Impacts of heterogeneous CO2 on water and carbon fluxes across the global land surface

Abstract

Over the recent decades, the increase of atmospheric carbon dioxide (CO₂) concentration has caused large effects on the earth system. However, few studies have paid attention to the effects of heterogeneity of CO₂ on the biosphere and the hydrosphere. Using a coupled diagnostic biophysical model (PML-V2) and comparing three heterogeneous CO₂ datasets (GOSAT, CMIP6 and CarbonTracker) against a baseline homogeneous data (ESRL), this study investigated the effects of heterogeneous CO₂ on gross primary production (GPP), actual evapotranspiration (ET) and water use efficiency (WUE) across the global. The results show that among the three heterogeneity CO₂, CarbonTracker produced the highest CO₂ concentration and showed the largest difference in ET (−6% to 2%), GPP (−2% to 5%) and WUE (4% to 11%) compared to those from the baseline. The most effects of the CO₂ heterogeneity occurred in summer. Russia was identified as a vulnerable region with prominent decrease in GPP and an increase in ET due to CO₂ heterogeneity. An obvious increase in GPP and a decrease in ET appeared in the Amazon rainforest, the Congo rainforest, and eastern Asia. On global scale, the effects of the CO₂ heterogeneity on ET/GPP/WUE were not significant.