tuesday over whether that meant an accord should be struck in 2008, 2009 or even 2010. Industrial investors, weighing options ranging from coal-fired power plants to wind energy, are frustrated at the possibility of years of uncertainty about rules for fossil fuel emissions upon which carbon markets depend.

European and Asian companies are paying more attention to global warming than their American counterparts. And chemical companies are more focused on the issue than oil companies.