While the hole over Antarctica has been closing, the protective ozone is thinning at the lower latitudes, where the sunlight is stronger and billions of people live

The ozone layer that protects people from the sun’s ultraviolet radiation is not recovering over most highly populated regions, scientists warned on Tuesday.

The greatest losses in ozone occurred over Antarctica but the hole there has been closing since the chemicals causing the problem were banned by the Montreal protocol. But the ozone layer wraps the entire Earth and new research has revealed it is thinning in the lower stratosphere over the non-polar areas.

Reduced protection from cancer-causing UV rays is especially concerning towards the equator, where sunlight is stronger and billions of people live. The reason for the falling ozone at lower latitudes is not known, though scientists suspect a chemical used in paint stripper and a change in atmospheric circulation caused by climate change.

“The study is in lower to mid latitudes, where the sunshine is more intense, so that is not a good signal for skin cancer,” said Prof Joanna Haigh at Imperial College London, a member of the international research team. “It is a worry. Although the Montreal protocol has done what we wanted it to do in the upper stratosphere, there are other things going on that we don’t understand.”

Anna Jones, an atmospheric chemist at the British Antarctic Survey and not involved in the new study, said: “To identify what action might be needed to prevent further decreases, it is extremely important to understand what is causing the observed downward trend.” Scientists say budget threats to US satellite monitoring programmes must be reversed.

The new research, published in the journal Atmospheric Chemistry and Physics, carefully combined measurements of atmospheric ozone from 11 different datasets to produce a record of the last 30 years. It looked at ozone levels between the 60th parallels, an area that ranges from Scandinavia, Russia and Alaska in the north to the tip of South America. (London is 51 deg N, Sydney is 34 deg S and New York city is at 41 deg N.)

The stratosphere stretches from 10km above the Earth to 50km and ozone is slowly rising in the upper stratosphere, back towards the levels seen before CFC chemicals caused their damage.

But in the lower stratosphere, when there is the most ozone, levels are falling. Overall, the effects balance out but this means the ozone layer over the area studied is remaining in its depleted state.

The cause of the decline is unknown but might be the result of global warming. Ozone is produced by chemical reactions in the atmosphere over the tropics and then distributed towards the poles world by large air circulation currents. But warming trends could be strengthening these currents, moving more ozone to the poles and leaving less at lower latitudes.

Another suspect is so-called “very short lived substances” (VSLS) - industrial chemicals that destroy ozone. It was thought they broke down too quickly to reach the stratosphere, but that may need to be re-examined.

Ozone hole recovery threatened by rise of paint stripper chemical Read more

Research published in July by Ryan Hossaini, at Lancaster University, UK, and colleagues showed that levels of a key VSLS, called dicholoromethane and used in paint stripper and aerosol sprays, have doubled in the last decade. It is not banned by the Montreal protocol and little is known about where it is leaking from or why emissions have risen so rapidly.

William Ball, an atmospheric scientist at ETH Zurich university in Switzerland, who led the new research, said: “The finding of declining low-latitude ozone is surprising, since our current best atmospheric circulation models do not predict this effect. Very short-lived substances could be the missing factor in these models.”

Hossaini welcomed the “important” new study, but he argues that the current concentrations of VSLS in the atmosphere are too low to explain the falling ozone in the lower stratosphere.

“This work clearly highlights there are still unanswered questions regarding the drivers of long-term changes in stratospheric ozone,” he said. “The implications of the downward ozone trend from the perspective of surface UV and health need to be evaluated as a pressing matter.”</s>The ozone "hole" area above Antarctica, as of February 3rd 2018. The green and blue hues indicate between 200-300 Dobson units, or total ozone(Credit: NASA Ozone Watch)

Despite recent good news concerning the recovery of the ozone layer, a new study has revealed that ozone levels in the heavily populated lower latitudes don't seem to be recovering as well as regions near the poles. Although there isn't yet a clear explanation as to why this is happening, blame may still rest on short-lived ozone-destroying chemicals, such as those found in paint strippers and degreasing agents.



