Both the most recent draft of the agreement and the climate bill passed by the House in late June in the United States include plans for rich countries and companies to pay the poor to preserve their forests.

The payment strategies may include direct payments to landowners to keep forests standing, as well as indirect subsidies, like higher prices for beef and soy that are produced without resorting to clear-cutting. Deforestation creates carbon emissions through fires and machinery that are used to fell trees, and it also destroys the plant life that helps absorb carbon dioxide emissions from cars and factories around the globe.

But getting the cash incentives right is a complex and uncharted business. In much of the developing world, including here, deforestation has been tied to economic progress. Pedro Alves Guimarães, 73, a weathered man sitting at the edge of the region’s River of the Dead, came to Mato Grosso in 1964 in search of free land, pushing into the jungle until he found a site and built a hut as a base for raising cattle. While he regrets the loss of the forest, he has welcomed amenities like the school built a few years ago that his grandchildren attend, or the electricity put in last year that allowed him to buy his first freezer.

Also, environmental groups caution that, designed poorly, programs to pay for forest preservation could merely serve as a cash cow for the very people who are destroying them. For example, one proposed version of the new United Nations plan would allow plantations of trees, like palms grown for palm oil, to count as forest, even though tree plantations do not have nearly the carbon absorption potential of genuine forest and are far less diverse in plant and animal life.

“There is the capacity to get a very perverse outcome,” said Sean Cadman, a spokesman for the Wilderness Society of Australia.

Global as well as local economic forces are driving deforestation  Brazil and Indonesia lead the world in the extent of their rain forests lost each year. The forests are felled to help feed the world’s growing population and meet its growing appetite for meat. Much of Brazil’s soy is bought by American-based companies like Cargill or Archer Daniels Midland and used to feed cows as far away as Europe and China. In Indonesia, rain forests are felled to plant palms for the palm oil, which is a component of biofuels.