Drying and rewetting cycles increase CO₂ emission from soils

2025.01.23

Global-warming-induced alterations in precipitation patterns can influence carbon dioxide (CO₂) emission from soils. A new study, conducted by the Nuclear Science and Engineering Center, in collaboration with Niigata University and Kyushu University, reveals that soil drying and rewetting cycles largely increase CO₂ emission from soils.

Increasing the atmospheric CO₂ concentration causes global warming and alters the global water cycling and precipitation patterns. Extreme heavy rainfall and extended drought are often observed around the world, which intensify soil drying and rewetting cycles and influence the decomposition of soil organic carbon and consequently the CO₂ emission from soils. Since the CO₂ emission from the world’s soils is estimated to be about 5 times the amount of CO₂ emission from human activities, even a small change in CO₂ emission from soils could significantly impact the Earth’s climate system. The research team studied overall trends in the effects of soil drying and rewetting cycles on the CO₂ emission by conducting an 84-day laboratory incubation experiment using 10 Japanese forest and pastureland soils. They found a 1.3 to 3.7-fold increase in CO₂ emission due to drying and rewetting cycles across all soils. Furthermore, they analyzed relations between the increasing magnitude of CO₂ emission and soil properties, and suggested that the increase in CO₂ emission occurred mainly through destructions of microbial cells and organo-mineral complexes during drying and rewetting cycles. The findings of this study have important implications for understanding the climate–carbon cycle feedback and for improving the ability to predict the future of Earth’s climate.

The results of this study have been published in “SOIL,” an international scientific journal issued by the European Geoscience Union, on January 16, 2025. Article information: https://soil.copernicus.org/articles/11/35/2025/

JAEA HP Press release (Japanese only)