Biochar-Induced Soil Property Changes May Reduce Temperature and Precipitation Extremes: Insights from Earth System Model Experiments

Abstract. Biochar has been proposed as a promising soil amendment for climate change mitigation, owing to its capacity to sequester carbon and alter soil physical properties. This study investigates the potential influence of biochar-induced changes in soil hydrological and thermal properties on future climate, with a focus on extreme climate events. We implemented a series of biochar addition scenarios (ranging from 5 to 150 t/ha) into the Max Planck Institute Earth System Model (MPI-ESM), modifying eight soil physical variables via pedo-transfer functions to investigate their impacts on climate in the near future (2040–2049) under the CMIP6 framework.

Our results show that while biochar-induced soil property changes produced minimal global effects on temperature and precipitation, they led to more structured and consistent responses in climate extremes over land. In particular, the addition of biochar reduced temperature extremes – especially nighttime minimum temperatures (TNn) – across cold regions such as Eastern Europe, the Russian Arctic, and West Siberia. Contrary to our initial hypothesis, these effects were not driven by enhanced latent heat flux but rather by increased humidity and cloud cover that altered surface energy balance via sensible heat redistribution. Precipitation extremes also responded to biochar addition, with a consistent decrease in extreme rainfall (Rx1day) over land. However, changes in consecutive dry days (CDD) were more region-specific, with increases observed in arid and coastal regions such as the Arabian Peninsula and Central Australia, indicating heightened drought risks in already vulnerable zones.

These findings suggest that although biochar’s direct modifications are localized, its indirect effects on climate extremes can extend across sensitive regions through land-atmosphere interactions. Our study highlights the importance of integrating both biogeophysical and biogeochemical pathways in Earth system models to better evaluate biochar's climate mitigation potential.