Multi-observational estimation of regional and sectoral emission contributions to the persistent high growth rate of atmospheric CH<sub>4</sub> for 2020–2022
<p>Atmospheric methane (CH<span class="inline-formula"><sub>4</sub></span>) 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 chan...
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| Main Authors: | , , , , , , , , , , , , , , , , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2025-07-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/25/6757/2025/acp-25-6757-2025.pdf |
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| Summary: | <p>Atmospheric methane (CH<span class="inline-formula"><sub>4</sub></span>) 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<span class="inline-formula"><sub>4</sub></span> 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<span class="inline-formula"><sub>4</sub></span> yr<span class="inline-formula"><sup>−1</sup></span>) and in northern low latitudes (10–35° N) (ca. 20 Tg CH<span class="inline-formula"><sub>4</sub></span> yr<span class="inline-formula"><sup>−1</sup></span>), 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<span id="page6758"/> 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<span class="inline-formula"><sub>4</sub></span> yr<span class="inline-formula"><sup>−1</sup></span> 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> |
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| ISSN: | 1680-7316 1680-7324 |