The Post-2020 Surge in Global Atmospheric Methane Observed in
Ground-based Observations
Abstract
Methane (CH4) is a potent greenhouse gas with high radiative forcing and
a relatively short atmospheric lifetime of around a decade. We used a
decade-long dataset (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
an increase of 1.13 ppb/month starting in 2020 until the end of 2021,
compared to a growth rate of 0.345 ppb/month from 2016 to 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.
Encouragingly, recent data from 2022 suggest a deceleration in the
methane growth rate, indicating a potential slowdown in the methane
increase observed in 2020.