Source not sinks

The rivers and wetlands of South America's Amazon rainforest breathe out as much carbon dioxide into the atmosphere each year as the dry regions of the forests absorb, shows a new research. This suggests that, as a whole, the Amazonian and other tropical forests are in a state of carbon dioxide equilibrium. Because carbon dioxide is an important greenhouse gas, this could help scientists work out how deforestation and industrial activity affect global warming. "Now that we have identified another source of carbon dioxide it makes the whole system appear a little bit more sensitive to disturbance,' says Jeffrey Richey of the University of Washington in Seattle, USA.