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The Antarctic ozone hole and climate change: an anniversary worth celebrating

SAVING THE OZONE: Part five in our series exploring the Montreal Protocol on Substances that Deplete the Ozone Layer – dubbed “the world’s most successful environmental agreement” – explores the parallels…

Is there a relationship between the ozone hole over Antarctica and the global climate? AAP/Dean Lewins

SAVING THE OZONE: Part five in our series exploring the Montreal Protocol on Substances that Deplete the Ozone Layer – dubbed “the world’s most successful environmental agreement” – explores the parallels between saving the ozone and fighting climate change.

Since the discovery of the Antarctic ozone hole more than 20 years ago, scientists have shown that there are no direct links between global warming and the ozone hole. They are due to quite different processes associated with human activities - increasing greenhouse gas emissions on one hand and increasing release of ozone-depleting chemicals on the other.

There are a number of common misconceptions about connections between the two, such as the ozone hole allowing more sunshine in to heat the surface and cause global warming. Scientists have tried to combat these misconceptions through more effective communication of the cause of ozone depletion and the cause of global warming.

However, the climate system is very complex, with connections between many different parts. Hence, it should come as no surprise to hear that there are some indirect links between the Antarctic ozone hole and changes in surface weather and climate.

Ozone absorbs solar ultraviolet radiation, warming the stratosphere. The formation of the ozone hole means less UV radiation is absorbed, cooling the stratosphere over Antarctica in spring and summer. This cooling leads to stronger westerly winds in the upper atmosphere, as well as stronger westerly winds in the lower atmosphere in late spring and summer.

The climate system is complex, meaning that the ozone hole does indirectly alter the surface temperature and climate of the Earth. WMO/UNEP Scientific Assessment of Ozone Depletion 2010

These stronger winds encircling Antarctica have a number of impacts on the surface climate. They lead to reduced heat transfer from lower latitudes, making most of Antarctica cooler than it would otherwise have been but warming the Antarctic Peninsula (the part that sticks up towards South America).

They also lead to three other changes: in Southern Ocean currents; in the gas exchanges between the Southern Ocean and the atmosphere; and in the expansion of sea ice extent.

All of these changes have been observed and modelled as responses to the ozone hole, indicating that there really is an indirect link between surface climate change and the Antarctic ozone hole.

There is a second connection between global warming and ozone depletion. Ozone-depleting chemicals are also very potent greenhouse gases. The reduction in emissions of ozone-depleting chemicals due to the establishment of the Montreal Protocol 25 years ago has been substantial. Without this reduction, global warming would have accelerated even more.

In fact, the reduction in greenhouse gases due to the Montreal Protocol is five times larger than the reduction in greenhouse gases achieved through the Kyoto Protocol.

Global emissions of ozone-depleting chemicals (CFCs, halons, HCFCs, and others) and their non-ozone depleting substitutes (HFCs) from 1950 to 2050, expressed as Gigatonnes of CO2-equivalent per year. The blue hatched regions indicate the emissions that would have occurred, in the absence of the Montreal Protocol, with 2–3% annual production increases in all ozone-depleting chemicals. Shown for reference are emissions for the range of CO2 scenarios from the IPCC Special Report on Emission Scenarios. WMO/UNEP Scientific Assessment of Ozone Depletion 2010
The Montreal Protocol was thus not only a very successful international policy agreement addressing ozone depletion, but has also reduced global warming, if only by a small amount.

This is another important reason to celebrate the 25th anniversary of the Montreal Protocol!

Read more on the Montreal Protocol’s 25th anniversary.

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  1. Marc Hendrickx

    Geologist: The Con is a bad Monty Python sketch, for climate sense see: http://www.thegwpf.org/

    David, you write "Since the discovery of the Antarctic ozone hole more than 20 years ago, scientists have shown that there are no direct links between global warming and the ozone hole. " You then spend some part of your essay rebutting your point!

    Can you comment on this recent paper?

    "Study Links Ozone Hole to Broader Climate Change"
    In a study to be published in the April 21 issue of Science magazine, researchers at Columbia University’s School of Engineering and Applied Science report their findings that the ozone hole, which is located over the South Pole, has affected the entire circulation of the Southern Hemisphere all the way to the equator.
    http://engineering.columbia.edu/study-links-ozone-hole-broader-climate-change

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    1. Marc Hendrickx

      Geologist: The Con is a bad Monty Python sketch, for climate sense see: http://www.thegwpf.org/

      In reply to Marc Hendrickx

      From the same press release..."The ozone hole is now widely believed to have been the dominant agent of atmospheric circulation changes in the Southern Hemisphere in the last half century. This means, according to Polvani and Kang, that international agreements about mitigating climate change cannot be confined to dealing with carbon alone— ozone needs to be considered, too."

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    2. Mike Hansen

      Mr.

      In reply to Marc Hendrickx

      Marc.
      Karoly says "there are no direct links between global warming and the ozone hole" followed by "there are some indirect links between the Antarctic ozone hole and changes in surface weather and climate". He then proceeds to discuss those impacts. He even presents a diagram.
      Where does he rebut himself? Did you actually read the article? Or this an exercise in pedantic parsing?
      I am sure you have a point about how we can continue to burn lots of coal which you will get to in due course.

