Surrounded by mountainous plateaus on most sides, much of the basin is remote and difficult to access. In spite of its vast size and clear significance to the planet, there is much about the Amazon that remains enigmatic because it is such a complex and challenging place to study. Enough moisture rises out of the Amazon to supply vast “flying rivers” and about half of the rain that falls back down on the region, explained Thomas Lovejoy, a professor at George Mason University and a senior fellow at the UN Foundation for Science, Economics, and the Environment. It also pumps huge quantities of water into the air through a process called transpiration.

The Amazon rainforest is also an enormous carbon sink-an area that draws down carbon from the atmosphere. It is also home to more than 30 million people, including hundreds of indigenous groups and several dozen uncontacted or isolated tribes. The rainforest, which covers about 80 percent of the basin, is home to one-fifth of the world’s land species, including many found nowhere else in the world. It is home to Earth’s largest rainforest, as well as the largest river for the volume of the flow and the size of the drainage basin.

It spans at least 6 million square kilometers (2.3 million square miles), nearly twice the size of India. Please read part 2, part 3, and part 4 for a more complete picture of Amazon deforestation. Editor’s Note: This story is the first part in a series.

Amazon images