Fluctuating "soil CO2-lake" is key for understanding global climate change

The increasing atmospheric CO2 concentration has long been recognized as the main driver of global warming since the industrial revolution. CO2 removal technologies have been proposed to mitigate anthropogenic CO2 emissions.1 Much attention has been paid to soil CO2 emissions primarily because of their major contribution to increasing atmospheric CO2 concentration.2 However, the impact of pedospheric CO2 on the terrestrial C cycle and related global climate change goes far beyond this. For instance, mineral and/or alkali-induced CO2 trapping can often occur in soil, and soil and its CO2 concentration can directly regulate the land surface heat balance by enhancing heat retention,3 but the contributions of these pedospheric processes to climate change mitigation have not been fully understood. Combining atmospheric and pedospheric CO2 can reflect both the heat absorption in the atmosphere and the heat retention within the soil, providing a comprehensive understanding of the C cycle and contributing to the development of sustainable solutions to mitigate climate change.

Here, we estimate the standing amount of the soil CO2 pool and its turnover rate in terrestrial lands. Then, the concept of “soil CO2-lake” is introduced, and its crucial roles in C cycling and climate change mitigation are illustrated. Finally, the contribution of the “soil CO2-lake” concept to global climate change studies is discussed.