Abstract Soils hold vast amounts of organic carbon and play a pivotal role in the global carbon cycle. The turnover time ( τ ) and temperature sensitivity of the soil carbon cycle—commonly expressed as Q 10 —are critical parameters for projecting climate–carbon feedbacks under climate change. However, the temperature dependency of soil Q 10 remains controversial, with reported values varying widely across studies. Here, we synthesize global datasets of soil organic carbon stocks and heterotrophic respiration to evaluate turnover time and Q 10 . Our analysis of harmonized global maps shows that the soil carbon turnover time decreases with increasing temperature and the soil carbon-weighted mean τ for the 0–100 cm layer is 83.3 years. Analysis of the temperature dependence of turnover time indicates that the emergent temperature dependency of Q 10 is weak, with limited divergence across climate zones. These findings suggest that, despite large carbon stocks, the temperature-driven vulnerability of soil carbon in cold regions may be lower than previously assumed. The emergent turnover time and temperature sensitivity derived in this study provide new constraints for Earth system models.
Hashimoto et al. (Tue,) studied this question.