The US:The Bush administration welcomed the United Nations climate change report and said the human role in global warming is no longer debatable but rejected mandatory caps on greenhouse gas emissions.
Energy Secretary Samuel Bodman said he "strongly supported" the report but refused to budge from Washington's long standing opposition to laws limiting the production of gases such as carbon dioxide.
"Does it make sense to try to put a cap on carbon emissions in this country that would cause damage to this economy and move the industries and the jobs abroad? It doesn't make sense to me. The US economy is not something to be experimented with," he said.
The Democratic-led Congress has identified the battle against global warming as one of its priorities and Democrats have introduced a number of Bills requiring industrial companies to reduce their emissions by a specified amount over time or introducing a system of emissions trading.
California senator Barbara Boxer said the UN report reinforced the argument that mandatory restrictions are needed to avoid a disaster in the future. "This report must serve as a wake-up call to those policymakers who have ignored this issue - we must take action now," she said.
Democrats this week accused the White House of withholding evidence they say will show how administration officials downplayed the dangers of global warming in research reports.
The allegations focus on Philip Cooney, a former lobbyist for the American Petroleum Institute who became chief of staff of the White House Council on Environmental Quality.
Mr Bodman insisted that the president, who spoke about climate change in his State of the Union address last month, is serious about reforming US energy policy.
In the short term, Mr Bodman said, there is a need for more research into hydrogen, solar power and ethanol production technologies.
Longer-term solutions would involve the creation of a new generation of nuclear power plants and coal-fired generators that don't release carbon into the atmosphere.
General Electric and DuPont were among 10companies that last month urged the administration to limit carbon emissions to reduce global warming pollution by as much as 30 per cent within 15 years.