What Controls Recent Changes in the Global Carbon-climate Feedback Process?

C. Park and S. Jeong

Seoul National University, Seoul, South Korea; 8210-8902-8984, E-mail: crplove@snu.ac.kr

The global atmospheric CO₂ growth rate is determined by reflecting the net effect of emissions and uptake from anthropogenic and natural carbon sources. Therefore, an evaluation of the global CO₂ growth rate should be preceded to understand the global carbon-climate process. In this study, the long-term changes in the global CO₂ growth rate for the period 1991-2020 were analyzed by using various observations from 42 global sites and model simulations to evaluate the recent changes in the global carbon-climate feedback process. Results showed that the annual CO₂ growth rate is recently increasing by the magnitude of 0.046 ppm yr^-2. A comprehensive assessment of the contribution of carbon cycle components to the observed atmospheric CO₂ growth rate changes reveals that strengthening the increasing atmospheric CO₂ growth rate is related to the weakening terrestrial carbon absorption in the recent decade. Weakening terrestrial carbon uptake is mainly related to a slowdown in Net Primary Productivity (NPP; 0.087 Pg C yr^-1). Overall, this study suggests land ecosystems could not sufficiently play a role in offsetting anthropogenic carbon emissions due to significant climatic warming.

This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT) (No. NRF-2019R1A2C3002868).

Figure 1. Time series of global annual CO2 growth rate (right) calculated from 42 global observation sites (left).