"I'm sorry the United States has not ratified the Kyoto Protocol," Gorbachev said, referring to the international accord to reduce emissions of gases that contribute to global warming.

"But I see that the US position is changing, that the US is making serious proposals that will be important in the future," he told Reuters through a translator.

"But we have lost and we are still losing time," said the 76-year-old Gorbachev, who served as the last leader of the Soviet Union from 1985 until its collapse in 1991. He heads environmental group Green Cross International and was in town for its international general assembly.

"We are facing a conflict between men and the rest of nature. We have come to a red line in that conflict," he later told reporters.

The Bush administration, which refused to join in the Kyoto Protocol, has been skeptical about the effect of human activity on global warming, but recently hosted an international meeting about it.

President George W. Bush called for a long-term goal to reduce warming, but did not endorse mandatory limits on greenhouse gas emissions.

A branch of Green Cross -- Global Green USA -- has been working on projects to rebuild New Orleans in an environmentally friendly way. Actor Brad Pitt, who has a house in New Orleans' French Quarter, has been involved in some of the work.

Green Cross, founded by Gorbachev in 1992, held its assembly in New Orleans to highlight the city's needs and the "green" possibilities there.

"It took just a couple of weeks to find billions of dollars -- hundreds of billions of dollars -- to fight the war," Gorbachev said, apparently referring to US-led wars in Iraq and Afghanistan.