Cleaner Air May Threaten Amazon Rainforest

Reducing sulphur dioxide emissions linked to increasing risk of drought, scientists say

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WEDNESDAY, May 7, 2008 (HealthDay News) -- Cleaner air may actually threaten the Amazon rainforest, according to Brazilian and British climate scientists.

They claim that a reduction in coal burning and the resultant sulphur dioxide emissions is linked to increasing sea surface temperatures in the tropical north Atlantic, which increases the risk of drought in the Amazon rainforest.

The researchers said sulphate aerosol particles released by coal-burning power stations in the 1970s and 1980s partially reduced global warming by reflecting sunlight and making clouds brighter. This pollution has been mainly in the northern hemisphere and has acted to limit warming in the tropical north Atlantic, which has kept the Amazon wetter then it would otherwise be, the scientists explained.

"Reduced sulphur emissions in North America and Europe will see tropical rain-bands move northwards as the north Atlantic warms, resulting in a sharp increase in the risk of Amazonian drought," study co-author Chris Huntingford, of the Centre for Ecology and Hydrology at the University of Exeter in the United Kingdom, said in a prepared statement.

"These findings are another reminder of the complex nature of environmental change. To improve air quality and safeguard public health, we must continue to reduce aerosol pollution, but our study suggests that this needs to be accompanied by urgent reductions in carbon dioxide emissions to minimize the risk of Amazon forest dieback," study author Professor Peter Cox, of the University of Exeter, said in a prepared statement.

The study was published in the May 8 issue of Nature.

The Amazon rainforest contains about 10 percent of the total carbon stored in land ecosystems and recycles a large amount of the rainfall that it receives, according to background information in the study. Any major change to the Amazon's vegetation as a result of drought or deforestation has a major impact on the Earth's climate system.

"The rainforest is under many pressures. Direct deforestation is the most obvious immediate threat, but climate change is also a big issue for Amazonia. We have to deal with both if we want to safeguard the forest," study co-author Matthew Collins, of the Met Office Hadley Center in the United Kingdom, said in a prepared statement.

More information

The World Wildlife Fund has more about the Amazon rainforest.

SOURCE: University of Exeter, news release, May 7, 2008

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