COPENHAGEN - China led calls by developing nations on Tuesday for deeper emissions cuts from the United States, Japan and Europe at U.N. climate talks on Tuesday, as a study showed that this decade will be the warmest on record.

Talks drawing 15,000 participants to the talks in Denmark are meant to seal the outline of a climate pact to combat rising seas, desertification, floods and cyclones that could devastate economies and ruin the livelihoods of millions of people.

The first decade of this century was the hottest since records began, the World Meteorological Organisation said on Tuesday, underscoring the threat scientists say the planet faces from rising temperatures.

Yvo de Boer, head of the U.N. Climate Change Secretariat, said the Dec 7-18 talks were off to a good start.

But a rich-poor rift continued to cloud negotiations on finance and emissions cuts. Recession-hit rich countries have not yet made concrete offers to aid developing nations who also want the industrialised world to act faster to curb emissions.

China, the world's biggest emitter of greenhouse gases, criticised goals set by the United States, the European Union and Japan for cuts in greenhouse gas emissions by 2020.

Su Wei, a senior Chinese climate official, said average goals fell short of cuts in emissions of between 25 and 40 percent below 1990 levels by 2020 outlined by the U.N. panel of climate scientists to avoid the worst of global warming.

He said a U.S. offer, totalling 3 percent below 1990 levels by 2020, cannot be regarded as remarkable or notable. An EU cut of 20 percent was not enough, he said, and Japan was setting impossible conditions on its offer of a 25 percent cut by 2020.

Brazil's climate change ambassador said his country did not want to sign up for a long-term goal of halving global emissions by 2050 unless rich nations took on firm shorter-term targets -- which the Danish hosts view as a core outcome for the talks.

The 50 percent cut by 2050 makes no sense unless you have a mid-term target (for rich nations). With a mid-term target it can be a reasonable figure, Sergio Serra told Reuters.

PLEASING THE RICH

A draft 9-page Danish text with annexes seen by Reuters last week continued to draw criticism by poorer nations, who said it undermined the U.N. by side-stepping the world body's role in driving the negotiations.

Focus on the Danish text right now is a distraction from the negotiations, said Kim Carstensen, head of conservation group WWF's global climate initiative.

The behind-the-scenes negotiations tactics under the Danish Presidency have been focusing on pleasing the rich and powerful countries rather than serving the majority of states who are demanding a fair and ambitious solution, he added.

Much is riding on what U.S. Barack Obama can bring to the table in Copenhagen.

Washington's provisional offer is to cut emissions by 17 percent by 2020 from 2005 levels, which works out at just 3 percent below the U.N.'s 1990 baseline.

The U.S. Environmental Protection Agency ruled on Monday that greenhouse gases endanger human health, allowing it to regulate them without legislation from the Senate, where a bill to cut U.S. emissions by 2020 is stalled.

Copenhagen is meant to deliver at least a politically binding agreement that leaders will sign up to. The Danish government has said this would be 5 to 8 pages with annexes from all countries describing pledged actions.

Delegates cautiously welcomed the step as a boost for Obama, who will be joining more than 100 world leaders at the end of the talks during a high-level summit on Dec 17-18.

Indonesia said on Tuesday it was also likely introduce a carbon tax on polluting industries before the government's tenure ends in 2014. (Additional reporting by Gerard Wynn, Alister Doyle and Richard Cowan in Copenhagen and Chris Buckley in Beijing; Writing by David Fogarty; Editing by Dominic Evans)

Japan China Climate change Global warming