Ozone hole trend

[Bugalugs]

I am having difficulty assessing the overall trend in ozone hole size. On the one hand the hole was predicted to get smaller, on the other hand it was record large in 2015.

Online graphics that I have was hoping to compare with recent figures tend to cut off around 2014.

Is there a good page out there assessing the trend? Or a recent animated graphic incorporating the past 30 years or so up to now?

[kassy]

Maybe this helps?

https://ozonewatch.gsfc.nasa.gov/

https://ozonewatch.gsfc.nasa.gov/statistics/annual_data.html

[gerontocrat]

I am having difficulty assessing the overall trend in ozone hole size. On the one hand the hole was predicted to get smaller, on the other hand it was record large in 2015.

Online graphics that I have was hoping to compare with recent figures tend to cut off around 2014.

Is there a good page out there assessing the trend? Or a recent animated graphic incorporating the past 30 years or so up to now?

https://ozonewatch.gsfc.nasa.gov/ has it all?

[Bugalugs]

Crikey, don't know how I missed that, I'll buy a white cane.

[Tom_Mazanec]

In the 1980s, the World Acted to Save the Ozone Layer. Here's Why the Fight Against Climate Change Is Different
https://time.com/5681661/climate-change-ozone-history/

The discovery of the ozone hole was sometimes called a “focusing event” — an event that focuses public attention on a particular problem. The effects of climate change are beginning to be more and more perceptible to different people, but they are not yet as obvious as the ozone hole. It might have to be that a big piece of Greenland falls into the sea and sea levels rise by a foot — that would get us thinking about climate change. But the slow nature of climate change doesn’t lend itself to that kind of shock value.

This particular summit just doesn’t seem like any kind of analogy to the ozone issue. We [in the U.S.] actually were the leaders on ozone depletion and on smog, and frankly, we’re doing so badly right now on environmental issues. We’re not going to be the leaders. We’re not going to go into this summit and say anything that will help to create an international agreement.

[kassy]

What fresh hell?

Ozone layer: Concern grows over threat from replacement chemicals

Substances used for air conditioning in almost all new cars are building up in the environment and may pose a threat to human health, researchers say.

These "ozone friendly" chemicals have been introduced to replace products that were damaging the ozone layer.

Now widely used across industry, these alternatives do not break down in the environment.

Scientists have now found increasing levels of these chemicals in Arctic ice samples dating back to the 1990s.

...

However, there are now concerns that the solution may be inadvertently damaging the environment and threatening human health.

Canadian researchers, studying ice samples from the Arctic dating back to the 1990s, have found "dramatically" increasing levels of ozone replacements called short chain perfluoroalkyl carboxylic acids (scPFCAs).

"We're seeing much, much larger levels, on the order of 10 times higher now than we saw before the Montreal Protocol," said Prof Cora Young, from York University in Toronto, the study's corresponding author.

"We don't know a lot about them and their potential toxicity, but we do know that we are committing the environment to a great deal of contamination."

The compounds being detected in the Arctic are in the same class as perfluoroalkyl substances, or PFAS, sometimes called the "forever chemicals".

These long-lasting chemicals are found in everything, from furniture to clothing to food wrapping to drinking water.

There is growing concern about the role of PFAS in serious health conditions including cancer, liver damage and decreased fertility.

The related products, found in the Arctic ice samples, do not break down in the environment and current water filtration technology is unable to remove them.

The scientists expect levels of scPFCAS to increase markedly in the future.

Car trouble ahead?

As part of the efforts to replace CFCs, car manufacturers around the world agreed to use a different coolant in air conditioning called HFC-134a which was introduced in 1992.

While HFC-134a was less damaging to the ozone layer, it was unfortunately a very powerful greenhouse gas, around 1,400 times more warming that CO2.

So manufacturers in the US and Europe agreed to phase out HFC-134a and by 2017 all new cars had to use a different coolant for air conditioning called HFO-1234yf.

