Tag Archives: ozone hole

Finally, some good environment news : the 2020 ozone layer hole closed down

In 2020 the Ozone Layer above the Antarctic was big compared to previous years, both in depth and area. Data from the Copernicus Atmospheric Monitoring Service shows the maximum occurred in October with more than 20 million square kilometers.

Every year, humans emit chemicals into the atmosphere, some of which can alter the ozone layer. But the ozone layer is pretty robust. In order for the depletion of ozone to start, temperatures in the stratosphere must be below -78°C so chemicals become active enough to destroy ozone molecules. This doesn’t always happen, but a very stable Antarctic vortex helped keep temperatures below this threshold.

Credits: NOAA

Polar vortexes are low-pressure systems, which form in the upper atmosphere. Whenever the polar Jetstream (a fast-flowing, meandering, narrow wind band) is strong, the vortex is more stable. The counterpart is a wavy polar vortex due to a weaker Jetstream. When the polar vortex is wavy, North America faces a cold winter. Australia, on the other hand, faces a wetter season.

If the polar vortex is both stable and strong, stratospheric clouds get colder, which creates the perfect conditions for the chemical reactions to start depleting the stratospheric ozone. The 2020 season had such a strong vortex. Researchers feared it could keep active for a long time and reach the maximum depletion detected. Luckily, this didn’t turn out to be the case.

It’s not the first time something like this has happened. The image below shows the comparison between previous depletion and the one from 2020. The 2020 hole’s area wasn’t as big as in 2017, but it was very stable and lasted longer. It only really started receding after mid-December.

Ozone Layer area from year to year. Credits: Coperninus ECMWF.

The lowest record of the ozone layer’s hole happened in 2019 . The entire season can be seen in the video bellow from NOAA Ozone Watch. The colors alter from blue/purple, smaller concentrations of ozone, to green/yellow, bigger concentrations.

From year to year, there may be a bigger or smaller hole, but in the end, if we wouldn’t produce the ozone-depleting chemicals, this wouldn’t be a problem in the first place. We still need to reduce emissions, and there’s no real substitute for this.

Making the average ozone hole small enough not to be so harmful is still a challenge, however. We still emit ozone-depleting chemicals, which may not be yet banned. The Montreal Protocol list needs to be continuously changed, policies concerning the environment need to be as developing as the science behind it.

The largest ozone hole over the Arctic ever recorded is now plugged

The polar vortex weakened and split in two has diluted the ozone hole. Credit: Copernicus ECMWF.

This spring season, the ozone layer over the Arctic experienced a tear, which grew into the biggest ozone hole across the North Pole in recorded history. Amid tensions and gruesome daily news about the COVID-19 pandemic, it seemed like the apocalypse was nigh. Good news, though: the ozone hole was plugged nearly as fast as it appeared thanks to natural atmospheric activity.

Since it was first spotted in February, the hole in the Arctic ozone layer stretched over 620,000 square miles (1,600,000 square kilometers). No sizable hole that comes near this caliber has been reported in the Arctic since 2011.

Now, the hole has been plugged.

Researchers affiliated with the Copernicus Program, the European Union’s Earth observation program, have been on top of the situation since the ozone hole was first signaled.

This week, they announced that the “rather unusual” hole over the Arctic was not related at all to human activity and was instead caused by a strong Arctic polar vortex.

As such, the ozone layer recovery cannot be pegged to massive reductions in pollution to the coronavirus-related nationwide lockdowns.

Polar vortexes, the kind that triggered this recent massive gaping hole in the ozone layer 11 miles above the Arctic surface, are essentially large areas of low pressure and cold air that surround both of the planet’s poles.

These atmospheric phenomena wean over the summer and strengthen in the winter. Typically, polar vortexes are much weaker over the Arctic compared to the Antarctic due to local topography, as nearby land and mountain ranges disturb the flow of air more.

Ozone hole in Antarctica is a different matter entirely

At ground level, ozone or smog is a poisonous chemical often expelled by vehicle exhaust. Higher up in the stratosphere, ozone accumulates at altitudes between 10 and 50 km where it acts as a shield against the harmful ultraviolet rays, which can cause cancer. Ozone holes occur naturally from cooling, but man-made chemicals greatly accelerate their formation.

