Amazon carbon sink threatened by drought( This release is available in a href...)

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The Amazon is surprisingly sensitive to drought, according to new research conducted throughout the world's largest tropical forest. The 30-year study, published today in Science, provides the first solid evidence that drought causes massive carbon loss in tropical forests, mainly through killing trees.

"For years the Amazon forest has been helping to slow down climate change. But relying on this subsidy from nature is extremely dangerous", said Professor Oliver Phillips, from the University of Leeds and the lead author of the research.

"If the earth's carbon sinks slow or go into reverse, as our results show is possible, carbon dioxide levels will rise even faster. Deeper cuts in emissions will be required to stabilise our climate."

The study, a global collaboration between more than 40 institutions, was based on the unusual 2005 drought in the Amazon. This gave scientists a glimpse into the region's future climate, in which a warming tropical North Atlantic may cause hotter and more intense dry seasons.

The 2005 drought sharply reversed decades of carbon absorption, in which Amazonia helped slow climate change.

In normal years the forest absorbs nearly 2 billion tonnes of carbon dioxide. The drought caused a loss of more than 3 billion tonnes. The total impact of the drought - 5 billion extra tonnes of carbon dioxide in the atmosphere - exceeds the annual emissions of Europe and Japan combined.

"Visually, most of the forest appeared little affected, but our records prove tree death rates accelerated. Because the region is so vast, even small ecological effects can scale-up to a large impact on the planet's carbon cycle," explained Professor Phillips.

Some species, including some important palm trees, were especially vulnerable", said Peruvia
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