Research showed that the Amazon rainforest does not hold back global warming by absorbing carbon dioxide (CO2), as previously thought. It is actually 'carbon neutral'. Its rivers and wetlands 'breathe out' as much CO2 as its drier airs 'breathe in'. The discovery merely confirmed that Nature finds its own delicate balance, and that humankind disturb that at their peril. It is often impossible to predict the effect of our actions.

Excessive logging, for instance, would certainly reduce the amount of carbon dioxide (CO2) absorbed by the trees, just as draining Amazonian wetlands might reduce CO2 emissions. But Nature is more complex. For instance, deforestation increases soil erosion, leading to more organic matter washed into rivers and swamps. There the organic matter decomposes, releasing various greenhouse gases. This might increase the amount of CO2 released into the atmosphere.

But deforestation and soil erosion also lead to sediment washed into rivers and swamps. The sediment might cover the organic matter, actually reducing the wet areas' CO2 emissions.