Various responses of global heterotrophic respiration to variations in soil moisture and temperature enhance the positive feedback on atmospheric warming

The ratio of soil heterotrophic respiration to total soil respiration (Rh/Rs) is critical for soil carbon pool stability and atmosphere-biosphere exchanges, yet its spatiotemporal dynamics and responses to environmental drivers remain poorly constrained. Here, we estimate global soil and heterotrophic respiration by integrating ground observations with machine learning models. From 1980 to 2022, annual increases reached 0.76 and 0.54 g C m⁻² yr⁻² for soil and heterotrophic respiration, respectively. Globally, Rh/Rs averaged 61.30 ± 0.54% with a decadal rise of 0.13%. Rising soil temperature enhances Rh/Rs, while soil moisture suppresses it, exhibiting stronger global-scale influence. Temperature dominates Rh/Rs regulation in forests and shrublands, whereas moisture controls this ratio in grasslands and croplands. These findings elucidate ecosystem-specific mechanisms governing Rh/Rs dynamics, advancing predictions of soil carbon-climate feedbacks essential for carbon neutrality strategies. Both soil heterotrophic respiration and soil respiration increased globally during 1980-2022 and rising temperature enhanced the proportion of heterotrophic respiration to soil respiration, according to analysis of ground observation data combined with machine learning models.