WASHINGTON (Reuters) - A controversial climate change bill cleared its first hurdle in the U.S. Senate on Thursday, allowing President Barack Obama to tout progress in the run-up to next month's global warming talks in Copenhagen.

Democrats on the Senate Environment and Public Works Committee ignored a Republican boycott and used their majority to approve the legislation that would require U.S. industry to reduce emissions of carbon dioxide and other greenhouse gases 20 percent by 2020, from 2005 levels.

I think this is a great signal for Copenhagen that there's a will to do what it takes to advance this issue, committee Chairman Barbara Boxer told reporters after her panel voted.

The committee vote also came as international negotiators held a contentious climate change meeting in Barcelona, their final session before the Copenhagen summit starts December 7.

But Democrats are likely to fall far short of their goal of passing legislation in the full Senate before Copenhagen as Boxer's bill lacks enough support for full approval.

Senator John Kerry, who co-authored the committee-approved bill with fellow Democrat Boxer, is leading an effort with some Republicans and the White House to draft a compromise.

With all seven Republicans chairs empty, 11 Democrats voted to approve the bill. Only one Democrat, Senator Max Baucus, who chairs the powerful Senate Finance Committee that also will review climate legislation, voted no.

AREAS OF COMPROMISE

Before casting his vote, Baucus said he was committed to passing a bill to tackle global warming. But he said the goal of cutting carbon emissions from utilities, factories and oil refineries by 20 percent by 2020 was too high.

Instead, Baucus said he would seek a 17 percent goal, with a trigger to hike it up to 20 percent if other countries play by the same rules in cutting their carbon emissions.

A climate bill that narrowly passed the U.S. House of Representatives in June sets a 17 percent target for 2020.

Baucus' vote against the bill reflected the difficulties ahead in crafting a measure that would have to attract the 60 votes needed for passage by the Senate.

Other senators from Midwestern and Southern states heavily reliant on coal will seek their own changes, which could upset liberals now supporting the bill.

There is widespread expectation in the Senate that for any climate control bill to pass, it will have to contain new government incentives for expanding U.S. nuclear power-generating capacity and offshore oil drilling, along with money to help develop clean ways to burn coal, which is in abundant supply in the United States.

Republicans complained that a detailed economic analysis of Boxer's bill had not been done -- a charge Democrats rebutted -- and that any work on the bill should await such analysis.

But Senator James Inhofe, the senior Republican on the committee, seemed to have enough information to conclude: It is time for a different approach, one that grows, rather than shrinks our economy, creates, rather than destroys jobs, and strengthens, rather than weakens our energy security.

There were scores of amendments to Boxer's bill that environment committee members wanted to debate and vote on before approving it, but they were unable to because of the Republican boycott.

Under committee rules, at least two Republicans had to be present to debate and vote on changing the bill.

Boxer delayed work on the legislation for two days, saying she was giving Republicans the opportunity to collect more information from EPA officials and to offer their own amendments.

But Republicans did not take her up on the offer and by Thursday, Boxer had lost patience with the delay.

(Editing by Philip Barbara)

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