The impact of rocket-emitted chlorine on stratospheric ozone

Key findings from this study

• The study found that a 10-fold increase in rocket-emitted chlorine relative to 2019 causes global column ozone loss of less than 0.1 DU, while a 52-fold increase produces 0.6 DU depletion.
• The researchers demonstrate that ozone depletion scales linearly with chlorine enhancement throughout the stratosphere.
• The authors report that Antarctic and Arctic ozone impacts peak in October and April respectively, with Arctic depletion exceeding 8 DU during meteorologically cold years.

Overview

The study evaluates how chlorine emissions from an expanding space launch industry could influence stratospheric ozone recovery. Researchers model scenarios where rocket-emitted chlorine increases 10-fold and 52-fold relative to 2019 levels using the Whole Atmosphere Community Climate Model. The analysis assesses whether these emissions might partially offset ozone gains achieved through the Montreal Protocol.

Methods and approach

The researchers employed WACCM6 nudged to meteorological reanalyses to simulate realistic atmospheric variability. Two growth scenarios were modeled: a 10-fold and a 52-fold increase in rocket chlorine emissions relative to 2019 baseline. This approach enabled assessment of ozone column depletion and local stratospheric changes under different launch expansion pathways.

Results

A 10-fold increase in rocket chlorine emissions produces near-global column ozone loss of 0.04 percent (less than 0.1 DU), while a 52-fold increase results in 0.23 percent depletion (0.6 DU). Upper stratospheric ozone decreases reach 0.4 percent and 2 percent respectively for these scenarios. Ozone depletion scales linearly with chlorine enhancement across all stratospheric altitudes.

Polar regions show the largest column losses, with pronounced seasonality and meteorological variability. Antarctic ozone depletion peaks in October, reaching 0.5 DU and 3 DU for the 10-fold and 52-fold scenarios respectively. Arctic ozone impacts peak in April, typically reaching 2 DU under the 52-fold scenario but exceeding 8 DU during cold years with conditions similar to 2010/11.

Implications

Although projected ozone losses from expanded space launch activities remain modest under plausible growth scenarios, they represent a measurable offset to Montreal Protocol recovery gains. The linear relationship between chlorine enhancement and ozone depletion enables straightforward extrapolation for future launch rate projections. These findings indicate that regulatory frameworks for rocket propulsion systems warrant consideration in stratospheric ozone recovery assessments.

The high-latitude concentration of impacts and pronounced seasonal variability introduce complexity for polar ozone monitoring. Cold Arctic winter conditions can amplify ozone depletion effects substantially beyond typical scenarios. Continued tracking of space industry growth and emissions characterization will prove essential for accurate long-term ozone layer recovery projections.

Scope and limitations

This summary is based on the study abstract and available metadata. It does not include a full analysis of the complete paper, supplementary materials, or underlying datasets unless explicitly stated. Findings should be interpreted in the context of the original publication.