It generates rainclouds that water some of the world’s most productive farmlands, from Argentina to Texas.
It also helps buffer us from global warming.
As our cars and power plants spew greenhouse gases into the atmosphere, the Amazon’s seemingly boundless plantlife has been soaking up some of that extra carbon.
But the world's largest rainforest is now in trouble.
In 2005, the upper Amazon was struck by the worst drought on record. Another followed in 2010.
Scientists say climate change is leading to less rain and higher temperatures. Meanwhile, logging and clear-cutting for agriculture, mining and other industries are accelerating the effect and further drying out the forest.
Tropical ecologist Greg Asner, with the Carnegie Institution for Science, has pioneered techniques to map changes in the forest from an airplane. His cutting-edge technology has shown dramatic changes in just a few years.
“The worst case is that we could lose almost all of the basin,” Asner says in this GlobalPost video that was filmed in the skies above the Amazon.