3rd Prize of the Year 2023
Dr. Sabine Robrecht
Potential depletion of ozone in the mid-latitude lowermost stratosphere in summer under geoengineering condition
IEK-7: Stratosphere, Research Center Jülich
The research work of Dr. Sabine Robrecht deals with the assessment of the risk of ozone depletion when applying sulphate geoengineering (SGE), a much discussed approach to combat climate change.
It has been looking at whether the introduction of sulphate aerosols into the stratosphere to block sunlight and cool the Earth's surface leads to chemical ozone depletion cycles in the mid-latitudes. This could reduce the ozone layer and thus increase UV exposure in these regions, such as over North America.
The research work is based on detailed analyses of the ozone depletion mechanism and its sensitivity to different conditions. For this purpose, box model simulations were carried out using the "Chemical Lagrangian Model of the Stratosphere" (CLaMS). Through these simulations, it was possible to identify a threshold value in the water vapour mixing ratio that must be exceeded for ozone depletion to occur. This threshold is mainly influenced by the temperature and the sulphate content in the stratosphere.
Based on these findings, the probability of occurrence of this ozone depletion mechanism was determined under present and future conditions. Both a climate change scenario and the additional application of SBU were considered. By comparing atmospheric conditions leading to ozone depletion with the results of global climate simulations in the lower stratosphere, it was shown that under SGE conditions the probability of occurrence of this mechanism is 2-3 times higher than under present conditions.
Nevertheless, the probability of ozone depletion, even under SBU conditions, remains at a maximum of about 3.3%. This corresponds to a negligible fraction of less than 0.1% of the ozone column that would be destroyed. These results contribute to a comprehensive assessment of the potential risks that may be associated with the use of SGE.
Dr Sabine Robrecht's award underlines the importance of her research for the scientific community and the debate on geoengineering as a possible solution to climate change. Her findings are an important contribution to this.