While this chemical doesn't damage ozone, and is not a greenhouse gas, it does unfortunately break down to produce short chain PFCAs.

"It has a very low global warming potential, but has a much higher propensity to form these persistent products," said Prof Young.

https://www.bbc.com/news/science-environment-52663694

Producing Ourselves to Death. 

[kassy]

Smoke from Australia wildfires destroyed healing ozone layer

The damage could become worse if major fires become more frequent with a changing climate

Smoke from major wildfires destroys the ozone layer, a study has warned.

The ozone layer is a protective shield in the Earth’s stratosphere which absorbs most of the ultraviolet radiation reaching us from the sun. Without the ozone layer it would be nearly impossible for anything to survive on the planet.

Atmospheric chemists from the University of Waterloo in Ontario, Canada, found that smoke from the Australian wildfires of 2019 and 2020 destroyed atmospheric ozone in the Southern Hemisphere for months. The ozone shield is a part of the stratosphere layer of the Earth’s atmosphere that absorbs UV rays from the sun.

They also warn that the damage could become worse if major fires become more frequent with climate change.

...

“The Australian fires injected acidic smoke particles into the stratosphere, disrupting the chlorine, hydrogen and nitrogen chemistry that regulate ozone,” said Peter Bernath, research professor in Waterloo’s Department of Chemistry and lead author of the study.

“This is the first large measurement of the smoke, which shows it converting these ozone-regulating compounds into more reactive compounds that destroy ozone.”

In the past, human use of substances – chlorofluorocarbons (CFCs) – caused such life-threatening damage to the ozone layer that in 1987, an international treaty called the “Montreal Protocol” was adopted to ban them.

Similar to the holes over polar regions, the smoke damage is a temporary effect, and the ozone levels returned to pre-wildfire levels once the smoke disappeared from the stratosphere. But an increase in the prevalence of wildfires would mean the destruction happens more often.

...

https://www.independent.co.uk/climate-change/news/wildfires-destroy-ozone-layer-scientists-warn-b2038231.html

[kassy]

Global total ozone recovery trends attributed to ozone-depleting substance (ODS) changes derived from five merged ozone datasets

Abstract
We report on updated trends using different merged zonal mean total ozone datasets from satellite and ground-based observations for the period from 1979 to 2020. This work is an update of the trends reported in Weber et al. (2018) using the same datasets up to 2016. Merged datasets used in this study include NASA MOD v8.7 and NOAA Cohesive Data (COH) v8.6, both based on data from the series of Solar Backscatter Ultraviolet (SBUV), SBUV-2, and Ozone Mapping and Profiler Suite (OMPS) satellite instruments (1978–present), as well as the Global Ozone Monitoring Experiment (GOME)-type Total Ozone – Essential Climate Variable (GTO-ECV) and GOME-SCIAMACHY-GOME-2 (GSG) merged datasets (both 1995–present), mainly comprising satellite data from GOME, SCIAMACHY, OMI, GOME-2A, GOME-2B, and TROPOMI. The fifth dataset consists of the annual mean zonal mean data from ground-based measurements collected at the World Ozone and Ultraviolet Radiation Data Centre (WOUDC).

Trends were determined by applying a multiple linear regression (MLR) to annual mean zonal mean data. The addition of 4 more years consolidated the fact that total ozone is indeed slowly recovering in both hemispheres as a result of phasing out ozone-depleting substances (ODSs) as mandated by the Montreal Protocol. The near-global (60∘ S–60∘ N) ODS-related ozone trend of the median of all datasets after 1995 was 0.4 ± 0.2 (2σ) %/decade, which is roughly a third of the decreasing rate of 1.5 ± 0.6 %/decade from 1978 until 1995. The ratio of decline and increase is nearly identical to that of the EESC (equivalent effective stratospheric chlorine or stratospheric halogen) change rates before and after 1995, confirming the success of the Montreal Protocol. The observed total ozone time series are also in very good agreement with the median of 17 chemistry climate models from CCMI-1 (Chemistry-Climate Model Initiative Phase 1) with current ODS and GHG (greenhouse gas) scenarios (REF-C2 scenario).

