Rapid shift in methane carbon isotopes suggests microbial emissions drove record high atmospheric methane growth in 2020-2022.

The growth rate of the atmospheric abundance of methane (CH) reached a record high of 15.4 ppb yr between 2020 and 2022, but the mechanisms driving the accelerated CH growth have so far been unclear. In this work, we use measurements of the C:C ratio of CH (expressed as C) from NOAA's Global Greenhouse Gas Reference Network and a box model to investigate potential drivers for the rapid CH growth.

Identifying emission sources of CH in East Asia based on in-situ observations of atmospheric δC-CH and CH.

Methane (CH) is the second most important greenhouse gas influenced by human activity. The increase in atmospheric CH concentrations contributed ~23 % to the anthropogenic radiative forcing (Saunois et al., 2020).

Upward revision of global fossil fuel methane emissions based on isotope database.

Methane has the second-largest global radiative forcing impact of anthropogenic greenhouse gases after carbon dioxide, but our understanding of the global atmospheric methane budget is incomplete. The global fossil fuel industry (production and usage of natural gas, oil and coal) is thought to contribute 15 to 22 per cent of methane emissions to the total atmospheric methane budget. However, questions remain regarding methane emission trends as a result of fossil fuel industrial activity and the contribution to total methane emissions of sources from the fossil fuel industry and from natural geological seepage, which are often co-located.