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Record Arctic Ozone Layer Hole April 8, 2011
Ozone layer graphic
Northwest Russia and parts of Scandinavia were under an ozone 'hole' on April 5, protected from harmful UV radiation by less than 200 Dobson Units of ozone.
The protective layer of stratospheric ozone over the Arctic reached a record low over the past winter due to abnormally cold weather in the upper atmosphere.

While surface weather around the North Pole continued to be unusually warm due to climate change, air nine to 10 miles aloft got very cold early and has continued to be that way into early April.

This, combined with man-made ozone-depleting chemicals lingering in the atmosphere, caused the destruction of 40 percent of stratospheric ozone by the end of March.

The previous record loss was 30 percent, which occurred several times over the past 15 years.

These ozone “holes” allow more harmful ultraviolet rays to reach the surface, increasing the chances of skin cancer, cataracts and damage to the immune system.

Ozone-depleting chemicals are being phased out due to the Montreal Protocol, which went into force in 1989.

But scientists say it takes several decades for compounds such as the chlorofluorocarbons formerly used as refrigerants to break down.

That means it could take until 2045-60 for the ozone holes over the Arctic and Antarctic to fully recover.

Image: NOAA Environmental Visualization Laboratory