The ozone layer acts as a protective barrier between us and harmful UV radiation emitted from the Sun. In the 1970s, it was discovered that chloroflurocarbons (CFCs) used in refrigeration and aerosols were the main cause of ozone reduction in the stratosphere, eventually leading to their phase out under the Montreal Protocol in 1987.

While this means the ozone "hole" that formed over Antarctica is on its way to recovery, the bottom part of the ozone layer over latitudes from 60° N to 60° S is showing no signs of healing. These latitudes cover heavily populated areas spanning from Russia all the way to the Southern Ocean below Australia.

"The potential for harm in lower latitudes may actually be worse than at the poles," says co-author Joanna Haigh, Co-Director of the Grantham Institute at Imperial College London. "The decreases in ozone are less than we saw at the poles before the Montreal Protocol was enacted, but UV radiation is more intense in these regions and more people live there."

Using new algorithms to merge data from various satellite missions conducted since 1985, the team created a long time series that revealed a longer term trend of ozone decrease at lower latitudes and altitudes in the stratosphere between 10 and 50 km (6.2 to 31 mi). Although they currently can't provide any definitive reason for this, the researchers have proposed a couple of theories.

One is that a shift in atmospheric circulation patterns caused by climate change may be carrying more ozone away from the tropics. Another is that very short-lived substances (VSLSs), that were not thought to stay in the atmosphere long enough to reach the stratosphere and affect the ozone layer, may be hanging around longer than expected.

"The finding of declining low-latitude ozone is surprising, since our current best atmospheric circulation models do not predict this effect," says William Ball from ETH Zurich and PMOD/WRC Davos. "Very short-lived substances could be the missing factor in these models."

Ian Lowe, Emeritus professor at Griffith University, says that although the amount of ozone-depleting substances has been reduced dramatically, it has not yet reached zero.

"Since we have known for more than forty years that a group of chemicals weakens the ozone layer, which protects all life from damaging ultra-violet radiation, phasing these chemicals out completely should be a high priority," Lowe says.

The team's paper can be found in the European Geosciences Union journal, Atmospheric Chemistry and Physics.</s>The ozone layer has recovered at the poles, but the lower stratospheric ozone over the most populated latitudes has declined, according to a study published on Tuesday in the scientific journal Atmospheric Chemistry and Physics.

An international team headed by ETH Zurich University and the Physikalisch-Meteorologisches Observatorium Davos, have discovered that despite the ban on chlorofluorocarbons (CFCs), the concentration of ozone in the lower part of the stratosphere has continued to decline.</s>My attention was captured by the same story posted earlier: “Ozone at lower latitudes is not recovering, despite Antarctic ozone hole healing“.

Here’s the thing, even more interesting — Sometimes the science news cycle throws up interesting juxtapositions. That story appeared as one half of an interesting pair which both appeared in my email inbox today.

“Reduced energy from the sun might occur by mid-century—now, scientists know by how much“ — over at Tallbloke’s place — features the illustration of the solar cycle at the left and refers to a story at Phys.org by the same title. [More on this further on.]

The other bit of Science News came from the journal Science in the most recent Science News email alert pointing me to this article: “Disturbing losses of protective ozone near Earth’s equator may be tied to short-lived chemicals”. This second item contains this image from NASA Goddard —

— which shows a band of lowered concentration of stratospheric ozone girdling the Earth over the tropics. We are informed that “new findings suggest that at mid-latitudes, where most people live, the ozone layer in the lower stratosphere is growing more tenuous—for reasons that scientists are struggling to fathom.”

By “more tenuous”, they mean specifically that “that ozone in the lower stratosphere between 60°S and 60°N has indeed continued to decline since 1998.”

The finding comes from a paper in Atmospheric Chemistry and Physics authored by William Ball and a host of others titled “Evidence for a continuous decline in lower stratospheric ozone offsetting ozone layer recovery”. The general thrust of the paper is that while the “ozone hole” has seen improvement, the ozone layer’s total thickness in the mid-latitudes is declining and Ball and his colleagues suspect that the culprit is “very short-lived substances” (VSLSs): ozone-eating chemicals such as dichloromethane that break down within 6 months after escaping into the atmosphere.” Many of the “VSLSs are of natural origin—marine organisms produce dibromomethane, for example—use of human-made dichloromethane, an ingredient in solvents and paint removers, has doubled in recent years.”