While ozone depletion over the Arctic in natural, the same can’t be said about the one in the stratosphere above Antarctica.

Almost four decades ago, scientists had learned that chlorine-containing industrial chemicals triggered the formation of a gaping hole in the ozone layer right above the icy continent.

Since then, the ozone layer has recovered after a UN emergency panel banned the use of chlorofluorocarbons (CFCs) under the Montreal Protocol. This was one of the few highly commendable episodes where nearly all the world’s countries chose to set aside their differences and work for the common good of the planet and all life that calls it home.

Currently, the ozone hole above Antarctica is the size of North America, which sounds humongous. However, it’s the smallest it’s been since 1988, according to NASA.

Ozone Hole.

Ozone hole at its slimmest after 30 years of international effort, keeps shrinking

The hole in our planet’s ozone layer is getting patched up. At its peak this year, the hole grew to be two and a half times the size of the US territory, its smallest proportions since 1988 according to NASA.

Ozone Hole.

It’s blue, it’s menacing, it’s a bit tinier than last year! Hurrah for progress!
Image via NASA / Ozone Hole Watch.

Spreading up to 7,6 million square miles (19.69 million km2) at its peak this year on September 11, the hole in our atmosphere’s ozone layer seems to be healing. The hole, currently looming above Antarctica, was 1.3 million square miles (3.36 million km2) smaller than last year, the smallest it’s ever been since 1988, and it keeps shrinking.

Atmospheric sunscreen

Ozone, sometimes called trioxygen, is an allotrope (a particular structural layout) of oxygen. It’s a molecule made up of three oxygen atoms, O3, and is less chemically stable than the regular O2 molecule. Ozone is a pale-blue, toxic and quite smelly gas, but that’s ok since it breaks down into regular oxygen in the lower atmosphere. It’s also a relatively rare gas, generally formed in the upper atmosphere under the action of UV rays and the charges they generate in the lower layers of the stratosphere.

Because chemistry has a sense of humor, that same ozone layer absorbs virtually all (98% to 99%) of incoming, medium-frequency UV radiation. Awesome news if you like being alive or at least not in constant agony from radiation burns, since UV radiation can wreak havoc on organisms living on land. Exposure to higher levels of UV radiation (such as those associated with a thinned ozone layer) significantly raise the risks of developing cataract and skin cancer. Wide-scale exposure to UV levels expected in the absence of the ozone layer would drastically impact whole ecosystems at a time, and would significantly change the shape of life on Earth as we today know it.

Heavy use of ozone-damaging chemicals — in particular, clorofluorocarbons and hydrochlorofluorocarbons (CHCs and HCHCs) used in old-timey fridges and spray cans — burned a gaping hole in this layer in the 70’s and 80’s. These substances break apart in the upper atmosphere, freeing chlorine and bromine to bind with the ozone. The reactions are quicker over Antarctica (where the hole currently looms) as the frozen polar stratospheric clouds offer surfaces upon which heterogeneous chemical reactions take place.

The hole understandably had everyone quite panicked. But it’s starting to show signs of healing up.

NASA researchers believe that the increasing temperatures we’ve seen in later years helped plug the hole, as warmer bodies of air in the stratosphere help limit the rise of damaging chemicals, such as chlorine and bromine, to the ozone layer.

“The Antarctic ozone hole was exceptionally weak this year,” Paul Newman, chief scientist for Earth Sciences at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, said in a statement. “This is what we would expect to see given the weather conditions in the Antarctic stratosphere.”

This effect, however, is like the jiggling of the gas indicator while your car is running — quite tiny, and quite chaotic. The lion’s share of the progress, the draining of the gas from your car’s tank in our metaphor, can be tracked down to the year 1987 when the evidence of ozone degradation grew so worrying authorities implemented the Montreal Protocol on Substances that Deplete the Ozone Layer. Over time, the protocol grew to be an international agreement which drove massive efforts, all throughout the world, to phase out most ozone-depleting chemicals.

Almost like international agreements on threatening environmental issues are a good thing in the long run and probably shouldn’t be abandoned, right?

Paris agreement.

Hint, hint, wink, wink, America.
Seen in April at the March for Science, Washington DC. Image credits Becker1999 / Wikimedia.

