This continues until the stratospheric clouds disappear due to warming of the south polar atmosphere as summer approaches. By summertime, stratospheric air from lower latitudes is able to penetrate the polar latitudes, and thereby replenish the ozone layer above Antarctica. Hence, there is a seasonal cycle to the ozone hole over Antarctica with the lowest ozone levels recorded in late September and early October.
The ozone layer protects life from harmful UV-B radiation which can cause cancer and stunt the growth of plants. As UV radiation can penetrate into the surface of the ocean, marine organisms especially phytoplankton can also be damaged. If there was no ozone layer at all, photosynthesis by plants would be impaired and ecosystems could not function as they do today — so it is clearly in our interest to make sure we do not damage the ozone layer.
In an historic international agreement was signed the Montreal Protocol which came into force in and set deadlines for reducing and eliminating the production and use of ozone depleting substances. It also promotes research and development into finding ozone safe substitute chemicals for the uses to which CFCs, etc. It has since been ratified by countries, has been revised several times, and has been described as one of the most successful international treaties.
Through its various mechanisms, the treaty has brought down worldwide emissions of CFCs and other ozone depleting chemicals sharply. However, due to the long residence time of many of these gases in the atmosphere for example CFC resides in the atmosphere for approximately years , the ozone layer will not fully recover until around Use the text above, and information from any of the links listed, to write your own summary of the ozone hole.
Address the following questions in your summary document:. Suggest some reasons why annual CFC emission is not the only factor affecting October ozone levels. Using the information in both this section and Climate change: past and future , as well as any of the suggested links, write an essay answering this question: Why does tackling the problem of global warming present a bigger challenge to the international community than the problem of the ozone hole?
Skip to content Menu. Sizing up Antarctica The world turned upside down? Measuring the ice Going back in time Antarctica: The frozen continent Oceans, atmosphere, landscape A changing climate Seasonal change The climate today The climate of the past The climate of the future Rising seas Making waves Glaciation So you think you know about glaciers?
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Which view of the future? You decide! Reporting on the future How is Antarctica governed? The Antarctic Treaty All agreed? Climate Ozone Depletion The ozone layer helps to protect life from harmful ultraviolet radiation. Find out what caused the ozone hole, and how the Montreal Protocol sought to put an end to ozone depletion.
Ozone threats and 'the hole' In , Mario Molina and Sherwood Rowland , two chemists at the University of California, Irvine, published an article in Nature detailing threats to the ozone layer from chlorofluorocarbon CFC gases. Share Tweet Email. Read This Next Wild parakeets have taken a liking to London. Animals Wild Cities Wild parakeets have taken a liking to London Love them or hate them, there's no denying their growing numbers have added an explosion of color to the city's streets.
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After several years of effort, the parties agreed on 15 October to amend the Protocol to include control measures to reduce HFCs the Kigali Amendment. A successful HFC phasedown is expected to avoid up to 0. The Vienna Convention, Montreal Protocol and Kigali Amendment create a global policy framework for protecting the ozone layer and the climate.
Implementing those policies has required profound changes in many commercial and technological sectors. Putting policy into practice.
Refrigeration and air conditioning were major users of CFCs. Under the Montreal protocol, CFCs have been completely phased-out. The Kigali amendment is now stimulating a further shift towards low global warming HFCs or alternative coolants, such as hydrocarbons or ammonia. This shift to new coolants has also allowed manufacturers and users to switch to refrigeration and air conditioning systems with more efficient energy use.
In the s, almost all the foams used to insulate buildings, refrigerators etc. The rapid and complete phase-out CFCs in aerosols was one of the most recognised achievements of the Montreal Protocol. However, affordable CFC-free alternatives for all inhaled treatments have been developed and are now available worldwide.
The most potent ODSs controlled under the Protocol - halons - are used in fire protection. Halon production has been phased out since However, one remaining challenge is that halons produced before are still used for fire protection in civil aviation. Methyl bromide is a potent ODS that was previously used widely to control pest and diseases, both during crop production and in food storage.
The Montreal Protocol has stimulated the replacement of methyl bromide with new methods of pest and disease control that are not only ozone-safe, but also safer for operators as well. While we still have work to do there is good news. As of now, 99 per cent of the ozone-depleting substances that are controlled under the Montreal Protocol have been phased out.
They also measure ozone-depleting substances, including some that are not controlled under the Montreal Protocol. The Montreal Protocol is widely lauded as a huge environmental success.
Whilst the damage we have done to the ozone layer has not yet been undone, thanks to this agreement and the collaborative effort of nations around the world, there is scientific evidence that the ozone layer is healing itself and is expected to recover by the middle of this century.
The Montreal Protocol has also considerably reduced climate warming because many ozone-depleting substances are also potent greenhouse gases that contribute to climate forcing when they accumulate in the atmosphere. Montreal Protocol controls have led to a substantial reduction in the emissions of ozone-depleting substances over the last two decades.
These reduction, while protecting the ozone layer, have the additional benefit of reducing the human contribution to climate change. Without Montreal Protocol controls, the climate forcing due to ozone-depleting substances could now be nearly two and a half times the present value. While scientists and researchers find new solutions and create earth-friendly products, there are things we can all do, like buying products that are labeled "ozone friendly" or "HCFC free".
Healing the ozone layer is a major accomplishment, but it also proves something important as we look to the future, how to deal with other global environmental challenges. The message is clear: when people and countries around the world come together, united by a common goal, we can solve seemingly impossible problems.
That is surely a cause for great optimism as we contemplate what else our global community is capable of! Skip to main content. How do these chemicals deplete ozone? Damage to human health and well-being Even with the Montreal Protocol to protect the ozone layer, we should all try to avoid too much exposure to the sun to reduce the risk of disease such as skin cancer and cataracts that are cause by overexposure to UV-B radiation.
The solution In the s, the global community decided to do something about ozone depletion. They help shield our planet from harmful solar radiation. But ozone makes up only one to ten out of every million molecules in the ozone layer. The rest of the molecules are mostly nitrogen and oxygen, like the air we breathe.
There isn't much of it, but ozone is powerful, able to block the most harmful radiation. Ozone absorbs the most energetic wavelengths of ultraviolet light , known as UV-C and UV-B, wavelengths that harm living things.
Oxygen molecules absorb other forms of ultraviolet light, too. Together, ozone and oxygen molecules are able to absorb 95 to When UV light is absorbed by oxygen and ozone, heat is generated, which is why the stratosphere gets warmer with altitude. The ozone layer in the stratosphere shields life on Earth from most UV-B and UV-C, the most harmful varieties of ultraviolet radiation. Credit: NASA. Ozone and oxygen molecules are constantly being formed, destroyed, and reformed in the ozone layer as they are bombarded by ultraviolet radiation UV , which breaks the bonds between atoms, creating free oxygen atoms.
Free oxygen atoms are highly reactive, meaning that they bond easily with other molecules.
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