30 Years of Satellite Data Reveal Unexpectedly Bad News for the Ozone Layer


In June 2016 scientists announced that there was evidence of the “first fingerprints of healing” in the ozone layer above Earth’s poles. This was great news: We need the ozone layer to absorb UV radiation from the Sun, and holes mean that radiation can pass through and damage the DNA of plants and animals. Closing them up meant we were finally doing something right for the environment.

ozone layer

On Tuesday, however, an international team of researchers scaled back the excitement with a grave announcement in Atmospheric Chemistry and Physics: Despite the progress at the poles, the swath of the ozone layer at lower latitudes — a region covering London, New York City, and Buenos Aires, and many other big cities — is not recovering. This huge stretch of the globe, they write, not only covers the most highly populated regions but also gets the most intense sunshine.

It is “not a good signal for skin cancer,” study co-author and Grantham Institute for Climate Change co-director Joanna Haigh, Ph.D., told The Guardian on Tuesday.

stratosphere
Ozone forms in the stratosphere and we live in the troposphere.

What’s most concerning is that the Haigh and her team don’t really know why recovery is stalling at lower latitudes.

“The finding of declining low-latitude ozone is surprising since our current best atmospheric circulation models do not predict this effect,” co-author William Ball, Ph.D., said in the statement. “Very short-lived substances could be the missing factor in these models.”

The success we’ve had at closing up the ozone holes at the poles has been attributed to the Montreal Protocol, a United Nations agreement passed in 1987 ordering the phase-out of chemicals called CFCs. These chemicals, found in refrigeration systems and aerosols, drift into the stratosphere, release chlorine, and destroy ozone, a highly reactive gas. It’s not clear why these interventions have had more success at the poles than at lower latitudes.

The researchers have some theories: One thing driving the continuous decline in ozone is that climate change is altering the pattern of atmospheric circulation, shifting ozone further away from tropical latitudes. Another possibility is that very short-lived substances (VLS), chemicals that are used as solvents, paint strippers, and degreasing agents, may also be destroying the ozone in the lower stratosphere.

ozone layer
NASA’s prediction for ozone concentration levels. 

The researchers noticed the slowly recovering areas after examining satellite data collected since 1985, which allowed them to create a 30-year record of atmospheric ozone and how it’s been measured over the years. Analysis of the ozone levels between the 60th parallels — as far north as Alaska and as far south as the bottom tip of Argentina — revealed impaired ozone recovery in those regions.

This bodes poorly for us humans, said Haigh, explaining in the statement that “the potential for harm in lower latitudes may actually be worse than at the poles” because in these regions UV radiation is more intense and more people live there.

The next step for the researchers is gathering more precise data on ozone decline and determining exactly what is driving the impaired ozone recovery. They might want to do so sooner rather than later: Budget threats to United States satellites that monitor the changing climate could seriously endanger the progress of their research.

Great News! The Massive Hole In The Ozone Layer Is Finally Healing!


There’s great news for those trying to consciously make an effort to save our environment. According to the researchers from the University of Leeds and Massachusetts Institute of Technology (MIT), the hole in the Antarctic ozone layer is shrinking, and should be completely healed by 2050!

Ozone Layer Healing

 

There is a ray of hope. Finally!

The ozone layer shields the Earth and its inhabitants from the Sun’s harmful ultraviolet rays, and as per the new findings published in the journal Science, the average size of the ozone hole shrunk by more than 1.7 million square miles each September since 2000, which is pretty impressive. Researchers have now predicted that the hole above the South Pole should be completely sealed permanently by 2050.

 
What did we/are we doing right?

It is being said that the positive news is all thanks to the success of the 1987 Montreal Protocol that banned the use of chlorofluorocarbons in aerosols (spray cans) and refrigerators. “We can now be confident that the things we’ve done have put the planet on a path to heal,” said Susan Solomon, a professor at MIT.

Ozone Layer Healing

 

The ozone hole was first noticed by scientists from the British Antarctic survey using ground-based data that began in the 1950s and mid-1980s. The hole kept becoming bigger ever since. But it truly reached an alarming stage in 2000 at 15 million square miles. The hole starts expanding when the Sun returns to the South Polar cap from August and reaches its peak in October. Talking to Telegraph UK, professor Solomon said, “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.”

With this, the Montreal Protocol becomes a fantastic example of how, if we do things right, we can possibly end up saving our dear planet Earth.

New threat to ozone layer identified.


ozone hole
Dealing with the hole in the ozone layer has been one of the most successful international science projects
Sientists have identified four new man-made gases that are contributing to the depletion of the ozone layer.

