Department of Earth and Environmental Science, School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China.
Department of Earth and Environmental Science, School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China.
Sci Total Environ. 2021 Dec 10;799:149247. doi: 10.1016/j.scitotenv.2021.149247. Epub 2021 Jul 23.
Soil carbon (SC) is a key component of the carbon cycle and plays an important role in climate change; however, quantitatively assessing SC dynamics at the regional scale remains challenging. Earth system model (ESM) that considers multiple environmental factors and spatial heterogeneity has become a powerful tool to explore carbon cycle-climate feedbacks, although the performance of the ESM is diverse and highly uncertain. Thus, identifying reliable ESMs is a prerequisite for better understanding the response of SC dynamics to human activity and climate change. The 16 ESMs that participated in the fifth phase of the Coupled Model Intercomparison Project (CMIP5) were employed to evaluate the skill performance of SC density simulation by comparison with reference data from the International Geosphere-Biosphere Programme Data and Information System (IGBP-DIS). Although ESMs generally reflect spatial patterns with lower SC in northwest China and higher SC in southeast China, 11 of 16 ESMs underestimated the SC in China, and 5 of 16 ESMs overestimated the SC density as most ESMs had large discrepancies in capturing the SC density in the northern high latitudes of China and the Qinghai-Tibet Plateau. According to a series of model performance statistics, SC simulated by Institute Pierre Simon Laplace (IPSL) Coupled Model had a close spatial pattern with IGBP-DIS and showed higher skills for SC predictions in China relative to other CMIP5 ESMs. The multimodel ensemble average obtained by IPSL family ESMs showed that SC density exhibited increasing trends under both the RCP4.5 scenario and RCP8.5 scenario. The SC density increased slowly under RCP8.5 compared with that under RCP4.5 and even displayed a decreasing trend in the late 21st century. The findings of this study can provide a reference for identifying the shortcomings of SC predictions in China and guide SC parameterization improvement in ESMs.
土壤碳（SC）是碳循环的关键组成部分，在气候变化中起着重要作用；然而，定量评估区域尺度上的 SC 动态仍然具有挑战性。地球系统模型（ESM）考虑了多种环境因素和空间异质性，已成为探索碳循环-气候反馈的有力工具，尽管 ESM 的性能差异很大且高度不确定。因此，确定可靠的 ESM 是更好地了解 SC 动态对人类活动和气候变化响应的前提。本研究利用参与第五次耦合模式比较计划（CMIP5）的 16 个 ESM 来评估 SC 密度模拟的技能表现，将其与国际地圈生物圈计划数据和信息系统（IGBP-DIS）的参考数据进行比较。尽管 ESM 通常反映了空间格局，即中国西北部的 SC 较低，东南部的 SC 较高，但 16 个 ESM 中有 11 个低估了中国的 SC，16 个 ESM 中有 5 个高估了 SC 密度，因为大多数 ESM 在捕捉中国北方高纬度和青藏高原的 SC 密度方面存在较大差异。根据一系列模型性能统计，IPSL 耦合模型模拟的 SC 与 IGBP-DIS 的空间格局较为接近，且相对于其他 CMIP5 ESM，对中国 SC 的预测具有更高的技能。由 IPSL 家族 ESM 获得的多模型集合平均值表明，在 RCP4.5 情景和 RCP8.5 情景下，SC 密度均呈增加趋势。与 RCP4.5 相比，RCP8.5 下 SC 密度增加缓慢，甚至在 21 世纪后期呈现下降趋势。本研究结果可为识别中国 SC 预测的不足提供参考，并指导 ESM 中 SC 参数化的改进。
