Researchers have developed a new method for assessing the impact of ozone-depleting chemicals released into the atmosphere.-
The ozone layer-sits in the stratosphere - between 15 km and 30 km above the Earth --and provides a shield from some of the sun’s harmful ultraviolet radiation.-
Without this ozone protection, higher levels of ultraviolet radiation would-reach the Earth’s surface and result in an increased-incidence-of skin cancer and eye disease as well as adversely effecting plants and crops.-
Since the late 1980s, an international agreement called the Montreal Protocol -has resulted in the phasing out of ozone-depleting chemicals, particularly chlorofluorocarbons (CFCs) which were used in, for example, refrigeration and air conditioning systems. As a consequence, the hole and thinning that was once seen in the ozone layer has been reducing.-
But the rate at which the ozone layer is being replenished is slow, and recently some renewed, illegal production of CFCs has occurred.-
A team of scientists from the University of Leeds, the National Centre for Atmospheric Science , the National Centre for Earth Observation -and the University of Cambridge has developed a new method-to help regulators more accurately assess the impact of the release of ozone-depleting chemicals-and the effectiveness of ozone layer protection measures.-
The researchers have reported their findings--- Integrated ozone depletion as a metric for ozone recovery ---in the-scientific-journal Nature.-
Known as the Integrated Ozone Depletion (IOD) metric, the new measurement considers three things:-the strength of the emission, how long it will remain in the atmosphere, and how much ozone is chemically destroyed by it.-
Professor Martyn Chipperfield, an atmospheric scientist and Director of the- Institute for Climate and Atmospheric Science -at Leeds,-and one of the authors of the study, said: "For many decades scientists have used a very simple measure of how the ozone layer is recovering. That was useful in many ways but could not deal with widely varying scenarios of emissions of ozone-depleting substances.--
"The new tool will provide a better measure of how the ozone layer is recovering."--
The IOD metric will also enable scientists to estimate the effect of any new illegal or unregulated emissions on the ozone layer.-
Lead author Professor John Pyle, of the National Centre for Atmospheric Science and the University of Cambridge, said-it was time for a new method to assess the state of the ozone layer.-
"Following the Montreal Protocol, we are now in a new phase - assessing the recovery of the ozone layer. -
"This new phase calls for new metrics, like the Integrated Ozone Depletion. Our new metric can measure the impact of emissions - regardless of their size. Using an atmospheric chemistry computer model, we have been able to demonstrate a simple linear relationship between the IOD, the size of the emissions and the chemical lifetimes. -
"So, with knowledge of the lifetimes, it is a simple matter to calculate the IOD, making this an excellent metric both for science and policy."
A new method to assess the health of the ozone layer
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