Methane emissions decreased in fossil fuel exploitation and sustainably increased in microbial source sectors during 1990–2020

Methane (CH₄) emission reduction to limit warming to 1.5 °C can be tracked by analyzing CH₄ concentration and its isotopic composition (δ¹³C, δD) simultaneously. Based on reconstructions of the temporal trends, latitudinal, and vertical gradient of CH₄ and δ¹³C from 1985 to 2020 using an atmospheric chemistry transport model, we show (1) emission reductions from oil and gas exploitation (ONG) since the 1990s stabilized the atmospheric CH₄ growth rate in the late 1990s and early 2000s, and (2) emissions from farmed animals, waste management, and coal mining contributed to the increase in CH₄ since 2006. Our findings support neither the increasing ONG emissions reported by the EDGARv6 inventory during 1990–2020 nor the large unconventional emissions increase reported by the GAINSv4 inventory since 2006. Total fossil fuel emissions remained stable from 2000 to 2020, most likely because the decrease in ONG emissions in some regions offset the increase in coal mining emissions in China.

Naveen Chandra, Prabir K. Patra, Ryo Fujita, Lena Höglund-Isaksson, Taku Umezawa, Daisuke Goto, Shinji Morimoto, Bruce H. Vaughn, Thomas Röckmann