WWF's new review of scientific research on the Amazon and climate change says that climate-modelling studies are projecting a warmer and drier environment for the region, which will likely lead to a substantial decrease in precipitation over much of the Amazon. Such changes would result in significant shifts in ecosystem types - from tropical forest to dry savannah - and loss of species in many parts of the Amazon.
"A changing climate poses a substantial threat to the Amazon forests, which contain a large portion of the world's biodiversity. Threats here translate into threats to biodiversity at large," said Beatrix Richards, forests expert at WWF.
"The world needs to urgently evaluate vulnerability to climate risks and integrate them into biodiversity conservation efforts."
The combination of human activities - such as land clearing for agriculture and logging - and climate change increases the drying effect of dead trees that fuels forests fires.
In the absence of effective measures, global warming and deforestation could convert from 30 up to 60 per cent of the Amazon rain forest into a dry savannah, according to research carried out under the auspices of Brazil's National Space Research Institute (INPE).
The climate in northwestern South America, including the Amazon region, has already changed over the last century: For example, the average monthly air temperature records have increased by 0.5-0.8°C from 1990 to 2000.
"We are running a serious risk of losing a large piece of the Amazonian tropical forest," said senior INPE scientist Carlos Nobre.
"If warming exceeds a few degrees Celsius, the process of 'savannisation' may well become irreversible."
Currently, the Amazonian forests act as an important sink for carbon dioxide (CO2), a gas emitted mainly from the burning of fossil fuels coal, oil and natural gas, and the major driver of global climate change. However, up to about 20 per cent of CO2 emissions worldwide stem from deforestation - in particular cutting down and burning wood. If its destruction continues, the Amazon rainforest could become a net source of CO2.
Governments should send a powerful political signal about the need to protect the world's biodiversity and climate. WWF presents the review to the 8th UN Conference of the Parties to the Convention on Biological Diversity (COP8), at which countries of the Amazon basin must announce measurable commitments to reduce deforestation.
"Both the burning of fossil fuels and deforestation must be urgently and significantly reduced in order to save the world's biodiversity and people from catastrophic climate change," said Giulio Volpi, coordinator of WWF's Climate Change Programme for Latin America and the Caribbean.
"Here in Curitiba, there is a unique opportunity to address the deadly combination of deforestation and climate change. Amazon countries need to commit to stop deforestation, for the benefit of present and future generations."
Cows in burnt rainforest, Brazil
"If warming exceeds a few degrees Celsius, the process of 'savannisation' may well become irreversible."Carlos Nobre, senior INPE scientist