Now we have something new to worry about — yet another human-caused threat to health and safety — maybe an ingredient in paint thinners is causing a dangerous thinning of the protective ozone layer where most of us live.

On the Other Hand —

Over at Phys.org, solar scientists are carefully explaining what is happening with the Sun. Bascially:

“The sun might emit less radiation by mid-century, giving planet Earth a chance to warm a bit more slowly but not halt the trend of human-induced climate change.

 The cooldown would be the result of what scientists call a grand minimum, a periodic event during which the sun’s magnetism diminishes, sunspots form infrequently, and less ultraviolet radiation makes it to the surface of the planet. Scientists believe that the event is triggered at irregular intervals by random fluctuations related to the sun’s magnetic field.”

Well, that’s good news — the cool down of the Sun might save us from [cue scary music] Climate Change.

They also tell us this interesting little fact:

“The reduced energy from the sun sets into motion a sequence of events on Earth beginning with a thinning of the stratospheric ozone layer. That thinning in turn changes the temperature structure of the stratosphere, which then changes the dynamics of the lower atmosphere, especially wind and weather patterns. The cooling is not uniform. While areas of Europe chilled during the Maunder Minimum, other areas such as Alaska and southern Greenland warmed correspondingly.“

Have we seen “reduced energy from the sun”? I don’t know….maybe you do, but we do know that the Solar Cycle looks like this:

Could the thinning of stratospheric ozone in the Tropics be related to the reduced energy from the sun?

This is just a note about two interesting papers appearing simultaneously. I don’t really have any opinion on the matter and am not very knowledgeable about either subject — the Sun or the Ozone Layer — so won’t be able to answer very many [any?] of your questions.

I’m interested in following the discussion in the comments.</s>The ozone layer – which protects us from harmful ultraviolet radiation – is recovering at the poles, but unexpected decreases in part of the atmosphere may be preventing recovery at lower latitudes.

Global ozone has been declining since the 1970s owing to certain man-made chemicals. Since these were banned, parts of the layer have been recovering, particularly at the poles.

However, the new result, published today in the European Geosciences Union journal Atmospheric Chemistry and Physics, finds that the bottom part of the ozone layer at more populated latitudes is not recovering. The cause is currently unknown.

Ozone is a substance that forms in the stratosphere – the region of the atmosphere between about 10 and 50 km altitude, above the troposphere that we live in. It is produced in tropical latitudes and distributed around the globe.

A large portion of the resulting ozone layer resides in the lower part of the stratosphere. The ozone layer absorbs much of the UV radiation from the Sun, which, if it reaches the Earth’s surface, can cause damage to DNA in plants, animals and humans.

In the 1970s, it was recognised that chemicals called CFCs, used for example in refrigeration and aerosols, were destroying ozone in the stratosphere. The effect was worst in the Antarctic, where an ozone ‘hole’ formed.

In 1987, the Montreal Protocol was agreed, which led to the phase-out of CFCs and, recently, the first signs of recovery of the Antarctic ozone layer. The upper stratosphere at lower latitudes is also showing clear signs of recovery, proving the Montreal Protocol is working well.

However, despite this success, scientists have today revealed that stratospheric ozone is likely not recovering at lower latitudes, between 60?N and 60?S (London is at 51?N), due to unexpected decreases in ozone in the lower part of the stratosphere.

Study co-author Professor Joanna Haigh, Co-Director of the Grantham Institute for Climate Change and the Environment at Imperial College London, said: “Ozone has been seriously declining globally since the 1980s, but while the banning of CFCs is leading to a recovery at the poles, the same does not appear to be true for the lower latitudes.

“The potential for harm in lower latitudes may actually be worse than at the poles. The decreases in ozone are less than we saw at the poles before the Montreal Protocol was enacted, but UV radiation is more intense in these regions and more people live there.”

The cause of this decline is not certain, although the authors suggest a couple of possibilities. One is that climate change is altering the pattern of atmospheric circulation, causing more ozone to be carried away from the tropics.

The other possibility is that very short-lived substances (VSLSs), which contain chlorine and bromine, could be destroying ozone in the lower stratosphere. VSLSs include chemicals used as solvents, paint strippers, and as degreasing agents. One is even used in the production of an ozone-friendly replacement for CFCs.

Dr William Ball from ETH Zurich and PMOD/WRC Davos, who led the analysis, said: “The finding of declining low-latitude ozone is surprising, since our current best atmospheric circulation models do not predict this effect. Very short-lived substances could be the missing factor in these models.”

It was thought that very short-lived substances would not persist long enough in the atmosphere to reach the height of the stratosphere and affect ozone, but more research may be needed.

To conduct the analysis, the team developed new algorithms to combine the efforts of multiple international teams that have worked to connect data from different satellite missions since 1985 and create a robust, long time series.

Dr Ball said: “The study is an example of the concerted international effort to monitor and understand what is happening with the ozone layer; many people and organisations prepared the underlying data, without which the analysis would not have been possible.”

Although individual datasets had previously hinted at a decline, the application of advanced merging techniques and time series analysis has revealed a longer term trend of ozone decrease in the stratosphere at lower altitudes and latitudes.

The researchers say the focus now should be on getting more precise data on the ozone decline, and determining what the cause most likely is, for example by looking for the presence of VSLSs in the stratosphere.

Dr Justin Alsing from the Flatiron Institute in New York, who took on a major role in developing and implementing the statistical technique used to combine the data, said: “This research was only possible because of a great deal of cross-disciplinary collaboration. My field is normally cosmology, but the technique we developed can be used in any science looking at complex datasets.”

The paper: ‘Evidence for a continuous decline in lower stratospheric ozone offsetting ozone layer recovery’ by William T. Ball et al. is published in Atmospheric Chemistry and Physics.</s>The ozone layer that protects us from harmful ultraviolet radiation continues to thin over populated areas of the world, a new study warns.

Scientists say the layer is in better shape, however, over the North and South Poles.

Ozone has been declining globally since the 1980s. While the banning of the chloroflourocarbons that cause the thinning is leading to a recovery at the poles, "the same does not appear to be true for the lower latitudes," study author Joanna Haigh of Imperial College in London said.

Located in the stratosphere, the ozone layer blocks potentially harmful ultraviolet energy from reaching our planet's surface. Without it, humans and animals could experience increased rates of skin cancer and other ailments.

Scientists first discovered the dramatic thinning in Earth's protective sheet in the 1970s and determined the production of chlorofluorocarbons (CFCs), used in refrigerators and aerosol sprays, caused the anomaly. The infamous ozone hole over Antarctica was discovered in the late 1970s.

In the late 1980s, 196 countries signed the Montreal Protocol, a treaty that limited production of CFCs around the world.

The cause of the ongoing thinning is unclear, although the study authors suggest a couple of possibilities. One is that climate change is altering the pattern of atmospheric circulation, causing more ozone to be carried away from the tropics.

Another cause could be newer man-made gases that are chewing away at the ozone layer. The gases in question are known as "very short-lived substances" such as dichloromethane, which is used in a variety of industrial processes.

The naturally occurring ozone high up in the atmosphere is the so-called "good ozone" and is in contrast to the "bad ozone" near the surface, which is pollution and can cause respiratory problems.

"The potential for harm in lower latitudes may actually be worse than at the poles," Haigh said. "The decreases in ozone are less than we saw at the poles before the Montreal Protocol was enacted, but UV radiation is more intense in these regions and more people live there."

The study was published in the European Geosciences Union journal Atmospheric Chemistry and Physics.</s>Hopes the ozone layer is recovering have been dashed by new research showing it continues to decline in the most populated areas of the world.

Ozone levels have shown signs of recovery around the poles since efforts in the 1980s to curb the use of damaging chemicals.

But scientists have now discovered the ozone layer - a substance which absorbs UV radiation from the sun - is failing to recover at lower latitudes where the majority of people live.

This could place billions of people at risk of being exposed to increasingly powerful cancer-causing UV rays, especially towards the equator, where sunlight is stronger.

Researchers aren't sure why the ozone layer is declining, but they suggest climate change and short-lived substances (VSLSs) from industrial chemicals could be to blame.

