Difficulties in Reducing Atmospheric CO 2 Concentrations during the Modern Warm Period

Abstract

According to the IPCC, when anthropogenic CO 2 emissions increase, the atmospheric CO 2 concentration increases, and the temperature increases due to the greenhouse effect of CO 2 . In the mechanism derived in our recent papers, the rise in temperature during the modern warm period increases CO 2 emissions due to an increase in soil respiration ( Rs control process ). The CO 2 emitted due to an increase in temperature can be considered thermally induced CO 2 . Therefore, although there is a correlation between temperature and CO 2 concentration, there is a temperature-leading time lag due to the Rs control process. In this work, we analyzed the relationships between temperature changes and CO 2 concentration changes in detail. As a result, we found that even if anthropogenic CO 2 decreases, it is difficult to reduce the atmospheric CO 2 concentration because of the large Rs control process during the modern warm period. One of the main reasons is that the Rs control process in midlatitude forests is significantly affected by temperature changes, which also means that the increase in anthropogenic CO 2 since the Industrial Revolution has had only a small effect on the change in global CO 2 concentrations.