Methane (CH4) is a potent greenhouse gas (GHG) with 25 times the global warming potential of carbon dioxide (CO2) and is the second-most abundant GHG after CO2.
After almost a decade of stagnation, atmospheric methane has been rising steadily since 2007 but the causes for this renewed increase are still largely unknown. The increase in global concentrations has been accompanied by a shift in isotopic signatures, which suggests that biogenic sources (rather than anthropogenic ones) are driving the rise in atmospheric methane.
Emissions from tropical wetlands and agriculture are believed to be the major drivers behind the renewed increase in atmospheric methane but there are currently insufficient measurements in the tropics to assess the magnitude of these emissions and to understand how these might respond to changes in environmental and meteorological conditions.
There is hence a timely need to identify the biogenic sources of methane and their controls, study the processes underpinning them and quantify their emissions in order to better predict their future impact on climate and identify possible mitigation options.