Two decades of improved wetland carbon sequestration in northern mid-to-high latitudes are offset by tropical and southern declines

[Geoengineering News]

https://www.nature.com/articles/s41559-025-02809-1

Authors

Junjie Li, Junji Yuan, Philippe Ciais, Hojeong Kang, Chris Freeman, Yuanyuan Huang, Yanhong Dong, Deyan Liu, Ye Li & Weixin Ding 

22 July 2025

Abstract

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−2 yr−1. 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.

Source: Nature Ecology & Evolution

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