Global Methane Budget 2000–2020

• DOI: 10.5194/essd-2024-115
• Publication Date: 2024-06-06T07:08:48Z
• Authors: Marielle Saunois; Adrien Martinez; Benjamin Poulter; Zhen Zhang; Peter Raymond; Pierre Regnier; Joseph G. Canadell; Robert B. Jackson; Prabir K. Patra; Philippe Bousquet; Philippe Ciais; Edward J. Dlugoke...; Xin Lan; George H. Allen; David Bastviken; David J. Beerling; Dmitry A. Belikov; Donald R. Blake; Simona Castaldi; Monica Crippa; Bridget R. Deemer; Fraser Dennison; Giuseppe Etiope; Nicola Gedney; Lena Höglund-Isak...; Meredith A. Holge...; Peter O. Hopcroft; Gustaf Hugelius; Akihito Ito; Atul K. Jain; Rajesh Janardanan; Matthew S. Johnson; Thomas Kleinen; Paul Krummel; Ronny Lauerwald; Tingting Li; Xiangyu Liu; Kyle C. McDonald; Joe R. Melton; Jens Mühle; Jurek Müller; Fabiola Murguia-F...; Yosuke Niwa; Sergio Noce; Shufen Pan; Robert J. Parker; Changhui Peng; Michel Ramonet; William J. Riley; Gerard Rocher-Ros; Judith A. Rosentr...; Motoki Sasakawa; Arjo Segers; Steven J. Smith; Emily H. Stanley; Joel Thanwerdas; Hanquin Tian; Aki Tsuruta; Francesco N. Tubi...; Thomas S. Weber; Guido van der Werf; Doug E. Worthy; Yi Xi; Yukio Yoshida; Wenxin Zhang; Bo Zheng; Qing Zhu; Qiuan Zhu; Qianlai Zhuang

Abstract. Understanding and quantifying the global methane (CH4) budget is important for assessing realistic pathways to mitigate climate change. Emissions atmospheric concentrations of CH4 continue increase, maintaining as second most human-influenced greenhouse gas in terms forcing after carbon dioxide (CO2). The relative importance compared CO2 temperature change related its shorter lifetime, stronger radiative effect, acceleration growth rate over past decade, causes which are still debated. Two major challenges reducing uncertainties factors explaining well-observed arise from diverse, geographically overlapping sources uncertain magnitude temporal destruction by short-lived highly variable hydroxyl radicals (OH). To address these challenges, we have established a consortium multi-disciplinary scientists under umbrella Global Carbon Project improve, synthesise update regularly stimulate new research on cycle. Following Saunois et al. (2016, 2020), present here third version living review paper dedicated decadal budget, integrating results top-down emission estimates (based in-situ observing satellite (GOSAT) observations an ensemble inverse-model results) bottom-up process-based models estimating land-surface emissions chemistry, inventories anthropogenic emissions, data-driven extrapolations). We recent 2010–2019 calendar decade (the latest period full datasets available), previous 2000–2009 year 2020. revision this edition benefits progress inland freshwater with better accounting lakes ponds, reservoirs, streams rivers. This also reduces double across wetland and, first time, includes estimate potential that exists (average 23 Tg yr-1). Bottom-up approaches show combined average 248 [159–369] yr-1 decade. Natural fluxes perturbed human activities through climate, eutrophication, land use. In estimate, component contributing emissions. Newly available gridded products allowed us derive almost complete latitudinal regional based approaches. For estimated inversions (top-down) be 575 (range 553–586, corresponding minimum maximum model ensemble). Of amount, 369 or ~65 % attributed direct fossil, agriculture waste biomass burning 350–391 63–68 %). period, give slightly lower total than 2010–2019, 32 9–40). Since 2012, trends been tracking scenarios assume no minimal mitigation policies proposed Intergovernmental Panel Climate Change (shared socio-economic SSP5 SSP3). methods suggest 16 (94 yr-1) larger (669 yr-1, range 512–849) inversion period. discrepancy between budgets has greatly reduced differences (167 156 respectively), time uncertainty overlap. distribution inversion-based indicates predominance tropical southern hemisphere (~65 <30° N) mid (30° N–60° N, ~30 emissions) high-northern latitudes (60° N–90° ~4 emissions). similar though contributions latitudes, smaller tropics inversions. Although bottom-up, source attributable natural especially those wetlands freshwaters. identify five priorities improving budget: i) producing global, high-resolution map water-saturated soils inundated areas emitting robust classification different types ecosystems; ii) further development inland-water emissions; iii) intensification at local (e.g., FLUXNET-CH4 measurements, urban-scale monitoring, imagery pointing capabilities) scales (surface networks remote sensing measurements satellites) constrain both inversions; iv) improvements transport representation photochemical sinks inversions, v) integration 3D variational systems using isotopic and/or co-emitted species such ethane well information super-emitters detected (mainly oil sector but coal, landfills) improve partitioning. data presented can downloaded https://doi.org/10.18160/GKQ9-2RHT (Martinez al., 2024).