Li Junjie, Yuan Junji, Ciais Philippe, Kang Hojeong, Freeman Chris, Huang Yuanyuan, Dong Yanhong, Liu Deyan, Li Ye, Ding Weixin
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China.
University of Chinese Academy of Sciences, Beijing, China.
Nat Ecol Evol. 2025 Jul 22. doi: 10.1038/s41559-025-02809-1.
Terrestrial carbon (C) sink has long been recognized as trending upwards, yet its recent slowdown raises concerns about accelerating climate change. Variations in wetland C sequestration are hypothesized to play a key role in this shift. Here we mapped annual water levels in global wetlands from 2000 to 2020 using 2,295 field-based measurements and predicted the spatiotemporal pattern of wetland net ecosystem production (NEP) in conjunction with other environmental factors. By compiling 934 in situ observations, we estimated a global mean wetland NEP of 56.4 (44.0‒68.8) gC m yr. Integrating the NEP dataset with environmental datasets and machine-learning models, we estimated the mean annual global wetland C sequestration between 2000 and 2020 to be 1,004 (961‒1,047) TgC, 70% of which originated from tropical wetlands. We observed a decline in global wetland C sinks until 2005, followed by an increase thereafter. Overall, wetland C sequestration was roughly stable during 2000‒2020, as gains in northern mid-to-high latitudes were fully overwhelmed by declines in the tropics and southern mid-to-high latitudes. Our findings highlight hydrological change as a dominant driver of increasing regional variability in wetland C sinks, while intensifying hydrological extremes under climate change may undermine the resilience of wetland C sinks and the ecosystem services they support.
陆地碳汇长期以来一直呈上升趋势，但近期的放缓引发了人们对气候变化加速的担忧。湿地碳固存的变化被认为在这一转变中起关键作用。在此，我们利用2295个实地测量数据绘制了2000年至2020年全球湿地的年水位图，并结合其他环境因素预测了湿地净生态系统生产（NEP）的时空格局。通过汇总934个原位观测数据，我们估计全球湿地NEP的平均值为56.4（44.0 - 68.8）gC m⁻² yr⁻¹。将NEP数据集与环境数据集及机器学习模型相结合，我们估计2000年至2020年全球湿地年平均碳固存为1004（961 - 1047）TgC，其中70%来自热带湿地。我们观察到全球湿地碳汇在2005年之前下降，之后上升。总体而言，2000 - 2020年期间湿地碳固存大致稳定，因为北半球中高纬度地区的增加被热带地区和南半球中高纬度地区的下降完全抵消。我们的研究结果突出了水文变化是湿地碳汇区域变异性增加的主要驱动因素，而气候变化下极端水文事件的加剧可能会削弱湿地碳汇及其所支持的生态系统服务的恢复力。