Two of the gases are accumulating at a rate that is causing concern among researchers.

Worries over the growing ozone hole have seen the production of chlorofluorocarbon (CFC) gases restricted since the mid 1980s.

But the precise origin of these new, similar substances remains a mystery, say scientists.

Lying in the atmosphere, between 15 and 30km above the surface of the Earth, the ozone layer plays a critical role in blocking harmful UV rays, which cause cancers in humans and reproductive problems in animals.

“Start Quote

We don’t know where the new gases are being emitted from and this should be investigated”

Dr Johannes LaubeUniversity of East Anglia

Scientists from the British Antarctic Survey were the first to discover a huge “hole” in the ozone over Antarctica in 1985.

The evidence quickly pointed to CFC gases, which were invented in the 1920s, and were widely used in refrigeration and as aerosol propellants in products like hairsprays and deodorants.

Remarkably, global action was rapidly agreed to tackle CFCs and theMontreal Protocol to limit these substances came into being in 1987.

A total global ban on production came into force in 2010.

Now, researchers from the University of East Anglia have discovered evidence of four new gases that can destroy ozone and are getting into the atmosphere from as yet unidentified sources.

Halley
The Halley Research Station in Antarctica, where the hole in the ozone layer was first discovered

Three of the gases are CFCs and one is a hydrochlorofluorocarbon (HCFC), which can also damage ozone.

“Our research has shown four gases that were not around in the atmosphere at all until the 1960s which suggests they are man-made,” said lead researcher Dr Johannes Laube.

The scientists discovered the gases by analysing polar firm, perennial snow pack. Air extracted from this snow is a natural archive of what was in the atmosphere up to 100 years ago.

Grim discovery

The researchers also looked at modern air samples, collected at remote Cape Grim in Tasmania.

They estimate that about 74,000 tonnes of these gases have been released into the atmosphere. Two of the gases are accumulating at significant rates.

“The identification of these four new gases is very worrying as they will contribute to the destruction of the ozone layer,” said Dr Laube.

“We don’t know where the new gases are being emitted from and this should be investigated. Possible sources include feedstock chemicals for insecticide production and solvents for cleaning electronic components.”

“What’s more, the three CFCs are being destroyed very slowly in the atmosphere – so even if emissions were to stop immediately, they will still be around for many decades to come,” he added.

Continue reading the main story

Mysterious gases

  • The four new gases have been identified as CFC-112, CFC112a, CFC-113a, HCFC-133a
  • CFC-113a has been listed as an “agrochemical intermediate for the manufacture of pyrethroids”, a type of insecticide once widely used in agriculture
  • CFC-113a and HCFC-133a are intermediaries in the production of widely used refrigerants
  • CFC-112 and 112a may have been used in the production of solvents used to clean electrical components

Other scientists acknowledged that while the current concentrations of these gases are small and they don’t present an immediate concern, work would have to be done to identify their origin.

“This paper highlights that ozone depletion is not yet yesterday’s story,” said Prof Piers Forster, from the University of Leeds.

“The concentrations found in this study are tiny. Nevertheless, this paper reminds us we need to be vigilant and continually monitor the atmosphere for even small amounts of these gases creeping up, either through accidental or unplanned emissions.

“Of the four species identified, CFC-113a seems the most worrying as there is a very small but growing emission source somewhere, maybe from agricultural insecticides. We should find it and take it out of production.”

Ozone Hole and The Global Climate Changes.


The release of CFCs or chlorofluorocarbons into the atmosphere through human activities has caused a massive hole in the ozone layer right above Antarctica and if unchecked, melting icecaps may inundate several regions of the earth in the future.

What is Ozone and Where Is It Found in The Earth’s Atmosphere?

Ozone is a gas with a pungent odor whose molecule contains three oxygen atoms. At about 6–10 miles above the Earth’s surface and extending up to 30 miles, in a region of space called the stratosphere, you will find 90% ozone. The stratospheric region with the highest ozone concentration is commonly known as the “ozone layer”. The remaining ozone, about 10%, is found in the troposphere, which is the lowest region of the atmosphere, between Earth’s surface and the stratosphere.

Ozone at ground level in the troposphere is bad because it causes photochemical smog. The smog results when ultra-violet light falls on and reacts with nitrogen oxide from vehicle exhausts. Because of this, Ozone affects lung function, aggravates asthma and other chronic respiratory diseases.

