Clean air could kill the Amazon, researchers say

By Michael Kahn

LONDON (Reuters) - Cleaner air due to reduced coal burning could help destroy the Amazon this century, according to a finding published on Wednesday that highlights the complex challenges of global climate change.

The study in the journal Nature identified a link between reduced sulphur dioxide emissions from coal burning and increased sea surface temperatures in the tropical North Atlantic that boosts the drought risk in the Amazon rainforest.

With the rainforest already threatened by development, higher global temperatures could tip the balance, they said.

"Generally pollution is a bad thing but in this case improving the air may have ironically led to a drying of the Amazon," said Peter Cox, a researcher at the University of Exeter in Britain, who led the study.

"It shows you have to deal with greenhouse gases."

The Amazon -- the world's largest tropical rainforest -- plays a critical role in the global climate system because it contains about one tenth of the total carbon stored in land ecosystems.

The researchers used a climate-carbon model to simulate the impacts of future climate change on the Amazon and compared it to data from a 2005 drought that devastated a large chunk of the rainforest.

They estimated that by 2025 a drought on the same scale could happen every other year and by 2060 such a crisis could hit nine out of every ten years -- enough to turn the rainforest into savannah grassland, Cox said.