Recent acceleration of methane growth rate: leading contributions from tropical wetlands and China

Methane (CH₄) accounts for about a quarter of the warming induced by anthropogenic greenhouse gases since the preindustrial age. After stagnating in the early 2000s, its atmospheric growth rate has been positive since 2007 with a significant acceleration starting in 2014. While causes for previous growth rate variations are still not well determined, this recent increase can be studied with dense surface and satellite observations. Using an ensemble of multi-tracer atmospheric inversions, we show that the recent surge of the atmospheric growth rate between 2010-2013 and 2014-2017 is most likely explained by an increase of global CH₄ emissions by 17.5±1.5 Tg CH₄ yr^-1, while variations in CH₄ sinks remained small. The inferred emission increase is consistently supported by both surface and satellite observations, with leading contributions from tropical wetlands (~30%) and anthropogenic emissions in China (~22%). Such a high consecutive atmospheric growth rate has not been observed since the 1980s and corresponds to unprecedented global total CH₄ emissions, which may point to a risk of positive feedbacks between wetland emissions and climate warming.