Study co-author Professor Joanna Haigh, Co-Director of the Grantham Institute for Climate Change and the Environment at Imperial College London, said: 'Ozone has been seriously declining globally since the 1980s.

'But while the banning of CFCs is leading to a recovery at the poles, the same does not appear to be true for the lower latitudes.

'The potential for harm in lower latitudes may actually be worse than at the poles', she said.

The ozone forms at tropical latitudes of the stratosphere, which is the region of the atmosphere between six and 31 miles (10km and 50km) altitude, before spreading around the globe.

'The decreases in ozone are less than we saw at the poles before the Montreal Protocol was enacted, but UV radiation is more intense in these regions and more people live there', said Dr Haigh.

The Montreal Protocol was agreed in 1987 to phase out damaging CFC chemicals, used in everything from aerosols to refrigerators.

Studies have shown clear signs of recovery around the Antarctic, where an ozone 'hole' had formed, and elsewhere.

But the new study, published in Atmospheric Chemistry and Physics, found it is likely not recovering at latitudes between 60°N and 60°S (London is at 51°N).

The cause is not certain but the researchers believe it is possible climate change is altering the pattern of atmospheric circulation - causing more ozone to be carried away from the tropics.

They say another possibility is that very short-lived substances (VSLSs), which contain chlorine and bromine, could be destroying ozone in the lower stratosphere.

VSLSs include chemicals used as solvents, paint strippers, and as degreasing agents.

One is even used in the production of an ozone-friendly replacement for CFCs.

Dr William Ball, who led the analysis, said: 'The finding of declining low-latitude ozone is surprising, since our current best atmospheric circulation models do not predict this effect.

'Very short-lived substances could be the missing factor in these models.'

To conduct the analysis the team developed new algorithms to combine the efforts of multiple international teams who have worked to connect data from different satellite missions since 1985.

They used the data to 'create a robust, long time series'.

Dr Ball added: 'The study is an example of the concerted international effort to monitor and understand what is happening with the ozone layer; many people and organisations prepared the underlying data, without which the analysis would not have been possible.'

A hole in the ozone layer that appeared above Antarctica in the 1980s has shrunk thanks to a worldwide ban on chemicals, Nasa has confirmed. Ozone depletion varies with the weather making changes over time difficult to study. Purple and blue shows areas with the least ozone

Although individual datasets had previously hinted at a decline, the application of advanced merging techniques and time series analysis revealed a longer-term trend of ozone decrease in the stratosphere at lower altitudes and latitudes.

Researchers say the focus now should be on getting more precise data on the ozone decline.

They also say it is important to determine what the cause most likely is, for example by looking for the presence of VSLSs in the stratosphere.

Dr Justin Alsing, who worked on the statistical technique of the study, said: 'This research was only possible because of a great deal of cross-disciplinary collaboration.

'My field is normally cosmology, but the technique we developed can be used in any science looking at complex datasets.'</s>The ozone layer is not healing as scientists had hoped. In fact, depressing research released on Tuesday finds our UV-blocking ozone layer is still thinning in more populated parts of the world.

A global effort to cut certain airborne pollutants over the last three decades has been credited with allowing our damaged ozone layer to recover. But the shock new findings – which scientists cannot explain – suggest we may have been celebrating too early.

"This study is scary,” said Professor Bill Laurance, a climate change scientist at James Cook University.

“Until we understand what’s really happening you’d be silly to sun yourself, except in polar regions. The era of suntanning could be over; we might be entering the age of the unfailing sunburn."

The ozone layer is crucial to life on Earth. It blocks the sun’s most damaging rays, preventing them from damaging our DNA.

In the ‘70s, we discovered that chlorofluorocarbons – a type of gas used in fridges and aerosol sprays – were destroying the ozone layer, leading to a large hole forming over the Antarctic.

Humanity responded to the crisis, signing the Montreal Protocol in 1987 and phasing out chlorofluorocarbons.

It was the world’s first universal agreement to cooperate on human health, according to University of Melbourne sustainability expert Dr Paul Read, and heralded huge optimism about how we would respond to other worldwide challenges, such as global warming.