On the other hand, ozone in the stratosphere performs a very useful function by acting as a blanket that blocks most of the sun’s high-frequency ultraviolet rays. These UV rays can cause skin cancer and cataracts in humans, as well as reproductive problems in several forms of life including even the single-celled phytoplankton at the bottom of the ocean food chain.

How Does Ozone Form in the Atmosphere?

When ultraviolet light strikes oxygen molecules containing two oxygen atoms (O2), it splits them into individual oxygen atoms (atomic oxygen), which then combines with unbroken O2 to create ozone, O3. Being unstable, this ozone once again splits into a molecule of O2 and an atom of atomic oxygen under the action of ultraviolet light. This continuing process called the ozone-oxygen cycle.

The ozone layer  is very effective at screening out UV-B; Nevertheless, some UV-B, particularly at its longest wavelengths, reaches the surface. Ozone cannot stop UV-A, the longer wavelength ultraviolet radiation which  reaches the earth’s surface. However, this type of UV radiation is significantly less harmful to DNA.

The thickness of the ozone layer varies widely throughout the world, being smaller near the equator and larger towards the poles. It also varies with season, being in general thicker during the spring and thinner during the autumn in the northern hemisphere.

Ozone ‘Hole’

In May 1985 scientists with the British Antarctic Survey announced the discovery of a huge hole in the ozone layer over Antarctica. They announced that Ozone levels over the northern hemisphere had been dropping by 4% per decade. They described the larger seasonal drops in the ozone levels around the south pole as a ozone hole.

The ozone hole is not technically a “hole” with no ozone is present, but is actually a region of exceptionally depleted ozone in the stratosphere over the Antarctic during the Southern Hemisphere spring (August–October).

Stratospheric temperatures in the Northern Hemisphere during winter/spring are generally slightly warmer than those in the Southern Hemisphere. Therefore ozone losses over the Arctic have been much smaller than over the Antarctic during the 1980s and early 1990s. However, the Arctic stratosphere has gradually cooled over the past few decades, and Ozone holes have been observed at the Arctic regions too recently. This is a dangerous trend, because unlike the Southern Polar hemisphere, the Northern Polar hemisphere is well populated.

Ozone hole is caused by chemicals called CFCs, or chlorofluorocarbons. CFCs escape into the atmosphere from refrigeration and propellant devices and processes. In the lower atmosphere, they are so stable that they persist for decades. Eventually, some of the CFCs reach the stratosphere where chemical reactions take place primarily on the surface of polar stratospheric clouds, ice particles, or liquid droplets, which form at high altitudes in the extreme cold of the polar regions. Ultraviolet light breaks the bond holding chlorine atoms (Cl) to the CFC molecule. Chlorine then destroys ozone molecules by “stealing” their oxygen atoms. The breakdown of ozone in the stratosphere makes it unable to absorb ultraviolet radiation. Consequently, the unabsorbed ultraviolet-B radiation is able to reach the Earth’s surface. The extent of ozone destruction is extremely sensitive to small changes in stratospheric temperature.

Another culprit responsible for the ozone depletion is nitrous oxide (N2O). The major sources of nitrous oxide are industrial processes and combustion engines of various vehicles. They are also emitted from livestock manure and sewage. Like CFCs, Nitrous oxide  is stable when emitted at ground level, but breaks down when it reaches the stratosphere to form nitrogen oxides that trigger ozone-destroying reactions.

In 1987 several UN countries gathered at Montreal, Canada, and signed a treaty to protect the stratospheric ozone layer. The Montreal Protocol stipulated that the production and consumption of compounds that deplete ozone in the stratosphere—chlorofluorocarbons, halons, carbon tetrachloride, and methyl chloroform—are to be phased out by 2005.

Chemical manufacturers soon created substitutes for CFCs with little added costs; thus, our life styles remained greatly unaffected by the switch-over from CFC’s. This has had the effect of putting a slow stopper on the Ozone hole.

Now, the issue of a possible connection between ozone hole and global warming is a controversial subject even among scientists. In fact, there is no unanimity in either of the assertions that Antarctica is warming or cooling. The British Antarctic Survey says categorically Antarctica to be both warming around the edges and cooling at the center at the same time. Thus it is not possible to say whether it is warming or cooling overall. Because there are too many parameters governing the global temperatures, it is difficult to correlate the theoretical temperature rise at the Antarctic caused by a thinner ozone layer with global climatic changes. It is useful to remember here that Ozone itself is a greenhouse gas and its thinning over the region reduces heat trapped over it and helps create sea spray that forms reflective, cooling clouds.

Source: http://scienceray.com