The issues with Ozone

Ozone depletion, the process of O₃ being ‘destroyed’ follows the free radical substitution mechanism by which a radical (typically molecules containing halogens) initiate a reaction with Ozone which propagates. This propagation involves the destruction of Ozone and the conservation of the radical producing a chain reaction. A common misconception is that Sulphur Dioxide directly causes Ozone depletion. It doesn’t. The presence of Sulphur species in the Stratosphere act as a surface for these reactions to occur, hence they are named heterogeneous reactions.

Using the Whole-Atmosphere Community Climate Model, Rasch et al., produced the figure below to spatially represent the differing concentrations in ozone for a baseline and geo-engineering scenario in Antarctica; images a) and b), respectively. Image b) shows a greater region of ozone loss with the geoengineering simulation showing a reduction up to 60° away from the pole. Ozone concentrations are given in Dobson Units (DU), the geo-engineering results show an increased rate of ozone depletion with a difference of 25-35 DU compared to image a).

The authors realise, to better quantify the risk geo-engineering poses to ozone research must be conducted to better represent aerosol dynamics and chemistry in the computational fluid dynamics models utilised. Although a better quantification is needed, it is still clear the risk geo-engineering poses to the climate system. Much of the concern, regarding a reduction in Ozone, are the health hazards associated with increased exposure at the surface to UV-B and UV-C. Again, it is here where perspective must be taken on the advantages and disadvantages of Stratospheric Sulphate Injection as a method of Geo-engineering. Polar regions are one of the greater beneficiaries for geo-engineering with respect to temperature, with respect to feedback systems and the sensitive eco-systems. Dr. Friederike Otto of the EnvironmentalChange Institute at Oxford University has recently reported arctic temperatures to be almost 20°c warmer than average, an event with a return period of 1/1000 years, and it was only in December 2015 the temperatures were very similar.