The positive ODS-related trends in the Northern Hemisphere (NH) after 1995 are only obtained with a sufficient number of terms in the MLR accounting properly for dynamical ozone changes (Brewer–Dobson circulation, Arctic Oscillation (AO), and Antarctic Oscillation (AAO)). A standard MLR (limited to solar, Quasi-Biennial Oscillation (QBO), volcanic, and El Niño–Southern Oscillation (ENSO)) leads to zero trends, showing that the small positive ODS-related trends have been balanced by negative trend contributions from atmospheric dynamics, resulting in nearly constant total ozone levels since 2000.

How to cite.
Weber, M., Arosio, C., Coldewey-Egbers, M., Fioletov, V. E., Frith, S. M., Wild, J. D., Tourpali, K., Burrows, J. P., and Loyola, D.: Global total ozone recovery trends attributed to ozone-depleting substance (ODS) changes derived from five merged ozone datasets, Atmos. Chem. Phys., 22, 6843–6859, https://doi.org/10.5194/acp-22-6843-2022, 2022.

https://acp.copernicus.org/articles/22/6843/2022/

[kassy]

For completeness:

Ozone depletion over North Pole produces weather anomalies


Many people are familiar with the hole in the ozone layer over Antarctica, but what is less well known is that occasionally, the protective ozone in the stratosphere over the Arctic is destroyed as well, thinning the ozone layer there. This last happened in the spring months of 2020, and before that, in the spring of 2011.

Each time the ozone layer has been thinned out, climate researchers subsequently observed weather anomalies across the entire northern hemisphere. In central and northern Europe, Russia and especially in Siberia, those spring seasons were exceptionally warm and dry. In other areas, such as polar regions, however, wet conditions prevailed. These weather anomalies were particularly pronounced in 2020. Switzerland was also unusually warm and dry that spring.

Whether there is a causal relationship between stratospheric ozone destruction and the observed weather anomalies is a matter of debate in climate research. The polar vortex in the stratosphere, which forms in winter and decays in spring, also plays a role. Scientists who have studied the phenomenon so far have arrived at contradictory results and different conclusions.

New findings are now shedding light on the situation, thanks to doctoral student Marina Friedel and Swiss National Science Foundation Ambizione Fellow Gabriel Chiodo. Both are members of the group headed by Thomas Peter, Professor of Atmospheric Chemistry at ETH Zurich, and are collaborating with Princeton University and other institutions.

Simulations reveal correlation

To uncover a possible causal relationship, the researchers ran simulations that integrated ozone depletion into two different climate models. Most climate models consider only physical factors, not variations in stratospheric ozone levels, in part because this would require much more computing power.

But the new calculations make it clear: the cause of the weather anomalies observed in the northern hemisphere in 2011 and 2020 is mostly ozone depletion over the Arctic. The simulations the researchers ran with the two models largely coincided with observational data from those two years, as well as eight other such events that were used for comparison purposes. However, when the scientists "turned off" ozone destruction in the models, they could not reproduce those results.

"What surprised us most from a scientific point of view is that, even though the models we were using for the simulation are utterly different, they produced similar results," says co-author Gabriel Chiodo, SNSF Ambizione Fellow at the Institute for Atmospheric and Climate Science.

The mechanism explained

The phenomenon as the researchers have now studied it begins with ozone depletion in the stratosphere. For ozone to be broken down there, temperatures in the Arctic must be very low. "Ozone destruction occurs only when it is cold enough and the polar vortex is strong in the stratosphere, about 30 to 50 kilometres above the ground," Friedel points out.

