Understanding the impacts of inter-model difference in atmospheric CO2 concentration on terrestrial vegetation

The increasing of atmospheric CO₂ concentration due to human activities accelerates a warming rate and causes extreme climate events. The atmospheric-terrestrial biosphere carbon cycle is important for achieving the Paris agreement warming target and carbon neutrality with net zero emission. To understand the ecosystem carbon cycle, the Earth system model (ESM) is developed. However, there is a large inter-model uncertainty among ESMs thus reducing this uncertainty through understanding the relationship between atmospheric CO₂ concentration and the terrestrial biosphere carbon cycle is important for reliable climate projection. Here, we investigate the impacts of inter-model differences in CO₂ concentration over the East Asia on terrestrial carbon cycle using multi-ESMs. There is a larger uncertainty CO₂ concentration in ESMs during historical period (1950-2014). To investigate impact of inter-model difference of CO₂ concentration in ESMs on terrestrial vegetation in East Asia, we analyze emission-driven historical simulation in CMIP6 by classifying ESMs into two groups based on the averaged CO₂ concentration in East Asia. The results show that inter-model difference of CO₂ concentration in East Asia is associated with the carbon fertilization effect. ESMs with high CO₂ concentration tend to simulate promoted vegetation activity. Furthermore, we analyze the relationship between CO₂ concentration, terrestrial biosphere, and climate factors.