Ozone Hole Will Heal,
Say Scientists
By Mark Henderson - Science Correspondent
The hole in the Southern Hemisphere,s ozone layer will start shrinking within a decade and should close completely in the next 50 years, according to an international panel.
Data unveiled at a conference in Argentina suggest that the global effort to reduce the use of chlorofluorocarbons (CFCs)" the main menace to the ozone layer " is succeeding, just three months after Nasa revealed that the size of the ozone hole in the Southern Hemisphere had grown to 11 million square miles and had reached the tip of South America for the first time.
The recovery should result in a reduction in levels of ultra-violet radiation around the globe. It causes skin cancer and harms plant and marine life.
Data from the Cape Grimm monitoring station in Tasmania show that levels of CFCs in the lower atmosphere are starting to decline for the first time since scientists from the British Antarctic Survey discovered the ozone hole in 1985. A new mathematical model, the most accurate yet devised, suggests that there will be a similar decline in the stratosphere over the next decade, leading to a recovery in levels of ozone.
The dramatic recovery could, however, be slowed by as much as 30 years by global warming or by severe volcanic eruptions, according to the meeting in Argentina of the Stratospheric Processes and their Role in Climate panel, which is a project of the World Climate Programme. It will also depend on continued efforts of the global community to keep ozone emissions low. The hole could also grow slightly over the next five years before recovery begins.
Professor Alan O,Neill, the director of the Centre for Global Atmospheric Modelling, University of Reading, and chair of the panel, said that the news was a "triumph for global co-operation. The success could be attributed to the 1987 Montreal Protocol, in which most governments pledged to reduce their use of CFCs, he said.
The United States has cut its annual ozone output from 306,000 ozone depletion potential tonnes (ODP tonnes) to 2,500. The 12 nations that were then members of the European Union have reduced their use from 301,000 to 4,300 ODP tonnes, while Japan has cut its output from 118,000 ODP tonnes to zero.
The global effort represents a triumph for the British scientists Brian Gardiner, Jonathan Shanklin and Joseph Farman, who alerted the world to the hole in 1985. Their work convinced governments to act.
Professor O,Neill said: "We have now gotthe science of the ozone layer buttoned down, and we can predict with reasonable certainty that it is on the road to recovery. What is happening is that levels of CFCs has been reduced by concerted action. What this shows is that by understanding the science of global environmental problems, we can convince governments to take action to turn things around.
He said that the latest news was a timely warning to governments after the recent collapse of talks in The Hague aimed at agreeing a global response to climate change. The science of global warming was not as well-understood as that of ozone, Profesor O,Neill said.
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