It also seemed to work – the hole over the Antarctic has been gradually closing. Scientists hailed it as the only environmental indicator we had managed to significantly improve since 1992.

A study published on Tuesday by a team of researchers from the UK and Switzerland, published in Atmospheric Chemistry and Physics, challenges that.

The researchers found the parts of the ozone layer that stretch over large swathes of the far north and south of the globe – including the southern ocean below Australia – are not recovering at all. There, the ozone layer is continuing to thin.

“The potential for harm in lower latitudes may actually be worse than at the poles. The decreases in ozone are less than we saw at the poles before the Montreal Protocol was enacted, but UV radiation is more intense in these regions and more people live there,” said study co-author Joanna Haigh, Co-Director of the Grantham Institute at Imperial College London.

What this new paper is saying,” said Dr Read, “is that the hole in the ozone layer, predicted to be completely repaired by around 2060, has a whole section that's not repairing itself.”

The finding comes from a huge project to combine data from multiple atmosphere-monitoring satellite missions since 1985. Adding the data together produced a clear finding the layer was continuing to thin.

It is not clear why these parts of the layer are thinning. The study’s authors suggest climate change may be changing patterns of atmospheric circulation, leading to ozone being distributed differently.

There are also a range of other substances that are used in paint strippers and similar chemicals that could be destroying the ozone. It was previously not believed these substances lasted long enough in the atmosphere to damage the layer.</s>The planet’s natural protection from UV radiation may be in danger over some of the world’s most populous areas.

Backstory: Huge ozone loss hit Earth in the 1980s, especially above Antarctica. The Montreal Protocol banned the chemicals that were responsible for the depletion, and ozone levels in the upper stratosphere grew again.

What’s new: In a paper published in Atmospheric Chemistry and Physics, researchers explain that the ozone in the lower stratosphere is now thinning at lower latitudes. Near the equator, where billions of people live and sunlight is at its most intense, the resulting loss of UV protection could be a disaster.

What’s causing it? That’s still unclear. It may be that changes in atmospheric circulation due to global warming are shifting ozone toward the poles. Or some industrial chemicals once thought to safely break down in the lower atmosphere may, in fact, make their way high enough to account for the damage.</s>Ozone is a molecule comprised of three oxygen atoms that occurs naturally in small amounts.

In the stratosphere, roughly seven to 25 miles above Earth's surface, the ozone layer acts like sunscreen, shielding the planet from potentially harmful ultraviolet radiation that can cause skin cancer and cataracts, suppress immune systems and also damage plants.

It is produced in tropical latitudes and distributed around the globe.

Closer to the ground, ozone can also be created by photochemical reactions between the sun and pollution from vehicle emissions and other sources, forming harmful smog.

Although warmer-than-average stratospheric weather conditions have reduced ozone depletion during the past two years, the current ozone hole area is still large compared to the 1980s, when the depletion of the ozone layer above Antarctica was first detected.

This is because levels of ozone-depleting substances like chlorine and bromine remain high enough to produce significant ozone loss.

In the 1970s, it was recognised that chemicals called CFCs, used for example in refrigeration and aerosols, were destroying ozone in the stratosphere.

In 1987, the Montreal Protocol was agreed, which led to the phase-out of CFCs and, recently, the first signs of recovery of the Antarctic ozone layer.

The upper stratosphere at lower latitudes is also showing clear signs of recovery, proving the Montreal Protocol is working well.

But the new study, published in Atmospheric Chemistry and Physics, found it is likely not recovering at latitudes between 60°N and 60°S (London is at 51°N).

The cause is not certain but the researchers believe it is possible climate change is altering the pattern of atmospheric circulation - causing more ozone to be carried away from the tropics.

They say another possibility is that very short-lived substances (VSLSs), which contain chlorine and bromine, could be destroying ozone in the lower stratosphere.

VSLSs include chemicals used as solvents, paint strippers, and as degreasing agents.

One is even used in the production of an ozone-friendly replacement for CFCs.
Scientists (in the article published in the journal Atmospheric Chemistry and Physics) warn that the ozone layer that protects people from the sun's ultraviolet radiation is recovering only over less populated areas.