Ozone hole to start shrinking and will close in 50 years, say scientists (2002)

The hole in the ozone layer over Antarctica is about to start shrinking and will close by 2050, Australian researchers say.

Government scientists in Tasmania said scientific data showed the level of ozone-depleting chlorine in the atmosphere was declining because of the ban on the use of chlorofluorocarbons (CFCs) in fridges and air conditioners, agreed under the Montreal Protocol in 1987.

Dr Paul Fraser, the chief atmospheric research scientist with the Commonwealth Scientific and Industrial Research Organisation, said: "This is big news. We have been waiting for this. We think the trend is definite now. It is very significant."

Dr Fraser said that after the ban was adopted, the atmospheric level of chlorine continued to rise, peaking in 2000. "That was simply due to old refrigerators and old air-conditioners in cars," he says.

Since then, the level had stabilised and was now declining, albeit slowly, Dr Fraser said. He predicted that the hole in the ozone layer would contract steadily from about 2005 and disappear by mid-century, although the ozone would be vulnerable for a decade.

Under the Montreal Protocol, developing countries committed themselves to halving consumption and production of CFCs by 2005 and achieving an 85 per cent cut by 2007. The hole in the ozone layer, which protects Earth from the Sun's ultraviolet rays, was first detected nearly 30 years ago. It was then three times the size of Australia, itself covering nearly 3 million square miles.

澳大利亚一研究小组9月17日向全世界报告了一条好消息：南极洲上空的臭氧层空洞呈现出缩小的趋势，预计到2050年之前，这个巨大空洞就可以完全恢复了。

据塔斯马尼亚的科学家介绍，数据表明在大气层的消耗臭氧物质中，氯的含量正在下降。这应该归功于自1987年通过《蒙特利尔议定书》以来，人们在冰箱和空调设备中对吞噬臭氧的罪魁祸首--氟氯碳化物(CFCs) （一种含有氯、氟、碳三种元素的有机化合物，俗称"氟里昂"）实行了全面的控制。

澳洲科学及工业研究机构（CSIRO）大气研究的主要负责人保罗·弗雷泽博士说："这是个激动人心的消息。我们一直盼望着这一天。毫无疑问现在我们正在朝着这个方向前进，这个意义非比寻常。"

弗雷泽博士还介绍说，即便在控制使用氟里昂后，大气中的氯含量还是在不断攀升，并在2000年达到了顶峰。他说："这主要是由于冰箱和车载空调的普及所造成的。"

直到2000年以后，氯气含量才停止增加并呈现缓慢下降的趋势。弗雷泽博士预测说，臭氧空洞将于2005年开始收缩变小，直到本世纪中期被完全填满，但填满后仍有十年属于比较容易被破坏的过渡期。

根据《蒙特利尔议定书》，到2005年，发展中国家氟里昂产品的消耗量和生产量都将减半，到2007年则减少85%，以此来保护我们的大气层。人们是在约30年前发现这个臭氧层空洞的。而臭氧层的作用主要是保护我们不直接受到太阳的紫外线辐射。30年来，臭氧层的这个空洞面积达到澳大利亚本土面积的3倍。而澳大利亚的本土面积为300万平方英里。