人間活動が小規模水域の温室効果ガス排出を増大させることを解明（Human Activities Intensify Small Water Bodies’ Greenhouse Gas Emissions）

2026-06-22 中国科学院（CAS）

＜関連情報＞

• https://english.cas.cn/newsroom/research-news/202606/t20260622_1174452.shtml
• https://www.pnas.org/doi/10.1073/pnas.2537678123

地球上の小規模水域からの気候変動に起因する温室効果ガス排出量の人為的増幅 Human amplification of climate-induced greenhouse gas emissions from global small water bodies

Xuliang Zhuang xlzhuang@rcees.ac.cn, Xiaoxuan Liu, Shengjun Xu, +6 , and Shilong Piao
Proceedings of the National Academy of Sciences  Published:May 18, 2026
DOI:https://doi.org/10.1073/pnas.2537678123

Significance

Small water bodies (SWBs) are critical but often overlooked components of the global carbon cycle. We demonstrate that human activities, particularly agricultural nutrient loading and urbanization, amplify climate-driven greenhouse gas emissions from these systems, causing them to emit disproportionately high amounts of methane and carbon dioxide relative to their small surface area. By developing a high-resolution global inventory that explicitly includes methane ebullition (bubbles), we reveal that anthropogenic pressures transform SWBs from passive responders to active amplifiers of warming. Crucially, our projections under future climate scenarios show that sustainable nutrient management could significantly mitigate emission increases. These findings highlight the urgent need to integrate aquatic management into global climate mitigation strategies.

Abstract

Human activities amplify climate-induced greenhouse gas emissions from small water bodies (SWBs), creating critical but unquantified feedback in the global carbon cycle. Here, by training machine learning models on 470 field observations and upscaling to a global database of 3.28 million water bodies, we quantify this human amplification, which drives SWBs to emit 84.5 Tg CO₂ y⁻¹ and 11.0 Tg CH₄ y⁻¹, a disproportionate share of total inland water emissions (15% of CO₂ and 28% of CH₄) from only 6% of Earth’s surface area. This amplification is primarily fueled by agricultural nutrient loading and land use intensity, which elevate CH₄ fluxes in agricultural catchments five times higher than those in forested systems. Future projections show this synergy will increase emissions by up to 30% (CO₂) and 14% (CH₄) by 2100 under SSP5-8.5, whereas sustainable pathways (SSP1-2.6) could mitigate this emission acceleration through nutrient mitigation efforts, a largely neglected feedback process in current climate change assessments.