Deforestation and other fast-moving changes in the Amazon threaten to turn parts of the rainforest into savanna, devastate wildlife and release billions of tons carbon into the atmosphere, two renowned experts warned Friday.

“The precious Amazon is teetering on the edge of functional destruction and, with it, so are we,” Thomas Lovejoy of George Mason University and Carlos Nobre of the University of Sao Paulo in Brazil, both of whom have studied the world’s largest rainforest for decades, wrote in an editorial in the journal Science Advances. “Today, we stand exactly in a moment of destiny: The tipping point is here, it is now.”