The Amazon Rain Forest, "lungs of the planet", is predicted to disappear when climate change rise hits 4°, all other things being equal. But human forcing factors such as deforestation and fire use weaken the hydrological cycle upon which the forest depends (especially the volume of transpiration). As nonlinear forcing factors act in synergy, we're already seeing symptoms of a switch from forest to a non-forest regime. After tipping points are crossed, a complex system oscillates before permanently shifting to the new regime.
Severe droughts and floods signal that a systems bifurcation has been crossed. Such oscillations in the history of a complex system are called squealing (variance amplification near critical points). Expect a sudden shift, a die-off of the rain forest which provides 20% of our global oxygen, around 20 to 25% deforestation. In the diagram below, squealing occurs when the system is right on the dotted line between basin a and c.
In recent decades, new forcing factors have impinged on the hydrological cycle: climate change and widespread use of fire to eliminate felled trees and clear weedy vegetation. Many studies show that in the absence of other contributing factors, 4° Celsius of global warming would be the tipping point to degraded savannas in most of the central, southern, and eastern Amazon. Widespread use of fire leads to drying of surrounding forest and greater vulnerability to fire in the subsequent year.
We believe that negative synergies between deforestation, climate change, and widespread use of fire indicate a tipping point for the Amazon system to flip to non-forest ecosystems in eastern, southern and central Amazonia at 20-25% deforestation.
The severity of the droughts of 2005, 2010 and 2015-16 could well represent the first flickers of this ecological tipping point. These events, together with the severe floods of 2009, 2012 (and 2014 over SW Amazonia), suggest that the whole system is oscillating. [emphasis mine]
So far, the Amazon's deforestation level is at 17 percent, which is dangerously close to the new tipping point. If changes are not made, the Amazon could very well be at the point of no return.
"There is no point in discovering the precise tipping point by tipping it."
Its health is directly linked to the very planet's health, as its rainforests contain about 140 billion metric tons of carbon. If deforestation ensues, the release of this contained carbon could lead to catastrophic results for the entire planet. Furthermore, the Amazon is also home to over 30 million people who rely on its resources for shelter, food, and livelihood.
Apart from major deforestation, unsustainable mining, poorly planned infrastructure, and extensive agricultural expansion are also threats to the Amazon rainforest. [emphasis mine]
Photographed is the deforestation as a result of gold mining projects in the Amazon Rainforest.