Global Methane Budget 2000–2020
Earth System Science Data (Copernicus / Global Carbon Project)Marielle Saunois and more than 80 co-authors09 May 2025cc-byRead the original
Stated on the page: "© Author(s) 2025. This work is distributed under the Creative Commons Attribution 4.0 License." Confirmed, not assumed.
The third edition of the Global Carbon Project's living review of the methane budget covers 2000 to 2020, combining top-down atmospheric inversions using in situ and GOSAT satellite observations with bottom-up process models and inventories. For 2010 to 2019, inversions put global methane emissions at 575 teragrams per year, range 553 to 586, of which about 65 percent comes from direct human activity. The 2020 figure of 608 teragrams per year is the highest of the period and 12 percent above the 2000s average, with the trend since 2012 tracking scenarios that assume little or no climate mitigation. Bottom-up methods give 669 teragrams per year, 16 percent higher than top-down, though this gap has narrowed sharply from earlier editions and the uncertainty ranges now overlap. Wetlands and inland freshwaters, averaging 248 teragrams per year across a range of 159 to 369, remain the largest single source and the largest source of uncertainty. Agriculture and waste supply 211 to 228 teragrams and fossil fuels 115 to 120.
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"Understanding and quantifying the global methane (CH₄) budget is important for assessing realistic pathways to mitigate climate change. CH₄ is the second most important human-influenced greenhouse gas in terms of climate forcing after carbon dioxide (CO₂), and both emissions and atmospheric concentrations of CH₄ have continued to increase since 2007 after a temporary pause." "Two major challenges in quantifying the factors responsible for the observed atmospheric growth rate arise from diverse, geographically overlapping CH₄ sources and from the uncertain magnitude and temporal change in the destruction of CH₄ by short-lived and highly variable hydroxyl radicals (OH)." "global CH₄ emissions are estimated by atmospheric inversions (top-down) to be 575 Tg CH₄ yr⁻¹ (range 553–586)" "The 2020 emission rate is the highest of the period and reaches 608 Tg CH₄ yr⁻¹ (range 581–627), which is 12 % higher than the average emissions in the 2000s." "Bottom-up methods suggest 16 % (94 Tg CH₄ yr⁻¹) larger global emissions (669 Tg CH₄ yr⁻¹, range 512–849) than top-down inversion methods for the 2010–2019 period." "combined wetland and inland freshwater emissions average 248 [159–369] Tg CH₄ yr⁻¹"
Earth System Science Data (Copernicus / Global Carbon Project) · cc-by · Read the original
The MyGreenSuit briefing
Commentary by MyGreenSuit, not the words of Earth System Science Data (Copernicus / Global Carbon Project).
The number that should temper every methane story: the wetland and inland freshwater term is 248 teragrams a year, with a range of 159 to 369. That uncertainty band alone is wider than the entire fossil fuel source.
This is not an argument for doing less about oil and gas methane. Fossil methane is the fraction that is cheap to stop, precisely located and attributable to an owner — it is where effort pays. But it is an argument against confident claims about why atmospheric methane is rising, because the largest single source is also the least well constrained, and the natural-feedback question sits inside that range.
The other honest caveat is the 16 percent gap between bottom-up inventories and top-down atmospheric inversions. It has narrowed and the ranges now overlap, which is real progress, but it means numbers from the two approaches cannot be mixed in one sentence — a mistake that appears constantly in coverage.
A useful frame for the beat: agriculture and waste, at 211 to 228 teragrams, is nearly twice fossil fuels at 115 to 120. The attention allocation runs the other way.