New research has identified clear signs that the hole in the Antarctic ozone layer is beginning to close.
Scientists from the University of Leeds were part of an international team led by Professor Susan Solomon of the Massachusetts Institute of Technology to confirm the first signs of healing of the ozone layer, which shields life on Earth from the sun’s harmful ultraviolet rays.
Recovery of the hole has varied from year to year, due in part to the effects of volcanic eruptions.
But accounting for the effects of these eruptions allowed the team to show that the ozone hole is healing, and they see no reason why the ozone hole should not close permanently by the middle of this century.
These encouraging new findings, published today in the journal Science, show that the average size of the ozone hole each September has shrunk by more than 1.7 million square miles since 2000 — about 18 times the area of the United Kingdom.
The research attributes this improvement to the 1987 Montreal Protocol, which heralded a ban the use of chlorofluorocarbons (CFCs) — then widely used in cooling appliances and aerosol cans.
Professor Solomon said: “We can now be confident that the things we’ve done have put the planet on a path to heal. We decided collectively, as a world, ‘Let’s get rid of these molecules’. We got rid of them, and now we’re seeing the planet respond.” Co-author Dr Ryan R Neely III, a Lecturer in Observational Atmospheric Science at Leeds, said: “Observations and computer models agree; healing of the Antarctic ozone has begun. We were also able to quantify the separate impacts of man-made pollutants, changes in temperature and winds, and volcanoes, on the size and magnitude of the Antarctic ozone hole.”
University of Leeds colleague and co-author Dr Anja Schmidt, an Academic Research Fellow in Volcanic Impacts, said: “The Montreal Protocol is a true success story that provided a solution to a global environmental issue.”
She added that the team’s research had shed new light on the part played by recent volcanic eruptions – such as at Calbuco in Chile in 2015 – in Antarctic ozone depletion.
“Despite the ozone layer recovering, there was a very large ozone hole in 2015,” she said. “We were able to show that some recent, rather small volcanic eruptions slightly delayed the recovery of the ozone layer.
“That is because such eruptions are a sporadic source of tiny airborne particles that provide the necessary chemical conditions for the chlorine from CFCs introduced to the atmosphere to react efficiently with ozone in the atmosphere above Antarctica. Thus, volcanic injections of particles cause greater than usual ozone depletion.”
The ozone hole begins growing each year when the sun returns to the South Polar cap from August, and reaches its peak in October – which has traditionally been the main focus for research.
The researchers believed they would get a clearer picture of the effects of chlorine by looking earlier in the year in September, when cold winter temperatures still prevail and the ozone hole is opening up. The team showed that as chlorine levels have decreased, the rate at which the hole opens up in September has slowed down.
Key facts
- Scientists from the British Antarctic Survey discovered in the mid-1980s that the October total ozone was dropping. From then on, scientists worldwide typically tracked ozone depletion using October measurements of Antarctic ozone
- Ozone is sensitive not just to chlorine, but also to temperature and sunlight. Chlorine eats away at ozone, but only if light is present and if the atmosphere is cold enough to create polar stratospheric clouds on which chlorine chemistry can occur
- Measurements have shown that ozone depletion starts each year in late August, as Antarctica emerges from its dark winter, and the hole is fully formed by early October
- The researchers focused on September because chlorine chemistry is firmly in control of the rate at which the hole forms at that time of year, so as chlorine has decreased, the rate of depletion has slowed down
- They tracked the yearly opening of the Antarctic ozone hole each September from 2000 to 2015, analysing ozone measurements taken from weather balloons and satellites, as well as satellite measurements of sulphur dioxide emitted by volcanoes, which can also enhance ozone depletion. And, they tracked meteorological changes, such as temperature and wind, which can shift the ozone hole back and forth.
- They then compared yearly September ozone measurements with computer simulations that predict ozone levels based on the amount of chlorine estimated to be present in the atmosphere from year to year. The researchers found that the ozone hole has declined compared to its peak size in 2000. They further found that this decline matched the model’s predictions, and that more than half the shrinkage was due solely to the reduction in atmospheric chlorine and bromine
- Chlorofluorocarbon chemicals (CFCs) last for up to 100 years in the atmosphere, so it will be many years before they disappear completely
- The reason there is an ozone hole in the Antarctic is that it is the coldest place on Earth — it is so cold that clouds form in the Antarctic stratosphere. Those clouds provide particles, surfaces on which the man-made chlorine from the chlorofluorocarbons reacts. This special chemistry is what makes ozone depletion worse in the Antarctic.
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Further information
Dr Anja Schmidt is an Academic Research Fellow in Volcanic Impacts and Hazards at the University of Leeds’ School of Earth and Environment. Dr Ryan R. Neely III is a Lecturer in Observational Atmospheric Science at the Leeds-based National Centre for Atmospheric Science and Leeds’ School of Earth and Environment.
Scientists from the Atmospheric Chemistry Observations and Modeling (ACOM) Laboratory at National Center for Atmospheric Research in Boulder, Colorado, also worked on the research, which was supported in part by the National Science Foundation and the US Department of Energy.
