A new paper just published in the Proceedings of the National Academy of Sciences points to a different culprit.
abstract
The abundance of methane in the atmosphere (CH4) reaches a record high of 15.4 ppb per year−1 Between 2020 and 2022, but the mechanism driving CH acceleration4 So far, growth is unclear. In this work we use the measurement 13C:12C ratio of CH4 (expressed as d13CMethane) from NOAA's Global Greenhouse Gas Reference Network and a box model to investigate potential drivers of rapid CH4 grow. These measurements indicate that the record CH4 Growth in 2020-2022 comes with sharp decline d13CMethaneshowing an increase in CH4 Abundance is primarily driven by increased emissions from microbial sources, e.g. Wetlands, waste and agriculture. We use a box model to reject increased fossil fuel emissions or reduced hydroxyl radical sinks as primary drivers of increasing global methane abundance.
https://www.pnas.org/doi/10.1073/pnas.2411212121
Methane (CH4) is the second most abundant anthropogenic greenhouse gas, with a 100-year global warming potential (GWP) of 28 (1); as a result, CH4 Have severe near-term radiation effects and are important targets for mitigation (2). After a brief pause in growth from 1999 to 2006, the abundance and growth rate of atmospheric methane has been increasing (3). During 2020-2022, the observed CH4 The growth rate is the highest since NOAA measurements began in 1983, averaging 15.4 ± 0.6 ppb per year−1 (4). Understanding the mechanisms driving this accelerated growth is critical to predicting its future climate impacts and providing scientific support for climate mitigation strategies (2).
Carbon isotope composition of atmospheric CH4 (d13CMethane) is a powerful tool for tracking atmospheric CH sources and sinks4. different channels4 The source is distinctive d13CMethane Value: Microbial CH4 Lower emissions (wetlands, livestock, landfills, etc.) d13CMethane Values (global average – 62‰) are higher than those of pyrolysis (biomass and biofuel combustion, global average – 24‰) and fossil fuel CH4 Emissions (global average is –45‰) (5). Various sinks of atmospheric CH4 Also has unique isotope effects. Therefore, comprehensive observations of atmospheric CH4 mole fraction sum d13CMethane Can provide unique constraints on changes in global CH4 Sources and sinks during rapid CH after 20064 grow.
The National Oceanic and Atmospheric Administration’s Global Monitoring Laboratory (NOAA/GML) has been carefully monitoring global CH4 For more than 40 years, we have been easing the burden through the Global Greenhouse Gas Reference Network (GGGRN). A collaboration between NOAA/GML and the Institute for Arctic and Alpine Research (INSTAAR) at the University of Colorado Boulder enables d13CMethane GGGRN has been conducting measurements since 1998 and currently conducts weekly or biweekly measurements from 22 background sites distributed around the world (6). This dataset has been widely used to study the evolution of global CH4 Source and sink (7-9). Here we report our latest observations of atmospheric CH4 mole fraction sum d13CMethane values to the end of 2022 and then use box modeling to examine and quantify the contribution of underlying drivers of record CH4 growth rate.
The rest of this article can be found here.
This is unlikely to appease climate fanatics, as agriculture is cited as one of the potential causes. There is an explosion of biological activity around the world due to CO2 fertilization, and I personally wonder to what extent this is increasing wetland productivity and thriving soil microorganisms.
H/T Steve Milloy.
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