Countries that stand in the way of a global warming treaty now risk international isolation because of the US's new commitment under Barack Obama to reaching a deal, the climate change secretary, Ed Miliband has said.

Miliband, who was in Washington this week, meeting members of Obama's green team, said the change in the administration had dramatically improved the prospects for reaching an agreement at a UN summit in Copenhagen in December.

"There is a real important point about the change that Obama creates and that is that nobody really wants to be the country that wrecks this global deal," Miliband said.

Obama campaigned on a promise to commit America to a climate change treaty and to create new green jobs. His predecessor, George Bush, made America a climate change pariah by rejecting the Kyoto protocol, arguing that it would hurt US business interests while making no demands on emerging economies like China and India. Other nations were able to point to the non-cooperation of the US, then the world's biggest polluter, as a reason for inaction.

The Obama White House's determination to seal a deal, restated even as the Administration seeks ways to combat the economic recession, has raised optimism about the prospects at Copenhagen, Miliband said.

"There is a real determination in the administration to try to meet the December 2009 deadline for an agreement and I think that is incredibly encouraging," he said. "There is a real sense of optimism that has created not just in Washington but in Europe and elsewhere."

Miliband said he discussed co-operation on the development of carbon capture and storage (CCS) technology, which could bury emissions from coal power stations, with the US energy secretary, Steve Chu. The US and UK are to hold a summit next month to try to push ahead with those efforts.

Britain's climate change secretary said it was in the interests of both Britain and America to try to research as wide a range of technologies as possible to produce the "clean" coal power he believes will be needed in the future.

"We have to join together all the intelligence there is on carbon capture and storage," he said. "We need to look at all the different technologies that exist. "

CCS technology is unproven at commercial scale and will be costly to develop, but many see it as essential given that countries with large coal reserves, such as the US and China, are very likely to rely on those reserves for power.

Obama has cast the pressures of climate change and economic recession as an opportunity. He argues that it is possible to craft a short-term fix with policies that would lay the foundation for a low carbon economy.

His $787bn recovery package contains some $100bn in green investment for insulating federal government buildings and private homes, upgrading America's electrical grid, expanding public transport, and research for clean coal technology.

The administration describes the green aspects of the recovery plan as a first step towards that new economy promised by Obama. It is looking to Congress to pass legislation later this year to expand the use of renewable energy such as wind and solar.

The White House has also been working closely with Congress to try to build political support for a global climate change treaty. Despite those efforts, however, administration officials admit that there may not be the political support in Congress to pass legislation reducing greenhouse gas emissions before Copenhagen.

Some leaders, such as Denmark's climate minister, Connie Hedegaard, argue America will be unable to play a leadership role without that tangible demonstration of commitment.

However, Miliband said America could still lead. "What is really important is that the US shows ambition to get a global deal and shows ambitions in its commitment," he said. "They are serious about this and they mean business."