The Post‐2020 Surge in Global Atmospheric Methane Observed in Ground‐Based Observations

Methane (CH$_4$) is a potent greenhouse gas with high radiative forcing and a relatively short atmospheric lifetime of around a decade. We used a decade‐long data set (2011–2022) from the Fourier transform spectrometer at the California Laboratory for Atmospheric Remote Sensing (CLARS‐FTS) to quantify a dramatic increase in methane observed in 2020. We report a significant acceleration of the short‐term growth rate of 1.37 ± 0.20 ppb/month starting in 2020 until the end of 2021, a substantial increase relative to the near‐zero and negative rates of the preceding 4 years (2016–2019). The observed increase in methane
concentrations in 2020 is of significant concern due to its potential contribution to global warming. The Total Carbon Column Observing Network (TCCON) is then used to examine the global geospatial variability of the increase in methane. The results suggest an approximately uniform rise in methane globally. Finally, results from a two‐box model used to simulate atmospheric chemical processes of methane production and loss indicate that changes in OH alone are insufficient to explain the rise in atmospheric methane. Recent data from 2022 suggest a deceleration in the methane growth rate, indicating a potential slowdown in the methane increase observed in 2020.