Press release archive: 2011

Nature: Unprecedented ozone hole over the Arctic in spring

4.10.2011 11:07

The scientific journal Nature has published an article on an ozone hole detected over the Arctic polar region last spring. According to the article, for the first time in the observational record, the ozone hole was comparable to that over the Antarctic.



The article points out that the ozone hole formed over the northern hemisphere in March reached record-breaking dimensions owing to the combined effect of exceptionally cold conditions in the lower stratosphere and high concentrations of ozone-destroying forms of chlorine. Because the cold period lasted until early April, the ozone-destroying chlorine compounds remained active unusually long in spring. In consequence, 80 per cent of the central ozone layer at an altitude of 18–20 kilometres was destroyed. Researchers from the Finnish Meteorological Institute participated in the study, which utilised ozone observations made by the Institute.

Ozone depletion occurs in both polar regions every spring, but it is unprecedented that the phenomenon was so strong in the Arctic polar region. In the considerably colder ozone layer over the Antarctic, a vast ozone hole has formed every year during the local spring since the late 1980s.

The extensive scientific project led by NASA had participants from 19 research institutes in nine countries. The Finnish scientists involved in the project came from the Arctic Research Centre of the Finnish Meteorological Institute.

Additional information:

Research Professor Esko Kyrö, tel. 040 552 7438,
Research Scientist Rigel Kivi, tel. (016) 619 624,

Nature’s abstract on the subject: