Modeling the photochemical origins of the extreme deuterium enrichment in stratospheric H2
Hydrogen fuel cells produce energy from the controlled oxidation of molecular hydrogen (H2) and have been proposed as an alternative to direct fossil fuel combustion. However, a shift to hydrogen fuel cell technologies would likely increase anthropogenic H2 emissions due to leakage from the requisite infrastructure. If such emissions result in significant increases in atmospheric H2, changes in regional air quality and reduction of stratospheric ozone have been predicted. Uncertainties in the magnitudes of the current sources and sinks of H2 (known collectively as the H2 budget), however, preclude a reliable evaluation of these potential effects. Because many of the sources and sinks of H2 have distinct isotopic signatures, the deuterium content of atmospheric H2 can serve as a constraint on budget estimates. Our study focuses on quantifying uncertainties in the isotopic composition of H2 produced photochemically from methane oxidation and prioritizing the measurements necessary to reduce these uncertainties.
