Washington - Under pressure from the Obama administration to show the world that Washington is making advances against climate change, Congress is to open debate on a "clean energy" bill this week.
The United States is "now ready to lead" on climate change, President Barack Obama said earlier in April, and after a two-week legislative recess during which the administration made moves on climate change, Congress has little time to spare.
On Friday, the US Environmental Protection Agency said carbon dioxide and other greenhouse gases pose a health risk, a landmark turnaround that could impact climate change regulation.
The move came as Congress examines a draft bill for clean energy development that aims to cut carbon emissions by 20 percent from their 2005 levels by 2020, and boost reliance on renewable sources of energy.
The Obama administration wants the bill completed by the end of 2009, with the US president planning to travel to Copenhagen for the United Nations climate change conference in December.
Democratic House Speaker Nancy Pelosi has vowed Congress will seek a "comprehensive solution" to global warming.
"I am committed to moving clean energy legislation this year that will include perspectives from across our nation to create jobs, improve our national security and reduce global warming," she said in a statement.
The first step in the huge endeavour begins Tuesday, when the House Energy and Commerce Committee takes up four days of hearings. The committee's chairman, Democratic Representative Henry Waxman, and fellow Democrat Ed Markey are sponsoring the draft bill.
On Wednesday, lawmakers will hear testimony from EPA chief Lisa Jackson, Energy Secretary Stephen Chu and Transportation Secretary Ray LaHood.
Former vice-president Al Gore, a major climate change campaigner, is set to testify on Friday.
The president made tackling carbon emissions one of the centrepieces of his campaign, contrasting sharply with the administration of George Bush, which repeatedly cast doubts on the existence of global warning.
The US goals also call for a cap-and-trade system to cut carbon emissions in order to force heavy polluters to buy credits from companies that pollute less, creating financial incentives to fight global warming.
The quotas have yet to be defined, with some calling for free rights to pollute for the most vulnerable industries, such as steel or glass manufacturing.
The battle looming in Congress promises to be a tough one, with Republicans and some Democrats from coal- or oil-producing states warn of potentially catastrophic economic impacts from setting limits on emissions of greenhouse gases blamed for global warming.
The Democratic majority in the House hopes to secure a vote on the bill before a congressional recess in August, according to a Democratic source.
No dates have been set on the Senate's calendar.