The world must act now to curb climate change, as doing nothing will cost more long-term, UK officials have said.
Climate change could wipe out economic growth in some regions
British government official and former World Bank chief economist Sir Nicholas Stern said pursuing alternative energy made economic and environmental sense.
He was addressing a closed-door meeting in Mexico of representatives of 20 of the world's most-polluting nations.
The two-day gathering hopes to reach agreement on ways to meet future energy demands while cutting emissions.
The meeting in Monterrey is the latest round of talks on the climate action plan decided upon at the G8 Gleneagles Summit last year.
Ministers from G8 nations are joined at the event by representatives from the emerging economies of China, India, Brazil, and South Africa.
Organisers hope the meeting will be able to make progress on a number of issues, including:
- economic challenges of tackling climate change
- alternative low-carbon technologies
- level of investment from public and private sectors
- "road map" for a low-carbon future
British Environment Secretary David Miliband quoted findings reached by Sir Nicholas in his report, which was commissioned by the UK government.
"He shows that the longer action is delayed, the more expensive it is," Mr Miliband said.
"What he says is that... it is imperative we take action to prevent further climate change because the economic costs - never mind the human costs and the costs to the environment - will far outweigh the costs of mitigation."
Also at the meeting, Claude Mandil, head of the International Energy Agency (IEA), presented the findings of extensive research carried out by the agency.
Mr Mandil told the BBC that the technologies needed to cut emissions for the foreseeable future already exist.
However, he warned that investment in new low-carbon technologies was needed now - otherwise a fresh generation of inefficient, carbon intensive power stations would become locked into the global energy mix.
But he said that he was not optimistic that there was a political will to deliver the necessary support, and that there was "a huge gap between words and deeds".
Costing the Earth
The Ministerial Dialogue on Climate Change, Clean Energy and Sustainable Development was created by the UK when it held the presidency of the G8 in 2005.
One of the dialogue's aims was to attempt to reach an informal agreement between industrialised and developing nations on a long-term strategy to cut emissions.
The world's biggest polluter, the US, has not ratified the UN's Kyoto Protocol - the international agreement on reducing nations' greenhouse gas emissions.
President Bush rejected it, saying it would harm the US economy and fail to deliver any meaningful reductions.
Emerging economies, led by China, argued that if the world's richest nation was not part of the Kyoto targets, it was unfair to expect developing nations to be subject to legally binding limits.
Campaigners hope the Sir Nicholas' findings will help deliver a consensus among the big polluters.
"We are urging the G8 not to miss another opportunity to take action in favour of the poorest people of the world, who are already struggling to cope with the effects of climate change," said Rachel Roach, a climate change policy adviser for the aid charity Tearfund.
But she added: "Unfortunately, it may well be that this week's meeting is another case of lots of talk but little action."