Ozone layer hole over Arctic in sudden expansion
A huge hole that appeared in the Earth’s protective ozone layer above the Arctic in 2011 was the largest recorded in the northern hemisphere, though the sudden appearance of the hole was not due to man-made causes, scientists said in a report on Monday. The ozone layer high in the stratosphere acts like a giant shield against the sun’s ultraviolet (UV) radiation, which can cause skin cancer and cataracts. Since the 1980s, scientists have charted the size of the ozone hole every summer above the Antarctic. Some years, the holes have been so large that they covered the entire continent and stretched to parts of South America. During extreme events, up to 70% of the ozone layer can be destroyed, before it recovers months later. The hole above the Arctic was always much smaller – until March this year, when a combination of powerful wind patterns and intense cold temperatures high up in the atmosphere created the right conditions for already-present, ozone-eating chlorine chemicals to damage the layer. The findings, reported on Monday in the journal Nature, show that the hole had opened over northern Russia, parts of Greenland, and Norway, meaning people in these areas were likely to have been exposed to high levels of UV radiation.
