Sensitivity of methane to atmospheric and emission perturbations after the Pinatubo eruption

The growth rate of methane (CH4) showed fluctuations in the 1990s, with particularly large anomalies after the eruption of Mount Pinatubo in June 1991. The eruption injected about 18.5 Mt of sulphur dioxide (SO2) in the stratosphere, and triggered different photochemical effects, including feedbacks between climate and atmospheric photochemistry. These processes had both positive and negative impacts on the methane growth rate, affecting methane emissions and methane lifetime. We assess their magnitude using a steady state column model. We calculate the change in the chemical equilibrium state of our column atmosphere depending on emissions and atmospheric perturbations, as constrained by observations.