The good news marks the 30th anniversary of the ozone hole’s discovery. NASA further reports that the ozone hole was at its widest in the year 2000, at 11.5 million square miles (29.78 million km2) and will likely need a further 50 years to return to its 1980s size.

Overall, very encouraging news, but one that goes to show the huge inertia Earth’s systems have in relation to change. A lesson we should take to heart as we try to grapple climate change.

NASA reveals new information on ozone hole – no good news in sight

NASA scientists have revealed new data on the ozone hole that forms each year above Antarctica and found that the decrease of chlorine in the atmosphere hasn’t had any significant positive impact. Chlorine is the most dangerous substance for the ozone layer.

Image Credit: NASA/Ozone Hole Watch

Image Credit: NASA/Ozone Hole Watch

20 years ago, the Montreal Protocol was installed. The Montreal Protocol on Substances that Deplete the Ozone Layer is an international treaty designed to protect the ozone layer and reduce or even eliminate the production of substances which cause damage to the ozone layer. However, two new studies show that despite an apparent reduction in the quantity of chlorine and other such substances, two new studies show that signs of recovery are not yet present.

“Ozone holes with smaller areas and a larger total amount of ozone are not necessarily evidence of recovery attributable to the expected chlorine decline,” said Susan Strahan of NASA’s Goddard Space Flight Center in Greenbelt, Md. “That assumption is like trying to understand what’s wrong with your car’s engine without lifting the hood.”

In order to gather this information, they used satellites to peek through the ozone hole. Strahan and Natalya Kramarova, also of NASA Goddard, turned to data from the NASA-NOAA Suomi National Polar-orbiting Partnership satellite and used the satellite’s Ozone Mapper and Profiler Suite’s Limb Profiler to create a map that shows how the amount of ozone varied with altitude throughout the stratosphere during the 2012 season.

The map revealed not only that the hole isn’t shrinking, but that it is much more complex than previously thought.

“Our work shows that the classic metrics based on the total ozone values have limitations – they don’t tell us the whole story,” Kramarova said.

image_2_0

A look inside the 2012 ozone hole with the Ozone Mapper and Profiler Suite shows how the build-up of ozone (parts per million by volume) in the middle stratosphere masks the ozone loss in the lower stratosphere.
Image Credit: NASA

Basically, classic metrics show that the hole has improved since the Montreal protocol. But in reality, weather parameters (winds, most notably) are responsible for the increased ozone and resulting smaller hole. This is what this study has shown: that winds can have a significant impact on the ozone hole and apparent improvements were only apparent weather-caused changes.

The only good thing is that chlorine emissions have been going down; at a pretty slow pace, but they’ve been going down. However, until chlorine levels in the lower stratosphere decline below the early 1990s level (which is something expected to happen anywhere between 2015-2030) temperature and winds will continue to dictate the variable area of the hole in any given year.

“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.”

Dramatic never before seen depletion of ozone layer in the Arctic region

The ozone layer in the arctic regions has suffered unprecedented damage this winter due to cold weather in the upper atmosphere. By the end of March 40% of the ozone in the stratosphere had been destroyed, compared to the previous record of 30%.

The European Space Agency, the UN World Meteorological Organization (WMO) as well as the Alfred Wegener Institute for Polar and Marine Research have all been monitoring the situation in the arctic regions, and all of them have confirmed the dramatic depletion.

According to the WMO, “depletion of the ozone layer … has reached an unprecedented level over the Arctic this spring because of the continuing presence of ozone-depleting substances…”

The European Space Agency also notes that “Envisat satellite has measured record low levels of ozone over the Euro-Atlantic sector of the northern hemisphere during March.”

The ozone layer may be the ultimate protection against harmful radiation, but it is also extremely vulnerable to chemical substances. The dramatic loss is caused by surprisingly strong winds known as the polar vortex, which secluded the atmospheric mass over the North Pole. To put it in blunt terms, things are bad, and they will get worse.

“Our measurements show that at the relevant altitudes about half of the ozone that was present above the Arctic has been destroyed over the past weeks,” Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association (AWI) researcher Markus Rex said in early March. “Since the conditions leading to this unusually rapid ozone depletion continue to prevail, we expect further depletiofn to occur.”