Antarctic Ozone Hole At Record Size

3:56pm UK, Friday August 22, 2003

The ozone hole over the Antarctic is growing at a rate that could be headed for a record size this year.

Australian scientists say the growth in the hole is due to colder temperatures in the stratosphere.

Stratospheric cloud from space
Picture: Nasa Visible Earth

Ozone is a protective layer in the atmosphere that shields the Earth from the sun's rays.

These include ultraviolet-B radiation that can cause skin cancer, cataracts and can harm marine life.

In 2000, NASA said the ozone hole expanded to a record 10.9 million sq miles.

This is three times the size of Australia or the United States, excluding Alaska.

Australian Antarctic Division scientist Andrew Klekociuk said: "The growth at the moment is similar to 2000 when the hole was a record size."

"This is in contrast to the situation in 2002 when unusually warm conditions produced the smallest ozone hole since 1988."

The ozone hole presently covers all of the Antarctic.

Mr Klekociuk said scientists at Australia's Davis Antarctic base saw the first signs of cooling of the lower stratosphere, nine to 15 miles up, about six weeks earlier than usual.

In a visual sign the ozone hole would grow rapidly this year, scientists at Australia's Mawson base reported the early appearance of stratospheric clouds.

Chemical reactions in the clouds convert normally inert man-made chlorofluorocarbons (CFCs) into ozone destroyers.

CFCs are commonly used as propellants in spray cans.

The full extent of the 2003 ozone hole will not be known until the end of September, as August and September are the coldest months for the South Pole.

Temperatures begin to warm by early October and the ozone layer will then start to recover.