Global methane emissions rebounded in 2024 despite a deceleration in atmospheric growth
摘要
Following record-breaking surges in 2020 and 2021 and highly elevated growth in 2022, atmospheric methane (CH4) growth decelerated in 2023 and 2024, returning to pre-2020 levels. Here, using the Global ObservatioN-based system for monitoring Greenhouse Gases (GONGGA) inversion that assimilates a blended and bias-corrected TROPOMI + GOSAT XCH4 dataset, we estimated global CH4 budgets for 2019–2024 and partitioned the drivers of the observed growth-rate anomalies. We find that reduced hydroxyl radical (OH) concentrations were a primary driver of the highly elevated growth during 2020–2022, reducing the atmospheric sink by an average of 14.3 Tg CH4 yr−1, while OH recovery and higher CH4 abundance subsequently strengthened the sink in 2023–2024 relative to 2019. Despite this strengthened sink, wetland emissions rebounded strongly in 2024 and offset elevated sink, producing an atmospheric growth rate near 2019 levels. Partial correlation analysis indicates precipitation anomalies as the dominant driver of wetland variability. However, process-based wetland models diverged from the inversions in key regions, underscoring the need to reconcile bottom-up and top-down estimates. Our findings indicate that combined variability of natural sources and sinks (12.6 Tg CH4 yr−1) is comparable to the pledged reductions, highlighting the importance of accounting for natural variability in methane monitoring.