Page last updated: 14 May 2008
By BBC's Latin America Analyst James Painter
The rainforests are essential for removing carbon dioxide from the air
As concerns grow about global warming and the future of the planet, much more international attention is being paid to the Amazon region.
There are three fundamental reasons why the region is important to the rest of the world.
The Amazon and the world's climate
It is not surprising that the Amazon region is often called the "lungs of the world," as it plays a critical role in the global carbon cycle that helps to shape the world's climate.
About 200 billion tonnes of carbon are locked up in tropical vegetation around the world, of which about 70 billion tonnes are estimated to be in Amazon trees.
Rapid rates of deforestation cause more carbon to be converted into carbon dioxide, either when the trees are burnt down or more slowly by the decomposition of unburned wood.
And once the forests are gone, they cannot soak up the carbon from cars, power plants and factories. At the moment the Amazon is thought to absorb about 10 per cent of global fossil fuel carbon dioxide emissions.
Burning is leading to a vicious circle of carbon release
The build-up of carbon dioxide in the earth's atmosphere is one of the key causes of global warming. About 20 per cent of annual global greenhouse emissions is estimated to come from the clearing of tropical forests around the world.
According to the Stern Report on the economics of climate change, the loss of natural forests around the world contributes more to global emissions each year than the transport sector.
Brazil, for example, is ranked in the top five of the world's largest emitters of greenhouse gases, not because of its high emissions from fossil fuels but because of deforestation.
A study released in February 2008 by a team of international scientists from Oxford University, the Potsdam Institute and others concluded that the Amazon rainforest was the second most vulnerable area in the world after the Arctic.
The loss of the Amazon is leading to the loss of the Arctic
The essential idea is that the drying of the Amazon and/or increased deforestation could cause what is called "dieback" of the rain forest and a vicious cycle - a large reduction in the area of Amazon rainforest could cause a significant rise in CO2 emissions, which in turn would raise global temperatures - which in turn would cause more drying of the Amazon.
Scientists and climate change modellers disagree how soon a tipping point might happen or how likely it is. But however low the probability, changes to the Amazon are likely to be a "high impact" event on the world's climate.
The Amazon is the world's largest tract of tropical rainforest, containing the Earth's greatest biological reservoir - around 30 percent of all terrestrial species are found there.
The region is the main reason why Brazil is the most bio-diverse country in the world, with more than 50,000 described species of plants, 1,700 species of birds and between 500 and 700 different types each of amphibians, mammals and reptiles.
All this rich biodiversity is now being threatened by the destructive combination of stress from climate change and deforestation. Even though there are many unknowns about the Amazon's future and its effect on the world's climate, scientists agree that because of its biodiversity and the crucial role the region plays in shaping the climate, it is a matter of great urgency to find the right policy mix to conserve enough of the forest.