Losing the ozone layer
Fortunately, almost all of the harmful UV radiation is absorbed by a layer of ozone gas 20 – 50 km above the Earth. However, ozone is a form of oxygen that can be destroyed easily by certain man-made chemicals.
In 1987, the leading industrial countries agreed to phase out these chemicals. Even so, satellites have shown that thinning of the ozone layer has continued over Antarctica. The ozone hole reached a record size in 2000, when it covered nearly 30 million sq. km, roughly the size of the North American continent. In 2006, an even greater amount of ozone was lost from the atmosphere, even though the hole was slightly smaller.
Smaller ozone holes have also appeared over the Arctic. These holes allow more UV light to reach densely populated areas of Europe.
Europe’s first polar orbiting weather satellite, MetOp-A, carries an advanced ozone-monitoring instrument. Envisat carries three instruments that can study ozone and the pollutants that attack it in the upper atmosphere.
Last update: 15 November 2010