長期観測データの統合解析から 2022年までのメタン濃度の変動が明らかに～国環研と協力機関による日本独自の観測の貢献～

2025-07-07 国立環境研究所,気象庁気象研究所,獨協大学

＜関連情報＞

• https://www.nies.go.jp/whatsnew/2025/20250707/20250707.html
• https://progearthplanetsci.springeropen.com/articles/10.1186/s40645-025-00711-9

国立環境研究所と共同観測ネットワークによって観測された大気メタンの長期的および経年的変動 Long-term and interannual variations of atmospheric methane observed by the NIES and collaborative observation networks

Taku Umezawa,Yasunori Tohjima,Yukio Terao,Motoki Sasakawa,Astrid Müller,Tazu Saeki,Toshinobu Machida,Shin-Ichiro Nakaoka,Hideki Nara,Shohei Nomura,Masahide Nishihashi,Hitoshi Mukai,Matthias Max Frey,Isamu Morino,Hirofumi Ohyama,Yukio Yoshida,Jiye Zeng,Hibiki Noda,Makoto Saito,Tsuneo Matsunaga,Takafumi Sugita,Hiroshi Tanimoto,Yosuke Niwa,Akihiko Ito,… Hidekazu Matsueda
Progress in Earth and Planetary Science  Published:03 June 2025
DOI:https://doi.org/10.1186/s40645-025-00711-9

Abstract

Effective action for climate change mitigation requires an accurate understanding of global greenhouse gas budgets, including those of methane (CH₄). Atmospheric measurement data provide key constraints for estimating the magnitudes and distributions of sources and sinks and are utilized in atmospheric chemistry transport modeling studies. Long-term atmospheric measurement networks have revealed decadal, interannual, and seasonal variations in atmospheric CH₄. In 2020, a record-breaking annual CH₄ increase was recorded, but its cause is still unknown. This study analyzes atmospheric CH₄ variations using data from the National Institute for Environmental Studies (NIES) and its collaborative observation networks. Datasets from ground, mobile, and satellite platforms, employing diverse measurement techniques, confirmed past episodes, recent remarkable increases, and spatial distributions of atmospheric CH₄. Our data clearly showed a sustained CH₄ increase from 2020 to 2022, with the highest annual increase in 2021. The atmospheric CH₄ increase was pronounced in the northern mid-to-high latitudes in 2020, but the enhancement shifted south in 2021 and 2022. This study demonstrates the capability of observational data from the NIES and collaborative networks in accurately characterizing spatiotemporal variations in atmospheric CH₄ regularly, supporting the improvement of our estimates of the global CH₄ budget.