Indirect moistening of the upper atmosphere by black carbon from rocket exhaust

<jats:p>We present simulations from two Earth system models in which liquefied natural gas (LNG) rocket fuel burning injects gaseous and particulate material into the stratosphere during liftoff. We considered two heavy rocket launch scenarios representative for the year 2050, one with 1000 launches per year, a scenario equivalent with present-day emissions using kerosene propellant, and another with 10 times more. Injected species that include gaseous carbon monoxide, nitrogen oxides, and water vapor showed marginal or insignificant changes in atmospheric composition, while particulate black carbon was found to be the most influential of all injected material, via feedbacks that involve tropopause and stratospheric warming, followed by a moistening of the stratosphere via tropospheric water vapor intrusions. The fact that the LNG is still a concern via aerosol pollution in our simulations, despite burning more efficiently than conventional fuels, underscores the need to better understand the future climate impacts of space flight on atmospheric composition and climate.</jats:p>