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    3. In reply to Mike Hansen

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    4. In reply to Mike Hansen

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    5. Sean Lamb

      Science Denier

      In reply to Grendelus Malleolus

      I thought ozone was itself an GHG, albeit one normally found in the higher layers, hence a reduction in ozone ought to lead to a reduction of temperature in the stratosphere.

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    6. Mike Hansen

      Mr.

      In reply to Grendelus Malleolus

      In David Karoly's article
      "Ozone absorbs solar ultraviolet radiation, warming the stratosphere. The formation of the ozone hole means less UV radiation is absorbed, cooling the stratosphere over Antarctica in spring and summer."

      http://www.ozonelayer.noaa.gov/science/basics.htm
      "Stratospheric ozone (sometimes referred to as "good ozone") plays a beneficial role by absorbing most of the biologically damaging ultraviolet sunlight (called UV-B), allowing only a small amount to reach the Earth's surface. The absorption of ultraviolet radiation by ozone creates a source of heat, which actually forms the stratosphere itself (a region in which the temperature rises as one goes to higher altitudes). "

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    7. Sean Lamb

      Science Denier

      In reply to Grendelus Malleolus

      Then it is going to play a role in climate change by alterations in the temperature gradient for heat conduction.

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    8. Sean Lamb

      Science Denier

      In reply to Mike Hansen

      Now that is a non sequitur

      I didn't ask about ultraviolet absorption, I asked about GHG activity.

      If a job is worth doing, do it yourself
      http://www.greatians.com/globalwarming/greenhouse%20gas.htm
      Absorption in the 10 micrometer range.
      I never ceased to be amazed how little those who see it a full time job to go round the net spreading the AGW gospel actually know about the subject.

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    9. Sean Lamb

      Science Denier

      In reply to Sean Lamb

      It seems to me that declining ozone will lead to stratophere/troposphere cooling in two ways
      1. trapping UV light coming in
      2. catching a band of IR coming out.
      So ozone decline ought definitely to lead to higher level cooling.

      But ozone decline might lead to surface warming - since the UV light that was normally trapped above is now more likely to reach the surface - although perhaps the UV light that has been let through is not significant enough in terms of climate, after all our skins are probably a fairly sensitive indicator that the increase has not been too great to date.

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    10. Sean Lamb

      Science Denier

      In reply to Mike Hansen

      errr, why should it mention the stratophere?

      I just said ozone absorbs in the IR range - 10 micrometers - hence it is a GHG.
      Instead of just admitting you were wrong you just start throwing around completely irrelevant nonsense and off topic links.
      Its like some AGW proponents seriously have a mental illness.

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    11. Grendelus Malleolus

      Senior Nerd

      In reply to Sean Lamb

      "It seems to me" and then "stratophere/troposphere cooling"

      Why do you think the presence of zone has the same effect on each layer of the atmosphere?

      "although perhaps the UV light that has been let through is not significant enough in terms of climate, after all our skins are probably a fairly sensitive indicator that the increase has not been too great to date."

      You may not feel so, but I recommend reading up on the evidence of prevelance and the modelling that has been done - extensively, on the level of prevelance we have avoided by taking early action on CFCs.

      Particularly:

      Dijk, A et al (2012) Skin cancer risks avoided by the Montreal Protocol–worldwide modelling integrating coupled climate‐chemistry models with a risk model for UV. Photochemistry and photobiology. Pre-Publication e-copy.

      and

      http://www.who.int/globalchange/publications/climatechangechap8.pdf

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    12. Sean Lamb

      Science Denier

      In reply to Grendelus Malleolus

      Suits me - some measurable level of global warming is due to ozone depletion then. I was just taking a standard precautionary scientific approach. I mean what the hell, this is climate science and anything goes.

      I don't see this as a partisan fight, rather of trying to build an accurate understanding. The more warming that is place on other causes, the less that CO2 is a concern.

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    13. Mike Hansen

      Mr.

      In reply to Sean Lamb

      Oh no.

      I have been insulted by a "mocker" who claims that ozone "is going to play a role in climate change by alterations in the temperature gradient for heat conduction" - whatever that means.

      Conduction? This is the giveaway that Sean is just making stuff up.

      "In the climate system, conduction is generally negligible because gases and liquids like water don’t conduct heat well at all."

      "...heat cannot be transferred across a boundary between a surface and a fluid by convection. Conduction is therefore important at the boundary between the earth’s surface and atmosphere."
      http://scienceofdoom.com/2011/01/02/heat-transfer-basics-convection-part-one/

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    14. In reply to Mike Hansen

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    15. David Arthur

      resistance gnome

      In reply to Sean Lamb

      Interesting point Sean. If the stratosphere is letting more energy through to the surface, then it contributes to surface warming ... so according to Sean, this is less warming which can be "blamed" on CO2.

      CO2 is causing as much warming as ever; ozone loss means that UV warming is on top of CO2 warming.

      More significant, however, is the life-destroying effect of increased UV at the surface. While you are free to mock the degradation of the ecosystems that support your life, the word that springs to my mind is 'foolhardy'..

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    16. In reply to Gerard Dean

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    17. In reply to Gerard Dean

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    18. In reply to Sean Lamb

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    19. In reply to Gerard Dean

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    20. In reply to John Nicol

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    1. In reply to Mike Hansen

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    1. In reply to Gerard Dean

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    2. In reply to Gerard Dean

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