地球温暖化に伴い世界的なメタン濃度が上昇(Global methane levels continue rising as planet heats up)

2025-09-03 バーミンガム大学

バーミンガム大学とフローニンゲン大学の研究によると、大気中のメタン濃度は依然として上昇を続けており、気候変動を加速させている。研究は1990~2023年の164か国・120業種を対象に分析し、国際貿易が世界のメタン排出の約30%を占めることを突き止めた。特に急速な工業化と人口増加が進むアジアや太平洋地域が最大の排出源となっている。メタンはCO2よりも温室効果が強く、短期的に地球温暖化を大きく推進するため、その増加は国際的な気候対策に深刻な影響を及ぼす。本研究はNature Communicationsに掲載され、これまでで最も包括的なメタン排出データを提示し、経済活動や貿易構造が排出動向に直結していることを明確にした。結果は、排出削減のためには地域経済や産業構造の転換を含む国際的な協調が不可欠であることを示している。

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1990-2023年の地球規模メタンフットプリントの成長と駆動要因 Global methane footprints growth and drivers 1990-2023

Yuli Shan,Kailan Tian,Ruoqi Li,Yuru Guan,Jiamin Ou,Dabo Guan & Klaus Hubacek
Nature Communications  Published:03 September 2025
DOI:https://doi.org/10.1038/s41467-025-63383-5

地球温暖化に伴い世界的なメタン濃度が上昇(Global methane levels continue rising as planet heats up)

Abstract

Methane has been identified as the second-largest contributor to climate change, accounting for approximately 30% of global warming. Countries have established targets and are implementing various measures to curb methane emissions. However, our understanding of the trends in methane emissions and their drivers remains limited, particularly from a consumption perspective (i.e. accounting for all emissions along the entire global supply chain). This study investigates the most recent dynamics of methane emissions across 120 sectors from both production and consumption viewpoints in 164 countries. It also discusses the status of decoupling of production- and consumption-based methane emissions from economic growth. Our results indicate that there is no foreseeable slowdown in the momentum of global methane emissions growth. Only a few developed countries have managed to reduce both production- and consumption-based emissions while maintaining economic growth (i.e., strong decoupling) during the observed period (1990-2023). Global trade accounts for approximately 30% of global methane emissions, but major trade patterns are shifting from North-North and North-South to South-South countries, reflecting the increasing participating of developing countries in global supply chains. The study further reveals the changing drivers of global methane emissions from 1998 to 2023 in five-year intervals. It identifies that the reduction in emission coefficient (i.e., emissions per unit of output), driven by advancements in improved energy efficiency and cleaner production technologies, is the main determinant for reducing emissions over the observation period, partly offsetting the increasing effects from growth of final demand. Changes in demand structure have played a considerable role in the increase of emissions since 2008. This study enhances our understanding of the changes and drivers of methane emissions and supports countries in incorporating methane emissions into their climate mitigation strategies.

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