As fires rage across the Amazon, a growing number of scientists are raising the alarm about a nightmare scenario that could see much of the world’s largest rainforest erased from the earth.

Climate change, along with the fires and other man-made forces, appear on the verge of triggering a significant change in the Amazon’s weather system.

No one knows for sure whether and when this might happen, though some scientists who study the Amazon ecosystem call it imminent. If it does happen, a body of research suggests, the Amazon as a whole would cross a tipping point and begin to self-destruct — a process of self-perpetuating deforestation known as dieback.

If that is left unchecked, half or more of the rainforest could erode into savanna, according to some estimates, and then the rainforest, which has long absorbed the world’s greenhouse gases, could instead begin to emit them.