This article has been prompted by a copy and paste of a press release at WUWT, and the reaction to it. The NASA press release is about how the hole in the ozone layer over Antarctica is not yet showing any signs of recovery. Since the 1990s it has stopped growing but there is not yet any sign of recovery. AFAIK, this is not unexpected, given the long-lived nature of CFCs. The research is useful in that it explores the situation in much more detail than has been done before now. (Anthony Watts didn't link to the actual press release as usual. I don't know why he doesn't. However he did link to the Ozone Hole Watch website of NASA, which is really good.)
Click here for the archived WUWT article.
The ozone hole should shrink measurably after the mid 2030s
The article is about research by Susan Strahan and Natalya Kramarova (reported at the AGU Fall Meeting), uncovering the complexity of the ozone hole over Antarctica. Wind in the upper atmosphere is moving the ozone around. From the NASA press release:
This work shows that the severity of the ozone hole as measured by the classic total column measurements does not reveal the significant year-to-year variations in the two factors that control ozone: the winds that bring ozone to the Antarctic and the chemical loss due to chlorine.
Until chlorine levels in the lower stratosphere decline below the early 1990s level – expected sometime after 2015 but likely by 2030 – temperature and winds will continue to dictate the variable area of the hole in any given year. Not until after the mid 2030s will the decline stratospheric chlorine be the primary factor in the decline of ozone hole area.
"We are still in the period where small changes in chlorine do not affect the area of the ozone hole, which is why it's too soon to say the ozone hole is recovering," Strahan said. "We're going into a period of large variability and there will be bumps in the road before we can identify a clear recovery."
Full recovery by 2070
Based on the slide presentation from Anne Douglass, Natalya Kramarova and Susan Strahan, after around 2035 the ozone holes should be smaller than they are today, although in the intervening years there will be some holes that are smaller than others. By around 2070 there should be full recovery.
Ozone hole science - a simple view
Jeff Masters at Wunderground has a good summary of the history of the science and response to finding the hole in the ozone layer. He also describes the tactics used by "ozone hole deniers".
Way back in the 1970s, scientists warned that chlorofluorocarbons (CFCs) could cause serious harm to the ozone layer. The hole was first observed in 1985 and prompted immediate attention, resulting in the Montreal Protocol which came into force in 1989.
Most ozone (around 90%) is in the stratosphere. It acts as a UV shield. There are oxygen reactions in the stratosphere that absorb UV and require O3 to do so. Until we began to add CFCs to the air, ozone was constantly being formed and destroyed with these reactions in balance:
CFCs in the stratosphere have their chlorine atoms split off, which then react with ozone, producing O2 and reducing the amount of ozone. This upsets the balance. With less ozone more UV gets through to the surface.
There is a simple explanation of the reactions on the Bureau of Meteorology website here - with diagrams and an animation.
The ozone hole and climate
The ozone hole doesn't just cause damaging UV radiation to get to the surface, as David Karoly explains, it's also affecting the wind winds in the upper atmosphere over Antarctica and thereby affecting southern currents. It therefore has an indirect impact on climate. Where I live in south eastern Australia, the climate is being affected by CO2 warming as well as by shifts in climate zones as a result of the ozone hole over Antarctica. It is making much of Antarctica colder than it would otherwise be but warming the Antarctic Peninsula. It's also probably a contributing factor to sea ice around Antarctica. (Does this mean that the land ice in Antarctica will melt faster when the ozone hole mends? I don't know the answer to that.)
Here's a diagram from the article by David Karoly.
The climate system is complex, meaning that the ozone hole does indirectly alter the surface temperature and climate of the Earth.
Source: The Conversation
Credit: WMO/UNEP Scientific Assessment of Ozone Depletion 2010
From the WUWT comments, with a preamble
Climate science deniers reject climate science relating to human emissions of carbon dioxide. They have a tendency to reject any science that finds that human activity is having an impact.
Today at WUWT, many science deniers are rejecting the well-established science explaining the hole in the ozone layer.
This highlights the "reasoning" of science deniers. For many of them I imagine that when they face any problem, not just a huge problem faced by all of humanity, their first reaction is: "it wasn't my fault". The first reaction of a mature person, by contrast, would be "Let's fix it" or "What can I do to help fix it".
That's why I view science deniers as being basically self-centred, immature, instant gratification-seeking sooks. I don't see different views about climate science as primarily an ideological divide. I think the divide is one of character and maturity. Personal maturity is a bigger indicator of a reaction to problems than education, intelligence or ideology. I don't know if there have been studies that show this. It might even be that emotional maturity is not correlated with acceptance that there is a problem. It could be that it is correlated with the reaction to the problem, regardless of whether the problem is accepted as real or not.
Whatever - science deniers at WUWT are a distinctly immature lot in this regard as you can see from the comments below. Interestingly, the illiterates at WUWT don't deny the holes in the ozone layer, they just deny what's caused them. A bit like how many (most?) of them don't deny that CO2 has increased hugely, they just deny the greenhouse effect or the extent of it.
December 11, 2013 at 3:29 pm
Or CFCs were not the primary driver of the OBSERVED ozone hole: meaning that even without CFCs, there would still be a significantly large hole in the ozone layer. CFCs could make an ozone hole worse, but no-CFCs won’t make the hole completely collapse.
Like CO2 and the thermal regulation of the planet, the assumption is that CFCs control the size of the Antarctic ozone hole. Why? Because “we” don’t have any other idea about what might cause large variations in its size.
The obsessive drive for a Unique Solution is everywhere politicians, scientists and laymen want or need simple solutions easily and cheaply put in-place.
December 11, 2013 at 3:35 pm
There was a multinational that did very well out of this scam, but its name eludes me.
scarletmacaw combines the two and says "scientists don't know nuffin'" and "it's a conspiracy":
December 11, 2013 at 3:41 pm
Chlorine in the atmosphere has natural sources. The ocean releases far more chlorine into the atmosphere than CFCs. It was always about control, never about science.
Brian H makes an irrelevant and meaningless comment and says:
December 11, 2013 at 3:43 pm
All based on another failed presumption of attribution.
Jimbo, like a lot of WUWT-ers asks (excerpt):
December 11, 2013 at 4:02 pm
Is it just possible that the Ozone hole has always been there?
So does Quinn who says (excerpt):
December 11, 2013 at 4:21 pmAnswer: No. It's not possible that the ozone hole has always been there, regardless of how little Jimbo and Quinn know.
The first satellites that specifically went looking for ozone depletion found the hole, but for all we know the hole has been there for hundreds, thousands, or millions of years or longer. As far as I know, there is no conclusive data indicating that the hole was not there prior to the widespread use of CFC’s.
William Mason is ignorant of the fact that the hole has stopped growing as a result of our actions, and that CFCs are long-lived and that the hole is acting on the time frame expected and says:
December 11, 2013 at 4:30 pm
If you suspect that something is causing a problem and you apply the fix for that but somehow it doesn’t cause a recovery would you at some point conclude that you were mistaken about the cause in the first place? Why do they stick to their original theories so adamantly? I think it’s time to reevaluate.
There is more of the same at WUWT - boring, boring same old scientific ilterati nonsense as you'll find on global warming topics at WUWT. (Archived here.)