Forests do not always act as carbon sinks. A study of the Amazon rainforest, conducted by Oliver Phillips and 67 other scientists from 40 institutions, showed that warmer Atlantic waters caused such arid conditions in the western and southern parts of the Amazon in 2005 that younger trees died and growth in older ones slowed.
Instead of absorbing 500 million tonnes of carbon dioxide (CO2) a year, the Amazon rainforest released 900 million tonnes of CO2, the scientists found. The researchers are now looking at whether the trees have returned to being net absorbers of CO2.
Sandy Andelman, co-author of the study entitled Drought Sensitivity of the Amazon Rain Forest and Vice-President of the Tropical Ecology, Assessment and Monitoring (TEAM) Network at Conservation International, commented on the report: ôWith most of the climate change debate focusing on energy security and food security, this study emphasizes the fundamental importance of ecosystem security ľ in short, how nature keeps us healthy. It shows that a warming climate is not the only problem; drying climate is just as bad or worse for both nature and people. More than half the species on Earth and at least 2 billion people depend directly on tropical forests for survival. At the same time, the great remaining forests of Africa's Congo Basin and the Amazon region of South America play a vital role in climate regulation by absorbing and storing huge amounts of atmospheric carbon. Now the study reveals that increasing drought due to global climate change can cause potentially irreparable damage to the Amazon jungle and its ability to function as a carbon sink."
The sensitivity of forests to climate fluctuations may impair efforts to reduce carbon emissions. Only two weeks prior to the publication of this report, scientist Simon Lewis, another co-author of this report, said that tropical rain forests will probably slow their absorption of CO2 in the coming decades due to aging.
Higher temperatures in the Atlantic are also said to have spawned severe storms in the Caribbean in 2005, including Hurricane Katrina.