Contributed by Marilyn Raphael, UCLA
A WCRP Special Workshop on the ‘Climatic Effects of Ozone Depletion in the Southern Hemisphere: Assessing the evidence and identifying gaps in the current knowledge’, was convened at the Pontificia Universidad Católica Argentina, Buenos Aires, Argentina, from 25 February to 1 March, 2013.
The WCRP Special Workshop was held to examine our understanding of the links between stratospheric ozone depletion and recovery and the climate of the Southern Hemisphere including the Southern Ocean. Our understanding of the influence of increasing greenhouse gas concentration was also examined. Of immediate relevance to the CliC community is the discussion of the links between observed changes in the atmospheric circulation due to stratospheric ozone depletion and contemporary Antarctic surface temperature and sea ice trends. While the links to surface temperature changes in regions such as the Peninsula are clear, those to sea ice changes are not. The discrepancy between the modeled and observed sea ice trends was highlighted as an area for future research with specific reference to the need for a better understanding of sea ice formation processes and the interaction with the ocean and atmosphere. Download the report
The workshop aims were to discuss our current understanding of Southern Hemisphere ozone depletion, in particular high latitude ozone depletion, its impacts on hemispheric climate and relative role with respect to greenhouse gas (GHG) induced climate changes. Discussions were initiated from results published in the last 2010 UNEP/WMO Scientific Assessment of Ozone Depletion and research published since. The workshop was supported by WCRP, the Agencia Nacional de Promoción Científica y Técnica (Argentina), the National Science Foundation (USA), NASA (USA) and the Pontificia Universidad Católica Argentina.
The main conclusions from the last Ozone Assessment, relevant to the workshop topics, can be summarized as follows:
1. There is new and stronger evidence for radiative and dynamical links between stratospheric change and specific surface climate changes.
2. Changes in stratospheric ozone, water vapour and aerosols all radiatively affect surface temperature.
3. Observations and model simulations show that the Antarctic ozone hole caused much of the observed southward shift of the Southern Hemisphere mid-latitude tropospheric jet during summer since 1980.
4. This southward shift has been linked to a range of observed climate trends in the Southern Hemisphere mid- and high latitudes during summer.
5. The influence of stratospheric changes on climate will continue even after ozone is no longer affected by emissions of ozone depleting substances.
6. Future recovery of the Antarctic ozone hole and increases in GHGs are expected to have opposing effects on the Southern Hemisphere mid-latitude jet.