Abstract
Atmospheric methane's rapid growth from late 2006 is unprecedented in the observational record. Assessment of atmospheric methane data attributes a large fraction of this atmospheric growth to increased natural emissions over the tropics, which appear to be responding to changes in anthropogenic climate forcing. Isotopically lighter measurements of (Figure presented.) are consistent with the recent atmospheric methane growth being mainly driven by an increase in emissions from microbial sources, particularly wetlands. The global methane budget is currently in disequilibrium and new inputs are as yet poorly quantified. Although microbial emissions from agriculture and waste sources have increased between 2006 and 2022 by perhaps 35 Tg/yr, with wide uncertainty, approximately another 35–45 Tg/yr of the recent net growth in methane emissions may have been driven by natural biogenic processes, especially wetland feedbacks to climate change. A model comparison shows that recent changes may be comparable or greater in scale and speed than methane's growth and isotopic shift during past glacial/interglacial termination events. It remains possible that methane's current growth is within the range of Holocene variability, but it is also possible that methane's recent growth and isotopic shift may indicate a large-scale reorganization of the natural climate and biosphere is under way.
| Original language | English |
|---|---|
| Article number | e2023GB007875 |
| Pages (from-to) | 1-33 |
| Number of pages | 33 |
| Journal | Global Biogeochemical Cycles |
| Volume | 37 |
| Issue number | 8 |
| DOIs | |
| Publication status | Published - Aug 2023 |
Bibliographical note
Publisher Copyright:© 2023. The Authors.
Funding
EGN, DL, REF, JLF, and the Royal Holloway laboratory thank the UK Met Office for three decades of support on Ascension Island. We thank NILU-Norway, IUP Heidelberg, and Environment Canada for sampling at Zeppelin, Svalbard and Alert, Canada, the South African Weather Service for sampling at Cape Point, and the British Antarctic Survey. D.Lowe and K.Lassey of NIWA New Zealand and I.Levin of IUP Heidelberg helped generously in our early start-up, as did P.Crutzen, R. Cicerone and A. Roddy. EGN thanks the UK Natural Environment Research Council for grants NE/S00159X/1 ZWAMPS Quantifying Methane Emissions in remote tropical settings: a new 3D approach and NE/N016238/1 MOYA: The Global Methane Budget, and colleagues involved with the UNEP International Methane Emissions Observatory for discussions and insight. XL thanks NOAA Cooperative agreement NA22OAR4320151. REF thanks NERC for Grant NE/V000780/1 Methane D/H Discovering reasons for global atmospheric methane growth using deuterium isotopes. PIP acknowledges support from the UK National Centre for Earth Observation funded by the Natural Environment Research Council (NE/R016518/1). TR's laboratory was supported in part by the European Union's Marie Curie project MEMO2 (Methane goes Mobile—Measurements and Modeling) and ATMO ACCESS. EGN, DL, REF, JLF, and the Royal Holloway laboratory thank the UK Met Office for three decades of support on Ascension Island. We thank NILU‐Norway, IUP Heidelberg, and Environment Canada for sampling at Zeppelin, Svalbard and Alert, Canada, the South African Weather Service for sampling at Cape Point, and the British Antarctic Survey . D.Lowe and K.Lassey of NIWA New Zealand and I.Levin of IUP Heidelberg helped generously in our early start‐up, as did P.Crutzen, R. Cicerone and A. Roddy. EGN thanks the UK Natural Environment Research Council for grants NE/S00159X/1 ZWAMPS Quantifying Methane Emissions in remote tropical settings: a new 3D approach and NE/N016238/1 MOYA: The Global Methane Budget, and colleagues involved with the UNEP International Methane Emissions Observatory for discussions and insight. XL thanks NOAA Cooperative agreement NA22OAR4320151. REF thanks NERC for Grant NE/V000780/1 Methane D/H Discovering reasons for global atmospheric methane growth using deuterium isotopes. PIP acknowledges support from the UK National Centre for Earth Observation funded by the Natural Environment Research Council (NE/R016518/1). TR's laboratory was supported in part by the European Union's Marie Curie project MEMO (Methane goes Mobile—Measurements and Modeling) and ATMO ACCESS. 2
| Funders | Funder number |
|---|---|
| European Union's Marie Curie | |
| IUP Heidelberg | |
| NILU-Norway | |
| NOAA Cooperative | NA22OAR4320151 |
| Environment and Climate Change Canada | |
| UK Natural Environment Research Council | NE/R016518/1 |
| European Commission | |
| Met Office | |
| British Antarctic Survey |
Keywords
- atmospheric methane growth driven by biogenic sources
- glacial/interglacial comparison
- sudden global climate change
