The atmospheric formaldehyde budget and its modulation by methane and hydrogen

Atmospheric formaldehyde is an air pollutant and a crucial component of the methane and hydrogen chemical budgets. Using simulations representative of the atmosphere between 2010 and 2019, we have analysed the global budget for formaldehyde and investigated the cause of changes during this period. Methane and hydrogen are both intricately coupled to the future energy pathway the global community takes. Currently, the anthropogenic emissions of methane and the emissions of hydrogen from production are rising, although efforts such as the Global Methane Pledge aim to counteract this. The complex balance of how these species evolve over the coming decades will influence formaldehyde. Sensitivity simulations using perturbations of methane and hydrogen have allowed the influence of these species on the budget of formaldehyde to be assessed. These simulations aim to elucidate these relationships, by unpicking how the fluxes of the reactions which control formaldehyde are changed when methane or hydrogen are perturbed. This will allow better prediction of the future evolution of formaldehyde. These simulations have been run using the atmosphere-only version of UKESM1.0, a global Earth System Model with the StratTrop chemical mechanism. This research contributes to both the “HYway: Climate Impacts of a Hydrogen Economy” project, and “VOCMIP: Volatile Organic Compound Model Intercomparison Project”.