Major global change factors, including carbon dioxide (CO₂) fertilization, warming, change in precipitation, nitrogen deposition, and land-use change have the potential to significantly affect future stocks of soil organic carbon (SOC). These factors, individually or by interacting with each other, can also trigger positive or negative feedback to the processes affecting the rate of SOC formation or loss. Despite rapid progress in the understanding of carbon (C) cycling processes in the last few decades, much uncertainty remains in our ability to precisely forecast potential changes in SOC stocks in the rapidly changing future world. Stable C isotopes have been extensively used in natural observational studies as well as in laboratory and field experiments that manipulate CO₂ concentration, temperature, moisture, nitrogen fertilization, and vegetation type to understand the complex interactions and feedbacks that result from changing climate, plants and their herbivores, as well as soil microorganisms. Newly developed tools such as compound-specific isotope analysis, nano-SIMS (secondary ion mass spectroscopy), and stable isotope probing (SIP) permit isotope tracing in a specific ecosystem pool into specific C compounds and processes, thus providing in-depth insights into many processes affecting C biogeochemistry. The recent availability of affordable and reliable field-deployable optical isotope monitoring devices has provided researchers with a new set of tools for continuously tracking the ¹³C-CO₂ fluxes at the ecosystem level, enabling deeper insights into C biogeochemistry under changing environmental conditions. Despite these great strides, there is a scarcity of review studies that have comprehensively examined the use of C isotopes in studying SOC responses under global change factors. This review highlights recent progress in understanding the effect of major global change factors on SOC fluxes and stocks using selected examples covering scales from plant rhizospheres to geographic regions. Moreover, we discuss the strengths and limitations of current approaches and recent scientific advancements to highlight the new prospects evolving from the exceptional temporal and spatial resolution of stable isotope analysis in studying how global change affects SOC. Finally, we suggest that studies using stable C isotopes are well-poised to focus on identifying how dominant SOC cycling processes respond to environment-specific limiting factors and any thresholds and tipping points that define those relationships.

主要的全球变化因素，包括二氧化碳 (CO ₂ ) 施肥、变暖、降水变化、氮沉降和土地利用变化，可能会显着影响未来的土壤有机碳 (SOC) 储量。这些因素，单独地或通过彼此相互作用，也可以触发对影响 SOC 形成或损失速率的过程的正反馈或负反馈。尽管在过去几十年中对碳 (C) 循环过程的理解取得了快速进展，但我们在快速变化的未来世界中准确预测 SOC 储量潜在变化的能力仍然存在很大不确定性。稳定的 C 同位素已广泛用于自然观察研究以及操纵 CO _{2的实验室和现场实验}浓度、温度、水分、氮肥和植被类型，以了解气候变化、植物及其食草动物以及土壤微生物引起的复杂相互作用和反馈。新开发的工具，如化合物特异性同位素分析、nano-SIMS（二次离子质谱）和稳定同位素探测 (SIP)，允许将特定生态系统池中的同位素追踪到特定的 C 化合物和过程，从而提供深入了解许多影响 C 生物地球化学的过程。最近出现的经济实惠且可靠的可现场部署的光学同位素监测设备为研究人员提供了一套用于连续跟踪¹³ C-CO _{2的新工具}生态系统水平的通量，从而能够更深入地了解不断变化的环境条件下的 C 生物地球化学。尽管取得了这些巨大进步，但很少有综述研究全面检查了 C 同位素在研究全球变化因素下的 SOC 响应中的用途。这篇综述强调了最近在理解主要全球变化因素对 SOC 通量和库的影响方面取得的进展，使用涵盖从植物根际到地理区域的选定示例。此外，我们讨论了当前方法的优势和局限性以及最近的科学进步，以突出在研究全球变化如何影响 SOC 中稳定同位素分析的特殊时间和空间分辨率所带来的新前景。最后，