MERGE SP: Plant BVOCs Regulated Feedbacks to the Changing Climate

Biogenic volatile organic compounds (BVOCs), mainly emitted from plants, are highly reactive hydrocarbons and play significant roles in atmospheric chemistry. BVOCs influence the climate system through lengthening the lifetime of methane (a potent greenhouse gas), forming aerosols and cloud, and influencing surface ozone concentrations. Warming alone is expected to elevate BVOC emissions, but also alter vegetation composition. My recent study1 through coupling LPJ-GUESS modelled BVOCs with global chemistry transport model, TM5, shows that future BVOC impacts on atmospheric aerosols are closely linked to warming-induced vegetation changes in the high latitudes. This study further highlights the importance of warming-induced vegetation changes on shaping BVOC feedbacks on regional secondary organic aerosol (SOA) formations. One of the limitations of the study is that the studied compounds are restricted to two dominant compound groups: isoprene and monoterpenes, without considering the dynamics of plant emissions of many other volatile compounds and their contributions to atmospheric chemistry. Furthermore, to account for the impacts of BVOC on the changing climate, we need to run the fully-coupled earth system model, such as EC-Earth. The current limitation in EC-Earth is that plant-emitted BVOCs (simulated LPJ-GUESS) are not coupled with the atmospheric chemistry part in EC-Earth. Instead, a global dataset, disconnected from vegetation status, was read in to quantify potential impacts from BVOCs, meaning large uncertainties in quantified BVOC impacts on our climate system.
To fill this gap, this project aims to fully couple LPJ-GUESS modelled plant BVOC emissions with atmospheric processes in the upcoming version of EC-Earth 4. More specifically, the major aims are to: (1) extend LPJ-GUESS modelled volatile compounds till full spectrum of compound species (20 functional groups and approx. 150 compound species); (2) develop a flexible framework where the compound species can be easily mapped to different aerosol schemes; (3) assess BVOC impacts on the modelled aerosol and cloud radiative forcing after explicitly linked to vegetation dynamics and plant photosynthesis.