Background atmospheric CO2 regulates the local and non-local climate impacts of Amazon deforestation

Amazon deforestation has substantial impacts on the climate system, yet the extent to which future atmospheric CO2 trajectories modulate these impacts remains unclear. Here, we assess the climatic impacts of Amazon deforestation under contrasting atmospheric CO2 scenarios using the Community Earth System Model version 2 (CESM2). Experiments were conducted with two land cover scenarios (a control and a business-as-usual Amazon deforestation scenario) combined with high and low CO2 emission pathways for the period 2050−2080. Results show that high CO2 conditions amplify both local and non-local biogeophysical effects of Amazon deforestation. Under high CO2 conditions, deforestation exacerbates warming within deforested regions and intensifies atmospheric circulation across South America, leading to aridification in non-deforested regions, such as eastern Brazil. These remote effects increase the risk of forest degradation and reduce carbon sequestration capacity. Our findings highlight that, without CO2 mitigation, Amazon deforestation may trigger more severe climatic consequences.