Normally, ozone absorbs UV radiation emitted by the sun, thereby warming the stratosphere and helping to break down the polar vortex in spring. But if there is less ozone, the stratosphere cools and the vortex becomes stronger. "A strong polar vortex then produces the effects observed at the Earth's surface," Chiodo says. Ozone thus plays a major role in temperature and circulation changes around the North Pole.

Greater accuracy possible for long-term forecasts

The new findings could help climate researchers make more accurate seasonal weather and climate forecasts in future. This allows for better prediction of heat and temperature changes, "which is important for agriculture," Chiodo says.

Friedel adds, "It will be interesting to observe and model the future evolution of the ozone layer." This is because ozone depletion continues, even though ozone-depleting substances such as chlorofluorocarbons (CFCs) have been banned since 1989. CFCs are very long-lived and linger in the atmosphere for 50 to 100 years; their potential to cause ozone destruction lasts for decades after they have been taken out of circulation. "Yet CFC concentrations are steadily declining, and this raises the question of how quickly the ozone layer is recovering and how this will affect the climate system," she says.

https://www.sciencedaily.com/releases/2022/07/220707141840.htm

[kassy]

Discovery reveals large, year-round ozone hole over tropics

'New' ozone hole much larger than Antarctic ozone hole

An ozone hole, seven times larger than the Antarctic ozone hole, is currently sitting over tropical regions and has been since the 1980s, according to a Canadian researcher.

In AIP Advances, by AIP Publishing, Qing-Bin Lu, a scientist from the University of Waterloo in Ontario, Canada, reveals a large, all-season ozone hole -- defined as an area of ozone loss larger than 25% compared with the undisturbed atmosphere -- in the lower stratosphere over the tropics comparable in depth to that of the well-known springtime Antarctic hole, but its area is roughly seven times greater.

"The tropics constitute half the planet's surface area and are home to about half the world's population," said Lu. "The existence of the tropical ozone hole may cause a great global concern.

"The depletion of the ozone layer can lead to increased ground-level UV radiation, which can increase risk of skin cancer and cataracts in humans, as well as weaken human immune systems, decrease agricultural productivity, and negatively affect sensitive aquatic organisms and ecosystems."

Lu's observation of the ozone hole comes as a surprise to his peers in the scientific community, since it was not predicted by conventional photochemical models. His observed data agree well with the cosmic-ray-driven electron reaction (CRE) model and strongly indicate the identical physical mechanism working for both Antarctic and tropical ozone holes.

As with the polar ozone hole, approximately 80% of the normal ozone value is found to be depleted at the center of the tropical ozone hole. Preliminary reports show ozone depletion levels over equatorial regions are already endangering large populations and the associated UV radiation reaching these regions is far greater than expected.

In the mid-1970s, atmospheric research suggested the ozone layer, which absorbs most of the sun's ultraviolet radiation, might be depleted because of industrial chemicals, primarily chlorofluorocarbons (CFCs). The 1985 discovery of the Antarctic ozone hole confirmed CFC-caused ozone depletion. Although bans on such chemicals have helped slow ozone depletion, evidence suggests ozone depletion persisted.

Lu said the tropical and polar ozone holes play a major role in cooling and regulating stratospheric temperatures, mirroring the formation of three "temperature holes" in the global stratosphere. He said this finding may prove crucial to better understanding global climate change.

Lu's discovery builds on previous studies of the CRE-initiated ozone-depleting mechanism that he and his colleagues originally proposed about two decades ago.

"The present discovery calls for further careful studies of ozone depletion, UV radiation change, increased cancer risks, and other negative effects on health and ecosystems in the tropical regions," said Lu.

https://www.sciencedaily.com/releases/2022/07/220705112242.htm

Paper (link is usually included with science daily so i usually omit it).
https://aip.scitation.org/doi/10.1063/5.0094629

[kassy]

Some criticism levelled at this research:

A new definition for 'ozone hole'?
Ozone — a gas made up of three oxygen atoms bound together — forms in Earth's upper atmosphere. Most ozone sits in the stratosphere, the atmospheric layer that lies 6 to 31 miles (10 to 50 kilometers) above the planet's surface. There, the gas acts as a kind of sunscreen, shielding Earth from the sun's powerful ultraviolet (UV) rays.

