An interlinked and frightening triad of rising temperatures, escalating deforestation, and wildfire is pushing the Amazon rainforest ever closer to a “tipping point” that will effectively destroy much of the precious ecosystem that is also one of the world’s critical carbon sinks, two renowned rainforest experts warn.
“The precious Amazon is teetering on the edge of functional destruction and, with it, so are we,” wrote Thomas Lovejoy of George Mason University and Carlos Nobre of the University of São Paulo, in a December editorial in the journal Science Advances.
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Lovejoy and Nobre were moved to sound their “dire alarm”, reports the Washington Post, “after witnessing the acceleration of troubling trends,” especially the region’s spiking temperatures. According to Nobre, “in the southern Amazon dry season in particular, temperatures are already 3.0°C higher than in the 1980s, and the dry season is getting longer, exceeding four months in some regions.”
Escalating rates of deforestation, together with devastating wildfires, are compounding the crisis.
With deforestation rates in the Brazilian Amazon close to 20%, writes the Post, “the fear is that soon there will be so little forest that the trees, which not only soak up enormous quantities of rainwater but also give off mist that aids agriculture and sustains innumerable species, won’t be able to recycle enough rainfall.”
Should the water cycle collapse in this way, “much of the rainforest could decline into a drier savanna ecosystem”. That shift would in turn change rainfall patterns across much of South America, release several hundred billion tons of carbon dioxide into the atmosphere, and further fuel climate change. “Such a feedback loop would be tough to reverse,” adds the Post.
While it can be “tricky” to assess how close the Amazon is to “tipping over” into savannah, University of California Irvine tropical ecologist Paulo Brando said “we’re probably driving very fast toward” the shift from rainforest to grassland. Nobre agreed the tipping point is “much closer than we anticipated”.
But Nobre and Lovejoy aren’t giving up hope, noting that aggressive reforestation could slow down the devolution of the Amazon rainforest.
“A tipping point is a way to talk about a moment of system shift or system change,” Lovejoy told the Post. “In this case, it’s not going to be instantaneous, and that’s good news. It allows you to do something about it.”