Amazonia is closer to a catastrophic ecological tipping point than any time in the last 100,000 years, and human activity is the cause.
In a new paper published today in the Annals of the Missouri Botanical Garden, Florida Tech biology professor Mark Bush describes how the vast Amazonian rainforest could be replaced by savanna, which is a grassland with few trees, within our lifetime.
Rainforests rely on high humidity and have no adaptation to withstand fire. Bush uses fossil pollen and charcoal recovered from lake sediments dating back thousands of years to track changes in vegetation and fire frequency through time. He has found that fires were almost unknown in Amazonia before the arrival of humans.
Relatively small-scale disturbances caused by the first inhabitants of Amazonia over the last 10,000 years did not bring the system to a tipping point because it could recover from these minor events. But