Senators Barbara Boxer, Jeff Bingaman and Joseph Lieberman, all set to head key committees on global warming when Democrats take over Congress in January, called on Bush to work with the incoming majority to pass "meaningful" climate change legislation next year.

"The US must move quickly to adopt economy-wide constraints on domestic GHG (greenhouse gas) emissions and then work with the international community to forge an effective and equitable global agreement," the senators said in a letter sent to Bush Wednesday.

Bush has refused to ratify the Kyoto Protocol, saying it would hurt the US economy. Kyoto commits industrialized countries that have signed and ratified it to trim greenhouse gases by 2012, as compared with a 1990 benchmark.

Instead, he has promoted voluntary action, backed by some incentives for cleaner energy sources and gains in energy efficiency.

The senators said the Democratic victory over Bush's Republicans in last week's elections, which ended their 12-year majority in Congress, has "signaled a need to change direction in many areas, including global warming."

"If we are to leave our children a world that resembles the earth we inherited, we must act now to address GHG emissions," they wrote.

"When the 110th Congress begins in January, we pledge to work to pass an effective system of mandatory limits on greenhouse gases," the senators said.

"We urge you to work with us to reach this result and to signal to the world that global warming legislation is on the way," they added.

The trio also noted that diplomats from 189 countries, including the United States, were currently in Nairobi for the UN Framework Convention on Climate Change (UNFCCC).

"Unfortunately, we have not been satisfied with the level of US participation in the international negotiations or in reducing our own domestic greenhouse gas (GHG) emissions," they wrote.

"Therefore, as incoming Chairs of three important Senate Committees on global warming, we seek your commitment to work with the new Congress to pass meaningful climate change legislation in 2007," the senators said.

Boxer will chair the environment and public works committee, Bingaman will lead the energy and natural resources committee and Lieberman will head the homeland security and governmental affairs committee.