Man-made climate change is a clear and present danger. Decision-makers from around the globe will converge on Bali in a fortnight in an attempt to do something about it. And the call has gone out for the world's leaders to take bold action to avoid a catastrophe. Enter Guyana. The former British colony, sandwiched between Venezuela and Brazil, is home to fewer than a million people but it is also home to an intact rainforest larger than England. In a dramatic offer, the government of Guyana has said it is willing to place its entire standing forest under the control of a British-led, international body in return for a bilateral deal with the UK that would secure development aid and the technical assistance needed to make the change to a green economy.

The deal would represent potentially the largest carbon offset ever undertaken, securing the vast carbon sinks of Guyana's pristine forest in return for assisting the economic growth of South America's poorest economy. Speaking in his office in the capital, Georgetown, on the Caribbean coast, Guyana's President, Bharrat Jagdeo, said the offer was a chance for Britain to make a "moral offset" and underline its leadership on the most important single issue facing the world – climate change. "We can deploy the forest against global warming and, through the UK's help, it wouldn't have to stymie development in Guyana."

Mr Jagdeo, 43, said he was "looking for a partner to sit across the table with" to work out the precise terms of any deal, without compromising the country's sovereignty. "We are a country with the political will and a large tract of standing forest. I'm not a mercenary, this is not blackmail and I realise there's no such thing as a free lunch. I'm not just doing this just because I'm a good man and want to save the world, I need the assistance."

Mr Jagdeo, an economist by training, did not envisage long-term support from the British taxpayer but said the British government could help by lending its backing to private sector investments through the emerging carbon markets. "The market should ultimately compensate countries but in the absence of this, this is the best thing on the table. It would send a strong message to Bali that standing forests matter," he said.

The existing rainforest reserve of Iwokrama in central Guyana has been mentioned as a model for what could be done countrywide. The million-acre reserve was gifted to the Commonwealth in 1989 as a showcase for how tropical forests could be managed to provide ecological and economic benefits. Scientists working there estimate it holds close to 120 million tons of carbon – an amount equivalent to the annual emissions of the UK.

David Singh, chief executive of Iwokrama, said Guyana's offer has to be taken seriously: "When a sovereign state does this, it's something the world needs to pay attention to. Nowhere else is a state willing to place its forest into the hands of the international community for protection."

The accelerating destruction of the rainforests that form a cooling band around the earth's equator is recognised as one the main causes of climate change. Tropical deforestation accounts for one fifth of all carbon emissions, more than the entire transport sector – including the aviation industry. The burning of trees pumps as much carbon dioxide into the atmosphere as the US and has pushed Indonesia and Brazil into the world's top four polluters. Despite this, efforts to avoid deforestation were not included in the Kyoto protocol. That agreement is expiring and the UN climate change conference in Bali next month is tasked with thrashing out a successor that will work. The landmark Stern Review concluded that forests offer the single largest chance for cost-effective and immediate reductions of carbon emissions.

But the gap between rhetoric and reality remains large for smaller nations such as Guyana. "It infuriates me when I hear lofty speeches and back-patting in the developed world," said Mr Jagdeo. "Despite Stern, we are wondering whether they really believe that avoiding deforestation is the most cost-effective way to combat climate change."

Hylton Murray-Philipson, the head of London-based Rainforest Concern, said a deal could be a breakthrough. "In the absence of an international agreement, an early action by enlightened leaders should be greatly welcomed. Business as usual is not going to work." The former investment banker, who is working to bring funding into developing carbon markets, said: "It's insanity that a single service company, Google, has a market value of $200bn, while all the services of all of the world's great forests are valued at nothing."

Guyana is the only English-speaking country in South America and, with its history in the sugar trade and Caribbean links, is primarily a coastal culture. With a population of only around 750,000 in a country almost as big as the entire UK, it combines dense, species-rich forests with low population pressure.

But the soaring price of timber and gold, which is mined from forested areas, means pressure to exploit its most obvious resource is building. A Brazilian plan is on the drawing board to build a paved highway through the rainforest, a move that could turn Georgetown into a major port and change the face of the country. "Maybe we should just cut down the trees. Then someone would recognise the problem," said Mr Jagdeo. "But I want to think we can fulfil our people's aspirations without cutting down the trees."

Mr Jagdeo said the UK's leading role in achieving debt relief for Third World countries had inspired him to make the offer to London: "Ordinary people in Britain, the churches and NGOs put the issue squarely on the agenda. Then the British Government championed debt relief. This would send a signal that we are prepared to go beyond Kyoto. It could be a symbol of what can be done."

Iwokrama: the prototype which prospered
The outline of the Iwokrama rainforest reserve cannot be seen from the air. The green ocean of the forest canopy stretches uninterrupted in every direction. But the sanctuary, which takes its name from the language of the local Makushi people and means "place of refuge", is there and it's an extraordinary place.

Part of the Guyana Shield, one of the last four intact rainforests left in the world, it is home to mountains, 200 lakes, rivers flowing over volcanic dykes, lowland tropical rainforests and palm forests. The forest shelters some of the world's most endangered species, including the jaguar, harpy eagle, giant anteater, giant river otter, anaconda, black caiman and giant river turtle.

Iwokrama is more than a reserve. It is a living laboratory where science, conservation, tourism, biodiversity and the needs of the local community have come together in an experiment to sustainably manage the forest. It was set up after Guyana offered the one million acre site to the international community in 1989 and is run by local and foreign staff. David Singh, a Guyanese conservationist who has run the centre for three years, is convinced the experiment has been a success. "We have learnt how to do it and how not to do it – which is often the most expensive lesson," he says. "The international community could transform the way we use forests."

The centre attracted heavy funding in its early years but has struggled more recently as overseas donors shifted their attention from sustainable development into HIV and Aids projects. The scope of the scientific work undertaken at the reserve's field station has been scaled back and Guyana's government had to plunder its own meagre budget two years ago to keep the reserve going.

But the increasing attention now being paid to climate change is starting to make Iwokrama look like a project ahead of its time as it seeks to solve the conundrum of making its trees worth more standing up than they would be if they were cut down.

A mixture of eco-tourism, non-timber products and business ventures such as a butterfly farm are bringing in an income. Ron Allicock, a Makushi ranger at the centre, said: "People come here thinking the forest is empty, that the place is just full of trees. But it is also our home." He thinks Iwokrama could be a model for getting it right in forests around the world: "We've got to fix the small place first to show we can fix the big place."

(Por Daniel Howden in Georgetown, The Independent, 24/11/2007)