Abstract. Soil organic carbon sequestration (SOCseq) is considered the most attractive carbon capture technology to partially mitigate climate change. However, there is conflicting evidence regarding the potential of SOCseq. The additional storage potential on existing global cropland is missing. SOCseq is region-specific and conditioned by management but most global estimates use fixed accumulation rates or time frames. Here, we show how the SOC storage potential and its steady state varies globally depending on climate, land use and soil. Using 83,416 soil observations, we developed a quantile regression neural network that quantifies the SOC variation within soils with similar characteristics. This allows us to identify similar areas that present higher SOC with the difference representing an additional storage potential. The estimated additional SOC storage potential of 29 to 67 Pg C in the topsoil of global croplands equates to only 2 to 5 years of emissions offsetting and 32 % of agriculture's 92 Pg historical carbon debt estimate due to conversion from natural ecosystems. Since SOC is temperature-dependent, this potential is likely to reduce by 18 % by 2040 due to climate change.

中文翻译：

---

全球农田的额外土壤有机碳储存潜力

摘要。土壤有机碳封存（SOCseq）被认为是部分缓解气候变化的最具吸引力的碳捕获技术。然而，关于 SOCseq 的潜力存在相互矛盾的证据。现有全球农田的额外储存潜力缺失。SOCseq 是特定于区域的，并由管理层决定，但大多数全球估计使用固定的累积率或时间框架。在这里，我们展示了 SOC 储存潜力及其稳定状态如何根据气候、土地利用和土壤在全球范围内变化。使用 83,416 份土壤观测，我们开发了一个分位数回归神经网络，可以量化具有相似特征的土壤中的 SOC 变化。这使我们能够识别出具有更高 SOC 的相似区域，其差异代表了额外的存储潜力。全球农田表土中 29 至 67 Pg C 的估计额外 SOC 储存潜力仅相当于 2 至 5 年的排放抵消和农业 92 Pg 历史碳债务估计值的 32%，这是由于从自然生态系统的转化。由于 SOC 与温度有关，到 2040 年，由于气候变化，这种潜力可能会降低 18%。