WASHINGTON (CNN) -- The world's tropical forests are disappearing, and one reason is simple economics: People, companies and governments earn more by logging, mining or farming places such as the Amazon jungle than by conserving them.



Global climate change treaty, scheduled for completion in December, is designed to protect tropical forests.



Efforts to halt rain forest destruction date back decades, but they so far have failed to tackle the issue on a scale commensurate with the challenge.



Now there may be a remedy, and the reason is climate change. Increased awareness of the threat from global warming has prompted unprecedented international focus on how to combat it, as well as new appreciation for the vital role of tropical forests in the climate change equation.



On Tuesday, world leaders gather at the United Nations for a special climate change summit, intended to build momentum for a new global climate change treaty being negotiated by almost 200 countries. The new treaty is scheduled to be completed in December in Copenhagen, Denmark.



If eventually enacted, the treaty will include a revolutionary but little-known provision intended to protect remaining tropical forests.



Known as Reduced Emissions from Deforestation and Degradation in developing countries, or REDD, the provision is based on the knowledge that destroying tropical forests contributes to global warming.



Rain forests absorb and store huge amounts of carbon dioxide, the most prevalent of the greenhouse gases that cause climate change. Burning or clearing the forests returns that stored CO2 to the atmosphere, where it can trap heat and gradually increase temperatures.



Every year, tropical forests equal to an area the size of England are destroyed, contributing about 20 percent of total annual greenhouse gas emissions -- more than all the world's cars, trucks and airplanes combined.



The idea of the proposed provision is to make the stored carbon dioxide in the forests a commodity that can be bought and sold on the global market.



Polluters in the developing world would be able to offset their emissions by buying credits for stored forest carbon dioxide. The money from those purchases would go to developing world governments, international organizations, local communities and others involved in forest protection programs.



For the first time, tropical forests would be worth money for simply existing. That could create an economic incentive to protect tropical forests, which also have biological value as the planet's richest storehouses of land species and spiritual worth as pristine natural landscapes.



To longtime defenders of tropical forests, the proposal represents the final stage of a long and halting journey from the fringes of the environmental movement toward the mainstream of international policy.



"Done properly, this is our No. 1 hope," said Randall Hayes, who founded the Rainforest Action Network in 1985 with the goal of halting tropical deforestation. "Other strategies have been heroic but insufficient."



The system would let nations and industries that are the biggest greenhouse-gas emitters buy carbon credits in tropical forests in South and Central America, Africa, Southeast Asia and other equatorial regions. At the same time, investors could speculate on the price of carbon dioxide through credit trading. Private and public funds could invest in projects that protect forests to generate credits.



Final details of the plan remain uncertain, such as how forest carbon credits would be verified and how the money paid for them would be handled and distributed.



For developing countries, the idea represents a potential new revenue source. President Bharrat Jagdeo of Guyana, a leading proponent of the plan, has made trading carbon credits a central element of his Low-Carbon Development Strategy.



The strategy "is more about development than about the environment and it will help us to accelerate infrastructural development and fill the budget gap," Jagdeo said in an August 29 speech.



The World Bank and partners have set up funds to help developing countries prepare for REDD and finance forest-protection initiatives. However, both funds are not fully capitalized, pending the successful conclusion of negotiations on the new global climate change treaty.



"Right now everybody is in a wait-and-see mode," said Benoit Bosquet, the World Bank's lead carbon finance specialist. "Everybody
Where have world leaders  gathered What dot he world leaders gather for? what Deforestation and Degradation provision has critics? What is the treaty based on What are they saying is destroying the tropical forests?
United Nations special climate change summit, Reduced Emissions from Global climate change logging, mining or farming
question: Where have world leaders  gathered, answer: United Nations | question: What dot he world leaders gather for?, answer: special climate change summit, | question: what Deforestation and Degradation provision has critics?, answer: Reduced Emissions from | question: What is the treaty based on, answer: Global climate change | question: What are they saying is destroying the tropical forests?, answer: logging, mining or farming