Accounting for methane

Methane is a potent greenhouse gas emitted by both human activity and the natural environment. Due to its relatively short atmospheric lifetime, controlling methane emissions is increasingly recognised as a powerful climate mitigation strategy.

The drivers of trends in methane concentrations in the atmosphere over past decades are still poorly understood. Simulations from a chemistry transport model and box model show that human activity is the main driver of a complex system.

Atmospheric methane trends over recent decades are driven by anthropogenic emissions with modifying effects of hydroxyl radical through anthropogenic emissions of nitrogen oxides and carbon monoxide and variable wetland emissions, suggest simulations from a combined numerical modelling approach.

A comprehensive aircraft survey of onshore oil and gas infrastructure in British Columbia finds that methane emissions may be 1.7 times higher than the official inventory and introduces a framework for compiling measurement-led regional greenhouse gas emissions data.

A framework for incorporating aerial measurements into existing inventory methods is demonstrated, revealing oil and gas sector methane emissions in British Columbia, Canada, 1.7 times official estimates with markedly different source profiles.

Agricultural ponds in the USA and Australia emit nearly double the amount of methane reported in their national greenhouse gas inventories, according to estimates derived from a combination of flux measurements from the literature and observations.

Sector-based methane emissions can be backed out from observed methane fluxes, using a Bayesian optimal estimation method. This could help with monitoring gas leaks from industry.

Greenhouse-gas emissions from the sanitation-service chain in Kampala may represent more than half of the total city-level emissions according to a whole-system analysis.

Stormwater retention ponds emit the greenhouse gases carbon dioxide and methane but store increasingly large amounts of carbon in their sediments over time, according to an observational study of carbon dynamics in stormwater ponds in southwest Florida.

Episodic methane leakage events from the seafloor of the Arctic–Atlantic gateway region occurred before and during the mid-Pleistocene transition, suggesting foraminiferal stable carbon isotope and source-specific biomarker analyses of borehole samples.

Tropical seagrasses and adjacent unvegetated mudflats both emit the greenhouse gases carbon dioxide and methane, though seagrasses have lower global warming potential relative to mudflats, suggest a year of high temporal resolution measurements of air-sea gas fluxes in the Red Sea.

Agricultural ponds in the USA and Australia emit nearly double the amount of methane reported in their national greenhouse gas inventories, according to estimates derived from a combination of flux measurements from the literature and observations.

A process-based carbon isotope biogeochemistry model substantially reduces uncertainty in regional and global estimates of the stable carbon isotopic composition of methane emissions from wetlands and suggests rising atmospheric concentrations are due to increased microbial emissions.

Wetlands dominate methane emissions in Amazonia, with the largest emissions in the east but no discernible temporal trend, according to nine years of atmospheric methane observations across Amazonia.

Microbial reduction and dissolution of reactive iron (III) mobilizes mineral-bound organic carbon, which contributes to carbon dioxide production and promotes methanogenesis and methane emission before complete permafrost thaw, according to an observational study along collapsing palsa hillslopes in Sweden.

Microbial anaerobic oxidation of methane may not substantially mitigate projected warming-induced emissions of methane from marine hydrate-bearing sediments, according to a coupled hydraulic-thermodynamic-geomechanical hydrate model.

Phases of high bottom water temperature in the northwestern Barents Sea caused repeated destabilization of methane gas hydrates since the last glacial, according to a foraminifera Mg/Ca bottom water temperature record and hydrate stability modelling

Methane can increase groundwater arsenic contamination by triggering the dissolution of arsenic-bearing iron oxide minerals by methane-oxidizing microorganisms, according to microcosm experiments on arsenic-bearing sediments from the Red River Delta, Vietnam.