A U.N. climate conference has opened with warnings that the global financial crisis must not divert efforts to reach a new treaty on controlling greenhouse gas emissions.

The prime ministers of Poland and Denmark have told some 10,000 delegates that the financial crisis will pass, but global warming will only get worse.

Yvo de Boer, the U.N.'s top climate official, has also insisted that a treaty to replace the Kyoto Protocol must be ready in just one year.

He said at Monday's opening session that the clock is ticking and the negotiations must shift to a higher gear.

The top U.N. climate scientist, Rajendra Pachauri, reminded delegates of the disasters that await failure: rising sea levels, greater water scarcity and the extinction of species.