Impact of hydrogen on atmospheric composition and climate

Hydrogen(H2) is one of the most abundant greenhouse gases in the atmosphere that participates in stratospheric ozone depletion and influences air quality. Using hydrogen as an alternative energy source to meet net-zero carbon emissions by 2050 can increase the risk of Hydrogen Leakage. Excess H2 leaked from a hydrogen economy could travel from the Earth’s surface to the stratosphere, where its oxidation would increase water vapor (H2O) in the upper atmosphere. It also has the potential to modify stratospheric ozone destruction by altering catalytic reactions involving HOx (=OH+HO2) radicals as well as changing stratospheric temperatures. Additional H2 in the air would consume the hydroxyl radical (OH) and lengthen the atmospheric lifetime of methane (CH4), increasing its abundance, whilst the oxidation of both H2 and CH4 generates tropospheric O3. The changes in OH can cause a cascade of climate impacts that includes changes in aerosol clouds. Increases in H2 will increase the concentration of CH4, O3, and H20, resulting in increased radiative forcing. Here, we are using the UK Earth System Model (UKESM) chemistry-climate model to see the effect of indirect radiative forcing arising from increases in H2 in the atmosphere. We have conducted experiments at present and future H2 and CH4 concentrations and analyzed the feedback on O3, aerosol, and stratospheric H2O over the period of 40 years. The highlight of the study is to see the effects of radiative forcing on CH4, O3, and H2o separately . We have seen the effect on one component at a time by switching off the feedback of the other components and also see the effect of radiative forcing as a whole due to an increase in H2 concentration.