Nature Climate Change, Published online: 23 June 2026; doi:10.1038/s41558-026-02678-xSoil carbon is a critical component of the terrestrial carbon sink and is impacted by the total belowground carbon allocation (TBCA). This study uses a long-term multifactor grassland experiment to show that elevated temperature and CO2 increased the TBCA over time, modulated by drought and N addition.