An ignored key link in greenhouse effect: Soil and soil CO2 slow heat loss

Abstract

The ever-increasing atmospheric CO 2 concentration is a key driver of modern global warming. However, the low heat capacity of atmosphere and strong convection processes in the troposphere both limit heat retention. Given the higher heat capacity and CO 2 concentration in soil compared to the atmosphere, the direct contributions of soil to the greenhouse effect may be significant. By experimentally manipulating CO 2 concentrations both in the soil and the atmosphere, we demonstrated that the soil-retained heat and the slower soil heat transmission decrease the amount of heat energy leaking from the earth. Furthermore, the soil air temperature was affected by soil CO 2 concentration, with the highest value recorded at 7500 ppm CO 2. This study indicates that soil and soil CO 2 , together with atmospheric CO 2 , play a crucial role in the greenhouse effect. The spatial and temporal heterogeneity of soils and soil CO 2 should be further investigated, given their potentially significant influence on global climate change.

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

“… 2 However, the impact of pedospheric CO 2 on the terrestrial C cycle and related global climate change goes far beyond this. For instance, mineral and/or alkali-induced CO 2 trapping can often occur in soil, and soil and its CO 2 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 CO 2 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.…”

“…Additionally, the soil CO 2 -lake directly influences the soil heat balance. Soil CO 2 nonlinearly increases soil air temperature when its concentration is below 7,500 ppm, but it decreases soil air temperature when its concentration reaches 16,900 ppm 3 ; such a CO 2 -concentration-mediated negative feedback regulation of temperature maintains a relatively stable soil heat balance and thus contributes to the greenhouse effect. Furthermore, such a mild increase in soil temperature will stimulate belowground biological activities and enhance silicate weathering.…”