Speaker
Description
Rocket launches lofting payloads to orbit are unique anthropogenic injection points of emissions, emplacing gas and particulates while traveling up through the region of highest ozone concentration (15–35 km) at stratospheric altitudes. To understand if significant ozone losses could occur as the launch industry grows, we used a fully coupled aerosol-chemistry-climate model and examined two scenarios of industry aspirations, based on the linear extrapolation of well-documented year 2019 emissions. Our ‘ambitious’ scenario (2040 launches/year) yields a −0.29% depletion in annual-mean, near-global total column ozone in 2030. Antarctic springtime ozone decreases by 3.9%. Our ‘conservative’ scenario (884 launches/year) yields −0.17% annual, near-global depletion; current licensing rates suggest this scenario may be exceeded before 2030. Our analysis showed that ozone losses are mostly driven by the chlorine produced from solid rocket motor propellant, and black carbon which is emitted from most propellants. We additionally performed simulations of the potential geoengineering scenario through stratospheric injections of sulfur dioxide that elevates stratospheric sulfate aerosol levels. We found that this scenario can further amplify the negative effects of halogen-containing fuels through heterogeneous activation of reactive halogens on aerosol surfaces, which is mostly pronounced in the middle and high latitudes. The ozone layer is slowly healing from the effects of CFCs, yet global-mean ozone abundances are still 2% lower than measured prior to the onset of CFC-induced ozone depletion. Our results demonstrate that ongoing and frequent rocket launches could delay ozone recovery, which, however, depends on many factors including future climate scenarios, fuel types, launch locations, etc. Action is needed now to ensure that future growth of the launch industry and ozone protection are mutually sustainable.
