大気浄化政策が思わぬ影響を与え、湿地のメタン排出を増加させる(Clean air policies having unintended impact driving up wetland methane emissions)

2025-02-06 バーミンガム大学

＜関連情報＞

• https://www.birmingham.ac.uk/news/2025/clean-air-policies-having-unintended-impact-driving-up-wetland-methane-emissions
• https://www.science.org/doi/10.1126/sciadv.adn1056

大気中の硫酸塩沈着量の減少とCO2濃度の上昇が、将来の湿地のCH4排出を刺激する大きな役割 The large role of declining atmospheric sulfate deposition and rising CO2 concentrations in stimulating future wetland CH4 emissions

Lu Shen, Shushi Peng, Zhen Zhang, Chuan Tong, […], and Vincent Gauci
Science Advances  Published:5 Feb 2025

Abstract

Existing projections of wetland methane emissions usually neglect feedbacks from global biogeochemical cycles. Using data-driven approaches, we estimate wetland methane emissions from 2000 to 2100, considering effects of meteorological changes and biogeochemical feedbacks from atmospheric sulfate deposition and CO₂ fertilization. In low-CO₂ scenarios (1.5° and 2°C warming pathways), the suppressive effect of sulfate deposition on wetland methane emissions largely diminishes by 2100 due to clean air policies, with resulting emission increases (7 ± 2 Tg a⁻¹) being 35 and 22% of total wetland emission changes. In mid-CO₂ scenarios (2.4° to 3.6°C warming pathways), sulfate deposition changes modestly, and CO₂ fertilization contributes >30% of wetland emission increases. Across all scenarios, biogeochemical feedbacks can stimulate 30 to 45% of future wetland emission rises. Under 1.5° and 2°C pathways, wetland methane emissions will likely increase by 20 to 34 Tg a⁻¹ by 2100, representing 8 to 15% of the allowable space for anthropogenic methane emissions, a factor not yet considered by current assessments.