Multi-observational estimation of regional and sectoral emission contributions to the persistent high growth rate of atmospheric CH4 for 2020-2022
(2025) In Atmospheric Chemistry and Physics 25(13). p.6757-6785- Abstract
Atmospheric methane (CH4) growth rates reached unprecedented values in the years 2020-2022. To identify the main drivers of this increase, an inverse modeling study estimated regional and sectoral emission changes for 2016-2022. Three inverse estimates based on different sets of atmospheric CH4 observations (surface observations only, surface and aircraft observations, and GOSAT observations) consistently suggest notable emission increases from 2016-2019 to 2020-2022 in the tropics (15° S-10° N) (10-18 Tg CH4 yr-1) and in northern low latitudes (10-35° N) (ca. 20 Tg CH4 yr-1), the latter of which likely contributed to the growth rate surge from 2020. The emission increase... (More)
Atmospheric methane (CH4) growth rates reached unprecedented values in the years 2020-2022. To identify the main drivers of this increase, an inverse modeling study estimated regional and sectoral emission changes for 2016-2022. Three inverse estimates based on different sets of atmospheric CH4 observations (surface observations only, surface and aircraft observations, and GOSAT observations) consistently suggest notable emission increases from 2016-2019 to 2020-2022 in the tropics (15° S-10° N) (10-18 Tg CH4 yr-1) and in northern low latitudes (10-35° N) (ca. 20 Tg CH4 yr-1), the latter of which likely contributed to the growth rate surge from 2020. The emission increase in the northern low latitudes is attributed to emissions in South Asia and northern Southeast Asia, which abruptly increased from 2019 to 2020, and elevated emissions continued until 2022. Meanwhile, the tropical emission increase is dominated by Tropical South America and Central Africa, but emissions were continuously increasing before 2019. Agreement was found in the sectoral estimates of the three inversions in the tropics and northern low latitudes, suggesting the largest contribution of biogenic emissions. Uncertainty reductions demonstrate that the flux estimates in Asia are well constrained by surface and aircraft observations. Furthermore, a sensitivity test with the probable reduction of OH radicals showed smaller emissions by up to 2-3 Tg CH4 yr-1 in each Asian region for 2020, still suggesting notable emission contributions. These results highlight the importance of biogenic emissions in Asian regions for the persistent high growth rate observed during 2020-2022.
(Less)
- author
- Niwa, Yosuke
; Tohjima, Yasunori
; Terao, Yukio
; Saeki, Tazu
; Ito, Akihiko
; Umezawa, Taku
; Yamada, Kyohei
; Sasakawa, Motoki
; Machida, Toshinobu
; Nakaoka, Shin Ichiro
; Nara, Hideki
; Tanimoto, Hiroshi
; Mukai, Hitoshi
; Yoshida, Yukio
; Morimoto, Shinji
; Takatsuji, Shinya
; Tsuboi, Kazuhiro
; Sawa, Yousuke
; Matsueda, Hidekazu
; Ishijima, Kentaro
; Fujita, Ryo
; Goto, Daisuke
; Lan, Xin
; Schuldt, Kenneth
; Heliasz, Michal
LU
; Biermann, Tobias
LU
; Chmura, Lukasz
; Necki, Jarsolaw
; Xueref-Remy, Irène
and Sferlazzo, Damiano
(Less) - organization
- publishing date
- 2025-07-07
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Atmospheric Chemistry and Physics
- volume
- 25
- issue
- 13
- pages
- 29 pages
- publisher
- Copernicus GmbH
- external identifiers
-
- scopus:105017325551
- ISSN
- 1680-7316
- DOI
- 10.5194/acp-25-6757-2025
- language
- English
- LU publication?
- yes
- additional info
- Publisher Copyright: © 2025 Yosuke Niwa et al.
- id
- b015dd12-e497-4a54-aa84-ccf7836b65e0
- date added to LUP
- 2025-10-13 16:39:41
- date last changed
- 2025-10-15 03:50:52
@article{b015dd12-e497-4a54-aa84-ccf7836b65e0,
abstract = {{<p>Atmospheric methane (CH<sub>4</sub>) growth rates reached unprecedented values in the years 2020-2022. To identify the main drivers of this increase, an inverse modeling study estimated regional and sectoral emission changes for 2016-2022. Three inverse estimates based on different sets of atmospheric CH<sub>4</sub> observations (surface observations only, surface and aircraft observations, and GOSAT observations) consistently suggest notable emission increases from 2016-2019 to 2020-2022 in the tropics (15° S-10° N) (10-18 Tg CH<sub>4</sub> yr<sup>-1</sup>) and in northern low latitudes (10-35° N) (ca. 20 Tg CH<sub>4</sub> yr<sup>-1</sup>), the latter of which likely contributed to the growth rate surge from 2020. The emission increase in the northern low latitudes is attributed to emissions in South Asia and northern Southeast Asia, which abruptly increased from 2019 to 2020, and elevated emissions continued until 2022. Meanwhile, the tropical emission increase is dominated by Tropical South America and Central Africa, but emissions were continuously increasing before 2019. Agreement was found in the sectoral estimates of the three inversions in the tropics and northern low latitudes, suggesting the largest contribution of biogenic emissions. Uncertainty reductions demonstrate that the flux estimates in Asia are well constrained by surface and aircraft observations. Furthermore, a sensitivity test with the probable reduction of OH radicals showed smaller emissions by up to 2-3 Tg CH<sub>4</sub> yr<sup>-1</sup> in each Asian region for 2020, still suggesting notable emission contributions. These results highlight the importance of biogenic emissions in Asian regions for the persistent high growth rate observed during 2020-2022.</p>}},
author = {{Niwa, Yosuke and Tohjima, Yasunori and Terao, Yukio and Saeki, Tazu and Ito, Akihiko and Umezawa, Taku and Yamada, Kyohei and Sasakawa, Motoki and Machida, Toshinobu and Nakaoka, Shin Ichiro and Nara, Hideki and Tanimoto, Hiroshi and Mukai, Hitoshi and Yoshida, Yukio and Morimoto, Shinji and Takatsuji, Shinya and Tsuboi, Kazuhiro and Sawa, Yousuke and Matsueda, Hidekazu and Ishijima, Kentaro and Fujita, Ryo and Goto, Daisuke and Lan, Xin and Schuldt, Kenneth and Heliasz, Michal and Biermann, Tobias and Chmura, Lukasz and Necki, Jarsolaw and Xueref-Remy, Irène and Sferlazzo, Damiano}},
issn = {{1680-7316}},
language = {{eng}},
month = {{07}},
number = {{13}},
pages = {{6757--6785}},
publisher = {{Copernicus GmbH}},
series = {{Atmospheric Chemistry and Physics}},
title = {{Multi-observational estimation of regional and sectoral emission contributions to the persistent high growth rate of atmospheric CH4 for 2020-2022}},
url = {{http://dx.doi.org/10.5194/acp-25-6757-2025}},
doi = {{10.5194/acp-25-6757-2025}},
volume = {{25}},
year = {{2025}},
}