Environment and energy ministers from 20 countries are meeting in the UK to discuss climate change and how to reduce dependence on fossil fuels.
Green technologies will be a major topic of discussion
As well as representatives from the G8 group of rich nations, ministers from emerging economies such as China, India and Brazil are taking part.
The two-day brainstorming session, which will take place in London, will not involve binding commitments.
Instead, ministers will exchange ideas and discuss new technologies.
Britain has made tackling global warming a priority for its presidency of the Group of Eight industrialised nations - and Prime Minister Tony Blair has said that securing US support poses a significant diplomatic challenge.
"There is an attempt to draw the United States in after its refusal to [ratify] Kyoto," said a Greenpeace spokesman.
"It is very sensitive given that the developing countries are trying to climb the development curve and the developed countries must not be seen to be doing anything to hold them back."
The Kyoto treaty, which came into effect last month, aims to cut the carbon dioxide (CO2) and other greenhouse gas emissions of industrialised nations to 5% below 1990 levels by 2012.
But the US administration has argued that meeting the target would cost millions of US jobs, many of them "exported" to developing countries where pollution would continue anyway.
"The target that was given to the United States was so unreasonable in our ability to meet it that the only way we could have met it was to shift energy intensive manufacturing to other countries," James Connaughton, head of the White House Council on Environment Quality, told the BBC.
"That has economic effects and that also has job effects."
Mr Connaughton repeated Washington's demand for greater investment in scientific research to boost green technologies, so that economies could grow without damaging the environment.
"The [Kyoto] protocol was well intentioned, but I think it produced some quite consequential, unintended effects and we are trying to now find a portfolio in which three words are important: technology, technology and technology," he said.
The challenge of developing such technology is likely to dominate discussions on Tuesday. Tony Blair, like Washington, is encouraging countries to boost research into green technology.
He also wants to build a solid international consensus that global warming poses a serious threat, and that it is caused by greenhouse gas emissions. However, Mr Connaughton appeared to have reservations about a direct scientific link.
He told the BBC: "We are still working on the issue of causation, the extent to which humans are a factor, but they may be, as well our understanding of what effects may result from that over the course of the next century."