Tuesday 17 Apr 2018: Global fire air pollution weakens terrestrial ecosystem productivity
Xu Yue - Institute of Atmospheric Physics
Fire is an important disturbance to the terrestrial carbon budget. Every year, global fires directly emit 2-3 Pg (=1015 g) carbon into the atmosphere. In addition to the carbon emissions, fire plumes also generate short-lived climate pollutants, including ozone (O3) and aerosols, which may worsen air quality in the local and downwind regions. Increases in O3 and aerosols have strongly contrasting impacts on plant productivity. O3 is phytotoxic and reduces plant photosynthesis, while aerosol pollution may promote photosynthesis by enhancing diffuse radiation. Here, I will present a recent study on the net effects of fire O3 and aerosols on land ecosystem productivity, in combination of various models and multiple measurements. The results show strong dampening effect of fire pollution to global gross primary productivity (GPP), because O3 damaging is usually much higher than the aerosol diffuse fertilization. It suggests that fires weaken land carbon sink indirectly through the emissions of air pollution.