Emissions from tropical rainforests are the elephant in the living room of climate change.

Twice as much carbon is stored in the trees as in the whole of the earth's atmosphere.

If that goes up in smoke, you can forget the whole caboodle, yet poor countries are burning forests like there is no tomorrow. Why do we argue over air travel when carbon from the next five years of burning rainforests will be greater than that for the entire history of aviation - and for at least the next two decades!

Grand Canopy Programme figures show deforestation accounts for up to 25% of global emissions of heat-trapping gases, while transport and industry account for 14%; and aviation makes up only 3% of the total.

One day's deforestation is equivalent to the carbon footprint of eight million people flying to New York. Reducing those catastrophic emissions can be achieved most quickly and most cheaply by halting the destruction in Brazil, Indonesia, the Congo and elsewhere.

Yet halting those emissions remains a minor part of the agenda, despite a report in January by the consultancy gurus, McKinsey, showing forestry offered the largest and most cost-effective opportunity for global action.

Clearly, forests should be first, not last in the debate - yet the same report buried forests under a mountain of technology-based solutions that developing countries can ill afford. What is going on?

When Kyoto was conceived, it seemed right that precautionary measures should focus on the industrialised nations first.

Heavy hitters in the NGO world lobbied to exclude forests from Kyoto to prevent industrialised nations from buying carbon credits in, say, the Amazon or Borneo.

The result has offered thesecountries no way of getting Kyoto credits from their forests other than by cutting them down and planting new ones.

Fortunately, a year ago the Coalition of Rainforest Nations demanded that it should be paid to stop cutting down forests.

Brazil has now put forward its own proposals for a rainforest credit scheme.

After 30 years at the conservation frontline, I fear that history may condemn our past efforts as little more than the "charge of the Light Brigade".

Now we must increase the value of rainforests to stand up to the power of rising global demand and we must harness commerce as an ally.

In January, I hosted a visit by Governor Braga of Amazonas State to London.

He was asking for help to save the biggest store of natural carbon on the planet. But the Amazon offers much more than carbon.

It acts like a global-scale utility, generating rain vital for Brazil's agriculture, hydropower stations and industry, while the forest canopies of the Amazon, Congo and Asia air-condition our atmosphere, buffer climatic conditions and give livelihoods to 1.6 billion people.

Marketing these ecosystem services could provide the added value forests need and help dampen the effects of industrial emissions.

Our global alliance of scientific organisations has set up the VivoCarbon Initiative to deepen our understanding of the vital roles played by living carbon, and today I am launching our first Report, which calls for increased incentives for sustaining rainforests, and mechanisms to pay for it.

There is nothing to be gained from allowing the folly of deforestation to continue.

Those countries wise enough to have kept their forests could find themselves the owners of a new billion-dollar industry.