* The paper, Emergence of Healing in the Antarctic Ozone Layer, is published in Science today.
http://science.sciencemag.org/content/early/2016/06/30/science.aae0061
Abstract
Industrial chlorofluorocarbons that cause ozone depletion have been phased out under the Montreal Protocol. A chemically-driven increase in polar ozone (or “healing”) is expected in response to this historic agreement. Observations and model calculations taken together indicate that the onset of healing of Antarctic ozone loss has now emerged in September. Fingerprints of September healing since 2000 are identified through (i) increases in ozone column amounts, (ii) changes in the vertical profile of ozone concentration, and (iii) decreases in the areal extent of the ozone hole. Along with chemistry, dynamical and temperature changes contribute to the healing, but could represent feedbacks to chemistry. Volcanic eruptions episodically interfere with healing, particularly during 2015 (when a record October ozone hole occurred following the Calbuco eruption).
Here is what the sept-oct max “hole” size has been, from NASA data:
So 2015 was the “biggest evah” ( aka since 1979 ) by a gnat’s dick, a bit like warmest year contests.
However, it has clearly been pretty flat since about 1994, after Mt Pinatubo.
If NASA has actually provide monthly data instead of trying to focus on the annual max ‘hole’ size, there would be more insight into the relevance of those two eruptions.
Yet another of those hiatus things….
Except that the “biggest evah” was in 2006.
One might interpret the above graph to be saying that the two volcanoes started the entire process.
I’d say that would be pushing it a bit on the basis of that graph. There is only one point per year and its for a few weeks of sept-oct.
I’d want to see monthly data to get a clearer look at when changes occurred. In fact my graph is a little inaccurate since the date column given by NASA is just the year integer. This gives the impression that the increase in area is already under way before the eruptions. Plotting with and extra 0.75 years to align to September and it looks a lot more attributable.
I had a doubt because Mt.P was a larger eruption yet the response to El Chichon is stronger. However, Mt.P was quite close to the equator and spread fairly evenly to both hemispheres. El Chichon is much more of a SH event.
So there is prima facea evidence at least to indicate that the increasing ozone hole was indeed mainly caused by volcanoes.
I’d say that would be pushing it a bit just on the basis of that graph ( at least as shown ). There is only one point per year and its for a few weeks of Sept-Oct.
I’d want to see monthly data to get a clearer look at when changes occurred. In fact my graph is a little inaccurate since the date column given by NASA is just the year integer. This gives the impression that the increase in area is already under way before the eruptions. Plotting with and extra 0.75 years to align to September and it looks a lot more attributable.
I had a doubt because Mt.P was a larger eruption yet the response to El Chichon is stronger. However, Mt.P is quite close to the equator and the eruption ejecta spread fairly evenly to both hemispheres. El Chichon is much more of a SH event.
So there is prima facea evidence at least to indicate that the increasing ozone hole was indeed mainly caused by volcanoes.
Here is a modified graph with the dates more accurately reflecting the date at which the annual minimum occurs. There is a notable rise in the 2-3 years following each eruption and a ‘hiatus’ since 1995. Since IPCC claims that CFCs remain in the atmosphere for something of the order of 100 years and the 1990 treaty to years to come into effect, claims that this levelling off is a result of Montreal protocol seems unfounded.
If the Ozone ‘Hole’ is ‘healing’, then it is because the Sun is doing something that makes it come to pass.
It is not because we are using fewer CFCs, less CO2, or less noise. It is time for more funding!!
right on!
The following letter segment shows why ozone regulation has very real economic consequences.
To House Energy and Commerce Committee Chairman Upton and Senate Environment and Public Works Committee Chairman Inhofe:
On behalf of the 60 organizations listed below and the millions of Americans represented, we urge you to take action on the Environmental Protection Agency’s National Ambient Air Quality Standard (NAAQS) for Ozone and to reform the rule making process for ozone and other pollutants regulated under NAAQS. Without changes to the ozone regulation and reform of the rule-making process, economic activity could be brought to a standstill in many areas across the country.
The ozone regulation has questionable benefits, but certain economic costs. Last year, when the EPA lowered the compliant level of ozone from 75 to 70 parts per billion (ppb), it estimated the regulation would cost $1.4 billion annually and admitted the cost of the regulation greatly outweighed the benefits of further ozone reductions. Previous cost estimates by the EPA ranged between $3.4 and $25 billion annually. The only way EPA could justify the regulation was to use questionable co- benefits. In reducing ozone, there may also be benefits from reductions of other pollutants, in this case particulate matter (PM). However, the EPA already has another set of regulations dealing exclusively with PM. Either the EPA has woefully inadequate standards for PM or it is effectively “double counting” the health benefits of PM reductions to justify the ozone regulation.
The EPA had to use questionable co-benefits to justify the regulation because of the tremendous reductions in ozone already achieved. Since 1980, ozone concentrations have fallen by 33%. In many areas across the county, ozone concentrations are nearing background levels – concentrations resulting from natural and non local man-made sources. Before finalizing the current regulation, EPA was considering an ozone standard so strict Yellowstone National Park would have been non-compliant….
