Vast ecosystem disturbance in a warming climate may jeopardize our climate goal of reducing CO: a case study for megafires in the Australian 'black summer'.

A warming climate is one of the most important driving forces of intensified wildfires globally. The unprecedented wildfires broke out in the Australian 'Black Summer' (November 2019-February 2020), which released massive heat, gases, and particles into the atmosphere. The total carbon dioxide (CO) emissions from wildfires were estimated at ∼963 million tons by using a top-down approach based on direct satellite measurements of CO and fire radiative power. The fire emissions have led to an approximately 50-80 folds increase in total CO emission in Australia compared with the similar seasons of 2014-2019. The excess CO from wildfires has offset almost half of the global anthropogenic CO emission reductions due to the Corona Virus Disease 2019 in 2020. When the wildfires were intense in December 2019, they caused a 1.48 watts per square meter additional positive radiative forcing above the monthly average in Australia and the vicinity. Our findings demonstrate that vast ecosystem disturbance in a warming climate can strongly influence the global carbon cycle and hamper our climate goal of reducing CO.