The Amazon is the planet's largest river system and the vast rainforest it waters — a natural force on a planetary scale that carries roughly a fifth of all the river water reaching the world's oceans, holds the richest concentration of living species on land, makes much of its own rainfall through a cycle of aerial moisture called flying rivers, and now sits close enough to a tipping point that its fate has become a question for the whole climate of the planet.
Every second, the Amazon River alone delivers into the Atlantic roughly a fifth of all the river water that reaches the world's oceans. That number is not a curiosity. It is a measure of a system so large it makes its own weather. The forest transpires so much water that the vapor rises, travels inland, and falls again as rain — watering itself. The Amazon is not simply a river. It is a machine. And the machine is now being dismantled.