Illegal logging in the Amazon continues to devastate the rainforest. Brazilian authorities recently seized tons of mahogany wood cut illegally from indigenous lands in a northern Amazon state.

The distinctive roar of a chainsaw breaks the silence of the jungle. The saw's metal teeth bite deeply into the trunk of a huge tree, scattering clouds of yellow sawdust into the air. Eventually, the chainsaw cuts through the large, round trunk, and with a shudder the tree crashes to the ground. It is a scene that is repeated time and again in the Amazon rainforest, as large primary growth trees are felled and processed for their valuable timber.

Some of the logging is legal, and is done in a sustainable manner. But most of it is illegal. Of the 30 million cubic meters of timber harvested from the Brazilian rainforest each year, 80 percent is cut down illegally. Paulo Adario of the environmental organization, Greenpeace, says illegal logging exists because Brazilian authorities have few resources to stop it. "In Amazonas state they have one inspector for each four million hectares; this is one inspector for each Switzerland," he says. "So the logging companies can operate knowing that the state will not be there to help enforce the law, or to control them, and this explains the illegality of this."

In the northern state of Para late last month, agents from Brazil's environment agency, IBAMA, seized 7,000 cubic meters of mahogany, which had been cut down illegally in an Indian reserve. The seizure, carried out with the help of Greenpeace, was part of a wider campaign called "Operation Mahogany". But such seizures are rare, and illegal logging continues unabated.

An estimated 550,000 square kilometers of land in the Amazon has been deforested much of it as a result of illegal logging. Mr. Adario says the pace of deforestation has increased exponentially during the past few decades. "When the Portuguese arrived here in 1500, and until 1970, only one percent of the Amazon was deforested or destroyed. In the last 30 years, 15 percent of this region was totally deforested," he says. "This is an area larger than France, in only 30 years, and the logging industry contributed a lot to this process." But so did roads and highways.

Since the mid-1960's, highways have been built in the Brazilian Amazon to help foster economic development. They connect once isolated towns and cities to the rest of the country. But along with development has come deforestation.

The Brazilian government has plans to build and pave an additional 6,000 kilometers of roads in the Amazon in coming years, under a program called "Forward Brazil". But scientists warn that more roads will bring greater destruction.

Philip Fearnside is an ecologist at Brazil's National Amazonian Research Institute in Manaus, a group known as INPA. "If you build highways and so forth, opening up areas that are not accessible now, then that sets in motion a process that is largely outside the control of the government: people moving in and clearing, and reselling the land," he says. "Land values go up and you have speculation motivating deforestation and so it is not something that destroys the Amazon in one blow, but it is something that adds significantly to the amount you can expect to be lost over the next few decades."

Mr. Fearnside was one of the authors of a study released early this year that projected a serious loss of rainforest during the next 20 years, if present trends continue. The study, by Mr. Fearnside and other scientists at INPA, predicted that only 28 percent of the primary growth rainforest would remain standing by the year 2020 under the most optimistic scenario. Under the most pessimistic prediction, less than five percent would remain. "With the non-optimistic scenario basically all that is left that is undisturbed is the central and western part of the Amazon, that are large blocs without access. But everything east of Manaus, more or less, is disturbed in some way," says Mr. Fearnside. "With the optimistic scenario there are some patches between these major access routes in the central and eastern portion which survive. The disturbances themselves are huge, around 1.5 million hectares of disturbance in the non-optimistic scenario."

Deforestation also contributes to global warming as the land is cleared for farming by burning the jungle, or letting the destroyed vegetation decay. Mr. Fearnside estimates about 200 million tons of greenhouse gases, such as carbon dioxide, nitrous oxide, and methane, would be emitted under the non-optimistic scenario projected in the INPA study. "The role of Brazil for these greenhouse gas emissions is of two types: one is the amount of emission that is occurring now, which is substantial, and the other is how much could occur in the future," he says. "Brazil still has a tremendous amount of forest that is still standing so that represents a big stock of carbon that can be released into the atmosphere in the future, and any changes that are made in policies that affect how deforestation proceeds in Brazil will have a major effect on what happens over the next few decades."

These views are fueling an ongoing debate in Brazil, which pits those advocating further development in the Amazon against those arguing for greater preservation. So far, the forces of development are winning.