Today marks the 25th UN International Day for the Preservation of the Ozone Layer, commemorating the date of the signing of the Montreal Protocol which brought about a global initiative to ban Ozone Depleting Substances. Two Irish scientific atmospheric monitoring stations have played a significant role assessing the planet’s success in saving the ozone layer.

Over the last 25 years, atmospheric observations from NUI Galway’s Mace Head Station in Connemara and Met Éireann’s Valentia Observatory in Co. Kerry, have charted the success of international actions relating to man-made Ozone Depleting Substances (ODS).

The world was shocked 30 years ago to hear of the major threat posed by the hole in ozone layer. World governments responded by developing and eventually agreeing in 1987 the Montreal Protocol .The protocol phased out the use of man-made ODS, of which, the primary culprits where CFCs or chlorofluorocarbons used as refrigerants. CFCs provided a source of reactive chlorine in the upper atmosphere which destroyed ozone.

Combined observations from Mace Head and Valentia, supported by satellite data, illustrate that it took 15 years for the destructive chlorine trend to peak-out and turn into decline. As the destructive chlorine declined, stratospheric ozone concentrations slowly started to recover. The data are unique in Europe as they represent observations in Europe’s cleanest air and they demonstrate a gradually recovering ozone layer over the last 10 years.

Globally, the impact of CFCs is still evident. According to the IPCC AR5 Report, Climate Change 2013: The Physical Science Basis, it is certain that global stratospheric ozone has declined from pre-1980 values. Most of the decline occurred prior to the mid-1990s. Since then ozone has remained nearly constant at about 3.5% below the 1964–1980 level.

Ireland is strategically located to monitor the change in ODS and stratospheric ozone in the cleanest northern hemispheric air and at mid-latitudes which are heavily populated and susceptible to most impacts from the ozone hole.

Professor Colin O’Dowd, Director of NUI Galway’s Centre for Climate and Air Pollution Research, which operates Mace Head highlighted the importance of such observing and research infrastructures stating that: “Without these key long-term observations in strategic locations emerging environmental dangers, solutions, and response to interventions would be very difficult to identify, enable and quantify. It is essential that stakeholder support of such research and observation infrastructures is sustained and even expanded on into the future in order to improve environmental security and better inform response-policy development.”  

Eoin Moran, Assistant Director of Met Éireann, added: “The location of Valentia Observatory and Mace Head, are strategically important, nationally and internationally, providing important climate and environmental data at the interface between Europe and the Northeast Atlantic. The measurements at both stations are complimentary forming a very important component of the Global Atmosphere Watch programme – this work represents an excellent example of Ireland’s contribution to international scientific research – brought about through successful and sustained collaboration between world class research and operational scientists.”

Monitoring Ozone Recovery
The accumulation of CFCs in the atmosphere has been monitored at NUI Galway’s Mace Head Atmospheric Research Station since the early 1980’s. This globally important record was one of the first to demonstrate the reduction in CFCs a few years after the protocol for the most reactive CFCs. Mace Head operates with a World Meteorological Organisation ‘Global Atmosphere Watch’ (GAW) status in tandem with Met Éireann’s GAW station at Valentia Observatory where complementary stratospheric Ozone measurements are conducted.

The ozone measurements at Valentia contributed to the identification of the extent of ozone loss and eventually the initial beginnings of the expected recovery using special balloon-borne ozone detecting instruments (called ozonesondes) and a sophisticated ground based ozone sensor (called a Brewer Spectrophotometer).

The research by NUI Galway is conducted in cooperation with the Advanced Global Atmospheric Gas Experiment (AGAGE). More information on the observatories can be found on www.macehead.org and www.met.ie.

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