Understanding aerosol–climate–ecosystem interactions and the implications for terrestrial carbon sink using the Community Earth System Model

Abstract

Anthropogenic aerosols exert significant effects on the terrestrial ecosystem carbon cycle by causing climate change and altering surface hydrological conditions through radiation and cloud interaction, but such aerosol–climate–ecosystem interactions are difficult to quantify using currently available observations. Here, we used the Community Earth System Model (CESM, version 2.1.3) to quantify the effects of anthropogenic aerosols on terrestrial ecosystem carbon fluxes during the period from 1980 to 2014. The results found that the response of temperature and radiation to anthropogenic aerosols in different regions shows considerable variability in the CESM. Anthropogenic aerosols caused a 0.26 Pg C (0.43%) reduction in cumulative net biome production (NBP) during the period 1980-2014. In Southeast China (SEC) and East United States (EUS), anthropogenic aerosols caused a net reduction in NBP of 0.27 and 0.09 Pg C, respectively. In India (IND) and Europe (EUR), anthropogenic aerosols caused an increase of NBP by 0.07 and 0.14 Pg C, respectively. In addition, the decrease of the carbon sink was mainly dominated by changes in TER and others (40.6%), and the increase of the carbon sink was mainly dominated by changes in gross primary production (GPP) (38.9%). We also found that temperature is the dominant climate variable controlling the carbon cycle with a relative contribution of about 38%. Finally, the carbon flux response at the global scale is significantly lower than at the regional scale, which in turn highlights the importance of the assessment of the regional carbon cycle.