Major ozone loss over the Arctic now seems likely this winter given current weather conditions, according to the European Commission, which has started a new study to measure losses.
Huge chemical ozone depletion of up to 50 per cent at altitudes of between 15 and 20 km has occurred during each of the last three winters, the Commission said yesterday.
There has been a resultant 10 per cent decline in total ozone over northern Europe, including Ireland, during winter and spring, compared to levels measured in the late 1970s.
Early winter measurements in the Arctic stratosphere suggest that major loss could also occur during the next month or two, the Commission has warned. Ozone loss is greatest when a circular air movement called the polar vortex forms, when temperatures are very low and when cloud ice crystals are present. All these conditions now exist, and a large decline during later winter is likely.
The Commission yesterday opened its THESEO campaign, involving 400 scientists in 19 countries including Ireland. It carries forward earlier programmes during which helium balloons known as ozone sondes are sent aloft carrying sensitive measuring equipment. During their one-hour flights the sondes measure ozone levels at all altitudes up to 30 km.
Met Eireann and its Valentia, Co Kerry, weather station will participate in THESEO on Ireland's behalf, according to the chief scientist at Valentia, Mr Gerry Murphy. The sondes will be controlled by Met Eireann's specialists. "Because of our strategic location we will receive funding from the overall EU programme," he said yesterday. The Department of the Environment has also contributed £20,000.
The various European meteorological organisations track weather conditions and then launch sondes into the edge of the vortex or into polar air masses which break away from it. These masses, which pass high above Ireland and the rest of northern Europe during March, will have depleted ozone levels if chlorine and bromine compounds, which cause the ozone destruction, were present in the vortex.
Ozone shields life on Earth from excessive levels of ultraviolet (UV) radiation from the sun. Overexposure to UV causes sunburn, which can lead to skin cancers, and can also cause cataracts and loss of vision. The THESEO campaign will also look at ozone loss at lower latitudes. The total budget for this work is almost £10 million.
