High-resolution global map (100 m) of soil organic carbon reveals critical ecosystems for carbon storage

Abstract. Uncertainty in soil organic carbon (SOC) stocks and fluxes resulting from land disturbance and recovery processes remains a significant challenge for closing the global carbon budget, accurately quantifying the land carbon sink, and assessing restoration carbon credits in nature-based climate solutions. To address this, we develop a spatially resolved SOC estimate at a 1-hectare resolution globally, aligning with the scale of land-use disturbances, to significantly improve carbon accounting accuracy and reduce uncertainty across multiple use cases. We compile and harmonize a global SOC inventory, incorporating 84,880 (30 cm depth) and 44,304 (100 cm depth) measurements. Additionally, we identify high-resolution remote sensing and in situ spatial covariates to map SOC using advanced, biome-specific machine learning algorithms.

We measure global SOC stocks of 1,049 Pg C at 30 cm and 2,822 Pg C at 100 cm. Our results reveal a 31 % increase in SOC at 30 cm and a 45 % increase at 100 cm compared to the average of prior estimates. Our model indicates that peatlands including peat-in-soil mosaics store 146 Pg C at 30 cm depth and 344 Pg C at 100 cm depth, accounting for 14 % and 12 % of global SOC stocks respectively. Mangrove ecosystems have some of the highest soil carbon densities among global biomes, and hold 1.3 Pg C at 30 cm depth and 4.4 Pg C at 100 cm depth, despite covering a relatively small global area. We find that biome-level SOC estimates strongly depend on biome area and its changes over time. Our analysis indicates that annual wildfire dynamics and shifts in agricultural land can influence SOC by 132 Pg C and 140 Pg C at 30 cm, and by 345 Pg C and 368 Pg C at 100 cm, representing approximately 13 % of the global stocks. The SOC maps from this study, including pixel-level 95 % confidence intervals to quantify model uncertainty, are hosted on a Zenodo repository. These data will be made publicly available upon publication to support large-scale carbon accounting and integration by the scientific and policy communities. The repository is accessible through the reviewer link (Creze et al., 2025): https://zenodo.org/records/15391412?preview=1&token=eyJhbGciOiJIUzUxMiJ9.eyJpZCI6ImNjZjk2YTM5LTQyM2ItNDZiMC1iY2RlLTg0ZTA1ZjU1MDZjNSIsImRhdGEiOnt9LCJyYW5kb20iOiIxMjc1YmI0OTZhOTNiMmQyNTIxYjYyNzRiM2ZlZjBmMyJ9.M5VUSwR4GkeoKV1Kno1v3b3qLUAzErns1Zh6u0om2HhVDrnxcjKJS3WCOVAoJlSyxt-5Kbc809apXwYmAnMqyQ.