Stephen Rees's blog

Thoughts about the relationships between transport and the urban area it serves

Study Links Ozone Hole to Climate Change

with 3 comments

Text of a Press Release copied below. This does seem important to me – even if it is not exactly about transport and planning in Greater Vancouver. I have left comments and pingbacks open so if people want to opine on this sort of thing getting posted here they can. If you are on the Landwatch list serve you will already have seen it, since I forwarded it there as well. Kudos to the Canadian Centre for Climate Modelling and Analysis in Victoria, BC.


First Time that Ozone Depletion Is Shown to Impact the Entire Circulation of the Southern Hemisphere
New York — April 21, 2011 — In a study to be published in the April 21st 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. While previous work has shown that the ozone hole is changing the atmospheric flow in the high latitudes, the Columbia Engineering paper, “Impact of Polar Ozone Depletion on Subtropical Precipitation,” demonstrates that the ozone hole is able to influence the tropical circulation and increase rainfall at low latitudes in the Southern Hemisphere. This is the first time that ozone depletion, an upper atmospheric phenomenon confined to the polar regions, has been linked to climate change from the Pole to the equator.

“The ozone hole is not even mentioned in the summary for policymakers issued with the last IPCC (Intergovernmental Panel on Climate Change) report,” noted Lorenzo M. Polvani, Professor of Applied Mathematics and of Earth & Environmental Sciences, Senior Research Scientist at the Lamont-Doherty Earth Observatory, and co-author of the paper. “We show in this study that it has large and far-reaching impacts. The ozone hole is a big player in the climate system!”

“It’s really amazing that the ozone hole, located so high up in the atmosphere over Antarctica, can have an impact all the way to the tropics and affect rainfall there — it’s just like a domino effect,” said Sarah Kang, Postdoctoral Research Scientist in Columbia Engineering’s Department of Applied Physics and Applied Mathematics and lead author of the paper.

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. “This could be a real game-changer,” Polvani added.

Located in the Earth’s stratosphere, just above the troposphere (which begins on Earth’s surface), the ozone layer absorbs most of the Sun’s harmful ultraviolet rays. Over the last half-century, widespread use of manmade compounds, especially household and commercial aerosols containing chlorofluorocarbons (CFCs), has significantly and rapidly broken down the ozone layer, to a point where a hole in the Antarctic ozone layer was discovered in the mid 1980s. Thanks to the 1989 Montreal Protocol, now signed by 196 countries, global CFC production has been phased out. As a result, scientists have observed over the past decade that ozone depletion has largely halted and they now expect it to fully reverse, and the ozone hole to close by midcentury.

But, as Polvani has said, “While the ozone hole has been considered as a solved problem, we’re now finding it has caused a great deal of the climate change that’s been observed.” So, even though CFCs are no longer being added to the atmosphere, and the ozone layer will recover in the coming decades, the closing of the ozone hole will have a considerable impact on climate. This shows that through international treaties such as the Montreal Protocol, which has been called the single most successful international agreement to date, human beings are able to make changes to the climate system.

Together with colleagues at the Canadian Centre for Climate Modelling and Analysis in Victoria, BC, Kang and Polvani used two different state-of-the-art climate models to show the ozone hole effect. They first calculated the atmospheric changes in the models produced by creating an ozone hole. They then compared these changes with the ones that have been observed in the last few decades: the close agreement between the models and the observations shows that ozone has likely been responsible for the observed changes in the Southern Hemisphere.

This important new finding was made possible by the international collaboration of the Columbia University scientists with Canadian colleagues. Model results pertaining to rainfall are notoriously difficult to calculate with climate models, and a single model is usually not sufficient to establish credible results. By joining hands and comparing results from two independent models, the scientists obtained solid results.

Kang and Polvani plan next to study extreme precipitation events, which are associated with major floods, mudslides, etc. “We really want to know,” said Kang, “if and how the closing of the ozone hole will affect these.”

This study was funded by a grant from the National Science Foundation.

Written by Stephen Rees

April 21, 2011 at 12:44 pm

3 Responses

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  1. “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. “This could be a real game-changer,” Polvani added.”

    There is a possibility that the well-oiled climate change denial machine could seize on this information and distort it in essays with headlines something like, Ozone Causes Global Warming, Not Fossil Fuels: Keep Buying Cars and Burning Coal.


    April 27, 2011 at 2:35 pm

  2. Most ozone (O3) is the result of lightning and industrial production for numerous beneficial applications—such as air and water cleansing and as a disinfectant in place of chlorine. Despite being generated by our white blood cells and by certain plants, it is short lived and not readily transported because it quickly decays to O2. Small commercial ozone generators are available for sale to consumers. Ozone is harmful to breathing animals, so concentrations in excess of sixty parts per billion should generally be avoided—depending on time of exposure. Nevertheless, when ozone rises to the stratosphere, it forms a layer twenty kilometers thick at between fifteen and thirty-five kilometers above ground that filters out 93-98 percent of the harmful ultraviolet (UV) radiation from the sun.

    Laws requiring the substitution of chlorofluorocarbons (CFCs) by non-ozone-destroying gases have had a beneficial effect in reducing the “hole” in the ozone layer. Since it only has a duration of twenty-two days in the atmosphere, ozone must be constantly replaced—mostly by the sun’s ultraviolet rays reacting with oxygen but also, besides lightning, by our high-voltage electrical grids and motors using carbon brushes. This cycle has its limits so we must avoid destroying the ozone layer that circulates above the earth. There should be more research to learn what other factors impact the supply, destruction, and escape of ozone, without which there can be no life. Without the ozone layer, our farm products would burn up “on the vine,” as would we.

    When a space shuttle or Russian rocket sends supplies and scientists to the space station, each flight destroys ten thousand tons of ozone of the mere three billion tons protecting us. Increased space exploration and potentially huge numbers of flights for Earth-orbital sightseeing and moon tourism bode ill for the maintenance of this fragile layer. Better means of escaping from Earth’s atmosphere will necessitate the development of astounding solutions. We can visualize satellite terminals in stationary orbit above the atmospheric ozone layer from which nuclear-powered spaceships depart to the moon—and to which they might return. Or, we might have to fill tanks with ozone commercially produced on Earth and attach them to a satellite that would slowly release the gas in the orbit of the ozone layer.

    Henry Markant

    February 12, 2013 at 10:05 am

  3. It is surprising when a post this old (nearly two years since it was posted) attracts a comment that is NOT spam. Thank you.

    Ground level ozone can be an issue in the Lower Mainland of BC during the summer months, when the reaction of pollutants released by motor vehicles react in sunlight with chemical compounds that are naturally occurring. This becomes a potential problem due to the funnel effect of the valley, which can create health risks for those out of doors for long periods in places like Hope or Mission – farmworkers in particular. More info is available from Metro Vancouver

    Stephen Rees

    February 12, 2013 at 10:34 am

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