Fifteen senators signed a letter telling United Nations climate chief Yvo de Boer to take heart because of recent congressional action to combat global climate change.

De Boer is in Bali, Indonesia, with thousands of delegates from 190 countries trying to iron out a follow-up to the Kyoto Protocol. That pact expires in 2012. Signers from 36 industrial nations are required to curb carbon dioxide and five other gases blamed for global warming by roughly 5 percent below 1990 levels in the next five years.

"We feel that forestalling catastrophic global climate change requires the United States to begin emerging now as a leading participant in the post 2012 international effort to reduce global warming pollution worldwide," reads a section of the Dec. 10 letter signed by 13 Democrats and two Independents. "Fortunately, we can report to you and the conference delegates in Bali that the federal government in Washington is finally moving forward on global warming policy."

The letter signed by Senate Majority Leader Harry Reid of Nevada and Sen. Barbara Boxer of California highlights the Dec. 5 vote to advance a cap-and-trade climate change bill to the Senate floor. The Senate Environment and Public Works Committee, chaired by Boxer, approved the measure authored by Sens. John Warner, R-Va., and Joseph Lieberman, I-Conn.

Though letter-signer John Kerry, D-Mass., made a whirlwind trip to Bali, most of his cohorts remained on U.S. soil tending to a rush of pre-winter recess Capitol Hill legislation.

"The building momentum for strong, effective action on global warming is also supported by progress in the United States outside the federal government," the letter continues. "From coast to coast, U.S. cities, states and counties are adopting aggressive goals and plans for dealing with their own greenhouse emissions. Coalitions of America´s largest corporations are calling for mandatory cuts and a program to put a market price on carbon emissions. And diverse constituencies from municipal officials to public health experts to religious leaders are calling on the federal government to act now."

Australia signed Kyoto in early December, leaving the United States as the only major industrialized nation that has not. And reports thus far from Bali indicate that is unlikely to change soon.

Canada and Japan have joined the United States in its wariness of specific figures drawn up in a preliminary "roadmap." Those numbers call for industrialized nations to cut overall emissions 25 percent to 40 percent by 2020. President Bush has long rejected specific targets, instead maintaining that voluntary action is preferable.

"As the clock ticks down on the Bush administration, it is clear that the Congress believes strongly in acting to establish a mandatory cap-and-trade system to reduce our emissions," Boxer wrote in a separate statement. "I urge the delegates in Bali to be bold and strong."