What is it? What is happening to it?
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In September 1982, Dr Joe Farman, a British scientist working in the Antarctic, found that a
dramatic change had taken place in the atmosphere above his research station on the ice continent.
His instruments, set up to measure the amounts of a chemical called ozone in the atmosphere,
seemed to go wild. Over just a few days they recorded that half the ozone had disappeared.
He couldn’t believe his eyes, so he came back to Britain to get a new instrument to check his findings. But when he returned the following year at the same time, the same thing happened. He had discovered a hole in the ozone layer – an invisible shield in the upper atmosphere – that turned out to extend over an area of the sky as wide as the United States and as deep as Mount Everest is high. When he published his findings in scientific journals, they caused a sensation. Scientists blamed pollution for causing the ozone hole.
The ozone layer is between 15 and 40 kilometers up in the atmosphere, higher than most aero-planes fly. This region contains most of the atmosphere’s ozone, which is a special form of the gas oxygen. Ozone has the unique ability to stop certain dangerous invisible rays from the sun from reaching the Earth’s surface – rather like a pair of sunglasses filters out bright sunlight. These rays are known as ultra-violet radiation. This damages living cells, causing sunburn and more serious diseases. The ozone layer is vital to life on the surface of the Earth.
Until the ozone layer formed, about two thousand million years ago, it was impossible for any living things to survive on the surface of the planet. All life was deep in the ocean. But once oxygen was formed in the air, and some of that oxygen turned to ozone , plants and animals could begin to move on to land.
But now humans are damaging the ozone layer for the first time. In the past ten years, scientists have discovered that some man-made gases, used in everything from refrigerators and aerosols to fire extinguishers, are floating up into the ozone layer and destroying the ozone. The most common of these gases are called chlorofluorocarbons (CFCs).
The damage is worst over Antarctica, and near the North Pole, where scientists have seen small holes appear far a short time each spring since 1989. So far, these holes healed up again within a few weeks by natural processes in the atmosphere that crate more ozone. But each year, seemed to take longer for the healing to be completed. Also, all round the planet, there now seems to be less ozone in the ozone layer than a few years ago.
The first new international law to stop people making or using CFCs was the Montreal Protocol, agreed by most of the world’s governments in 1987. Since then, there have been new controls on other chemicals that destroy ozone. The problem is that it takes roughly eight years for CFCs, which are released when an old fridge is broken up, to reach the ozone layer. That is why, despite all the cuts, ozone holes were deeper than ever around both the North and South Poles in 1993. Amounts of CFCs in the atmosphere will continue to rise for another five years, say scientists.
Every year, the atmosphere will attempt to repair damage to the ozone layer caused by our pollution. But we are stretching its capacity to recover to the limit. If we stop using all ozone-destroying chemicals within the next five years, it is likely to be at least the middle of the 21st century before the ozone hole stops forming over Antarctica each year. And, if we are to survive, we all have to face the problem now.