Pinpointing Amazon forest tipping in global warming and deforestation pathways

Humanity is putting unprecedented pressures on the Amazon forest systems due to global warming, deforestation, land-use change as well as large-scale infrastructure projects. Since the Amazon forest may possess a tipping point beyond which detrimental changes are self-propelling, these pressures could lead to system-wide state changes across major parts of the Amazon forest. We apply a dynamical systems model to assess the tipping risks and cascading transitions in the Amazon forest systems under different shared socio-economic emission and land-use change pathways (SSPs). For these emission scenarios, we constructed the according atmospheric moisture transports within the Amazon forest using a state-of-the-art moisture tracking model. Without deforestation, we find a critical threshold of 3.7-4.0°C of global warming where adaptive capacities of the forest may be surpassed such that around a third of the Amazon forest loses stability. However, when taking into account deforestation, our simulations robustly find a near system-wide tipping point of the Amazon forest (62-77% of the area) between 1.5-1.9°C of global warming and deforestation between 22-28%. These are values that humanity may reach already within the first half of this century, and possibly as early as in the 2030ies. Importantly, the large majority of the observed tipping events in our model (87-99%) are caused by knock-on effects from increasing drought intensities, leading to long-ranging and self-propelling cascading effects on scales of hundreds to thousands of kilometres. Overall, our results underscore the necessity to keep global warming to below 1.5°C as well as stop deforestation (around 15%) and restore these areas to avoid high tipping risks across the Amazon forest.