The United States has formally affiliated with the Copenhagen Accord and pledged to cut its carbon emissions "in the range of 17 per cent" from 2005 levels, conditional on Congressional action on climate legislation.
In a letter to the UN Framework Conventional of Climate Change Secretariat on Thursday, chief US negotiator Todd Stern said the "pathway" in that pending legislation would cut US emissions 30 percent by 2025, 42 per cent by 2030, and 83 per cent by 2050.
Those are the levels President Barack Obama offered in a deal with China, India, South Africa, Brazil - known as the BASIC Group - at the Copenhagen climate conference held last month. While achieving the levels needs Congressional action, the accord itself does not.
Stern wrote, "The US submission reflects President Obama's continued commitment to meeting the climate change and clean energy challenge through robust domestic and international action that will strengthen our economy, enhance our national security and protect our environment."
Stern said the US is affiliating under the assumption that other industrialised nations and large emerging economies will follow through with the deal reached Dec 19 at Copenhagen and also affiliate.
"We expect that all major economies will honour their agreement in Copenhagen to submit their mitigation targets or actions," he said.
The summit had asked nations to report by Jan 31 whether they would associate themselves with the accord and join efforts to draft a successor to the Kyoto Protocol, whose legal obligations run out at the end of 2012.
After a meeting in New Delhi on Jan 24 BASIC environment ministers said they would respect the deadline to submit plans for 2020 emissions and challenged donors to deliver on aid promises.
The United States is the only major industrialised nation to shun the Kyoto Protocol. Former president George W Bush argued that it was too costly and unfair even as it made no demands of fast-growing emerging economies such as China and India.
The US submission came hours after Obama made his first State of the Union address, where he urged a joint session of Congress to move ahead on climate legislation. The Senate has yet to vote on climate legislation, which squeaked through the House of Representatives in June.
In the State of the Union address, Obama did not specifically ask the Senate to approve the House vision of a "cap-and-trade" system-in which companies must curb emissions and have an economic incentive by trading credits.