Gordon Brown is this week attending two summits in the US to discuss climate change concerns with other world leaders.
The prime minister will be in New York on Tuesday for talks on global warming before heading to the G20 meeting in Pittsburgh at the end of the week.
The discussions aim to push forward plans that may be finalised at the Copenhagen summit in December.
On Wednesday he is also set to attend the meeting of the United Nations general assembly.
And Brown was due to telephone the Indian prime minister, Manmohan Singh, on Monday to discuss global warming as well as other international economic issues.
There has been growing concern that not enough is being done to combat the issue, with only 76 days remaining until the crunch talks in Denmark at the end of the year.
UN secretary general Ban Ki Moon wrote to 100 world leaders, including the British prime minister, asking them to support the 'TckTckTck' campaign by groups including Oxfam, Greenpeace and WWF, which also want a deal agreed in December.
Despite Brown expressing confidence that the meeting in Copenhagen will be successful, energy secretary Ed Miliband is concerned that the triumph still hangs in the balance. "I welcome the TckTckTck campaign," he said.
"With all to play for, the campaign can help us ramp up global pressure for the best possible climate deal in Copenhagen.
"I'll be pushing at every opportunity over the coming 80 days to get a deal, but we need leaders from across the UK to lend their support too."
Objectives for the summit include cutting carbon emission sufficiently to prevent dangerous temperature rises, securing funding to prevent deforestation and helping hard-hit poor countries cope with the impact of climate change.
