Published on Wednesday, April 5, 2000 in the Manchester (UK) Guardian
New Study: Ozone Layer Over Europe Thinner By Two-Thirds
by Tim Radford

Scientists measuring the ozone layer - the planet's sunscreen - over northern Europe have found that almost two-thirds has been lost in one of the coldest stratospheric winters on record.

The losses above the Arctic mean that ozone levels over Europe will be thinner in the next few weeks. Ozone, an unusual form of oxygen, is a pollutant at ground level but blocks ultraviolet radiation in the upper atmosphere. Less ozone protection means a greater risk of skin cancers and cataracts.

The message is that, even though developed nations have stopped using the chemicals that endanger the ozone layer, the damage goes on.

The most dramatic ozone depletion occurs over the Antarctic: in 1985 British scientists identified a hole the size of the US and as deep as Everest. There were swift international steps to ban releases of the ozone-destroying chemicals chlorofluorocarbons which, in a complicated reaction with intense cold and the first sunshine of the polar spring, caused huge ozone destruction each September. Since then there has been concern about similar processes over Europe each spring.

Scientists from Europe, the US, Canada, Russia and Japan have been cooperating on detailed measurement of the chemistry of the atmosphere at high altitudes. Between January and March, they said in a report out today, there were cumulative losses of 60% at altitudes of around 18km.

The witches' brew needed to destroy the planet's sunscreen involves chlorine from CFCs, very low temperatures and clouds in the stratosphere. When conditions are right, one molecule of chlorine can destroy thousands of molecules of ozone.

In the Antarctic it happens every year. In the Arctic the conditions are less stable, and European scientists try not to talk of "holes" in the ozone layer. But there has been a pattern of continuous destruction none the less. On January 28 the area covered by temperatures low enough for clouds to form was 14.8m square kilometres. Europe covers only 10m sq km.

Georgios Amanatidis, one of the scientists in the group, said even though chlorine levels were falling the problem would continue. Global warming in the lower atmosphere, leading to a thinning and shrinking of Arctic ice, had led to greater cold in the upper atmosphere, creating more destructive conditions. The threat to public health from any episode of ozone loss was not great, he said. But the risks of exposure to ultraviolet were cumulative.

Guardian Newspapers Limited 2000