Posted on AMAC
Oh the irony of EPA rule making where the left hand forbids ozone creation at ground level and the right hand seeks to prevent its’ destruction at the top of the atmosphere. Hey, bureaucrats…can’t we just call it a wash? The various cfc formulations, Freon, Halon, etc. have, had…, many useful industrial applications with no known substitute. It just gets me how people that haven’t built anything in their lives insist on “100% bans” for very useful products. Not a 95% reduction or a 99.9% reduction; no, no, no, no, it has to be 100%. No more Primatene Mist for sufferers of asthma and the most effective decontamination where it really counts on space shuttles, satellites and aircraft. No, no, no. People that don’t do anything aren’t missing their freedom.
sunspot minima
ozone hole heals?
Well, solar cycle is a obvious thought but on the basis of the NASA data I plotted above I don’t see much sign of an 11y cycle in either direction, unless I’m missing something.
Can you point to evidence of solar min / max in that graph?
This is more than a little off-topic.
It saves the world — peculiar, the hole covers the Antarctic appr. 4 % of the global surface.
It sound like they want to close the story. ¿It is winter? There is a hole.
The issue was the hole’s growth during 80’s – 90’s. Continued growth posed a threat to populated areas in the Southern Hemisphere and an unknown effect on the oceans.
Here is the NASA data with a light 1y low-pass gaussian filter. The El Chichon eruption seems to fit perfectly as causing an exponentially decaying effect increasing the size of the 220 DU “hole”. However, there is rise the pre-dates the Mt Pinatubo eruption ( by more than the spreading effect of the filter ) and considerable fluctuation in the plateau.
It would need a closer look at the smaller but more regional activity in Antarctica and Chilli to see whether this could also account for the annual variaiton or whether this has extra-terrestrial origins.
One thing seems clear it was not the Montreal Protocol which stopped the increase in the ozone barely 3 years after it was signed !!
I keep saying this but only because it’s true. Simply looking at the area of the “hole” is misleading. In the late 1950s the Antarctic ozone layer measured over 300 DU. The hole which appeared in the late 1970s was defined by a layer thinner than 220 DU. The average thickness of the hole in 2015 was around 120 DU and has fallen below 100 DU several times.
Thinning of the ozone layer pre-dates El Chichon. While El Chichon and Pinatubo might have acted as a spur for ozone loss, the before/after longer term rates of thinning were very similar.
what sort of spacial and temporal coverage is there behind you claims of late 1950s the Antarctic ozone layer? Data ??
What metric are you suggesting should be used to assess the “health” of the ozone layer?
Ah, the decline in solar activity kicking in.
Correct!
So many world class atmospheric chemists on this site, dazzling.
In all of these comments I am the only one that actually say why the ozone hole is there with an actually physical mechanism… Amazing…
Hi Brant
I have give you a reasonable explanation here
https://wattsupwiththat.com/2016/07/02/scientists-claim-they-have-observed-first-signs-of-healing-in-the-antarctic-ozone-layer/#comment-2250901
did you check the peroxide content inside the hole and compare it with the peroxide concentration outside the “hole”
https://junkscience.com/2016/06/epa-stacked-ozone-science-panel-with-192-million-worth-of-paid-cronies/
It has always struck me as interesting, when we hear of the high rates of skin cancer rates for people in Australia and New Zealand, that these high rates tend to be for those of European extraction, while those for the indigenous peoples are very low.
This could mean that the suns rays have always been strong in the area because of the naturally occurring ozone holes – locals have had millenniums to adapt, whereas newcomers are disadvantaged accordingly.
@Phil.
https://wattsupwiththat.com/2016/07/02/scientists-claim-they-have-observed-first-signs-of-healing-in-the-antarctic-ozone-layer/comment-page-1/#comment-2253500
@Phil.
so if you don’t know, just say so.
What we do know for sure is that ozone, a component in the air that is monitored at several places NH and SH, is increasing [in both hemispheres]
it would therefore be logical to assume that peroxides and N-oxides are also increasing…..
The reason why this is happening is because with the sun’s polar magnetic field strengths at ultra low strengths, more of the most energetic particles of the sun can escape. We are “lucky| to have an atmosphere protecting us against the most harmful rays of the sun.
Still, now is not a good time in the cycle [of 87 years] to go in the sun without good protection.
We’re talking here about the Antarctic ozone hole and peroxides aren’t a player there. In the stratosphere the relevant compounds are OH and HO2 (odd hydrogen, HOx) which are both very reactive and depend on photolytically generated O atoms for their production. In the winter at the altitudes of the Ozone hole the O concentration is very low when the sun is below the horizon. The photochemical lifetime of hydrogen peroxide in the lower stratosphere is a couple of days and in the mesosphere a few hours.Over South Africa it could contribute but I doubt it. The mechanism of O3 degradation and generation is markedly different over the polar regions than in the rest of the stratosphere. Measurements in the polar stratosphere at altitudes of the ozone hole show very little H2O2(~none) compared with the tropics.