In the 1980s, scientists found that long-lived atmospheric pollutants called chlorofluorocarbons (CFCs) break down into chlorine and bromine when exposed to UV rays beyond the ozone layer, according to NASA's Earth Observatory(opens in new tab). These reactive elements tear O3 molecules apart and thus thin out regions of the ozone layer, creating "holes," primarily over Antarctica, where the frigid atmospheric conditions allow ozone-shredding reactions to unfold very efficiently.

Conventionally, an ozone hole is defined as a region where the ozone concentration dips below 220 "Dobson Units" — a measure of the number of ozone molecules in a given column of air that stretches from the planet's surface to space. The discovery of ozone holes prompted the passage of the 1987 Montreal Protocol, an international treaty aimed at phasing out the production of ozone-depleting chemicals such as CFCs, and now, the ozone layer is on the road to recovery, according to the World Meteorological Organization(opens in new tab) (WMO).

However, in Lu's new study, he warned that a newfound ozone hole may be threatening the lives of billions of people living in the tropics.

Specifically, Lu reported discovering a "large and all-season ozone hole" in the lower stratosphere over the tropics, 6.2 to 15.5 miles (10-25 km) above Earth's surface. This hole is similar in "depth" to the seasonal ozone hole that opens up over Antarctica in late winter and early spring, but covers an area seven times larger than that of the springtime Antarctic hole, he reported.

...

Rather than using the conventional definition of an ozone hole, Lu defined a hole as "an area of O3 loss larger than 25% compared with the undisturbed atmosphere." Ozone holes observed over the North Pole were marked by a roughly 25% drop in ozone, so this new definition is justified, he told Live Science. It's key to note that "no ozone hole over the tropics would be observed by the conventional definition of an ozone hole," because the total ozone levels over the tropics fall above the 220 Dobson Unit threshold, Lu noted in his report.

...

"There is no 'tropical ozone hole,'" said Paul Young, an atmospheric scientist at Lancaster University in England and co-lead author of the 2022 Scientific Assessment of Ozone Depletion, a report prepared by the WMO and the United Nations.

"The author’s identification of a 'tropical ozone hole' is down to him looking at percentage changes in ozone, rather than absolute changes, with the latter being much more relevant for damaging UV reaching the surface," Young said. "Interestingly, his article also does not draw from the vast literature that explores and documents ozone trends in all regions of the atmosphere."

One huge factor that influences ozone concentrations in the tropical stratosphere is a phenomenon called the Brewer-Dobson circulation, a global pattern of air circulation that pushes ozone out of the tropics and toward the poles, said Marta Ábalos Álvarez, a researcher in the Department of Earth Physics and Astrophysics at the Complutense University of Madrid. This circulation has sped up in recent years(opens in new tab) due to climate change, and this acceleration explains the long-term patterns of ozone depletion observed in the tropics, she said.

...

https://www.space.com/new-hole-in-ozone-layer-debunked

For the curious:

Observed changes in Brewer–Dobson circulation for 1980–2018
https://iopscience.iop.org/article/10.1088/1748-9326/ab4de7

[vox_mundi]

Water In Atmosphere from Tonga Eruption May Weaken Ozone Layer
https://phys.org/news/2022-08-atmosphere-tonga-eruption-weaken-ozone.html



A team of researchers at the California Institute of Technology's Jet Propulsion Laboratory, working with a colleague from the University of Edinburgh, has found evidence suggesting that the Hunga Tonga-Hunga Ha'apai eruption earlier this year may have pushed so much water into the atmosphere that there is a possibility it could weaken the Earth's ozone layer. In their paper published in the journal Geophysical Research Letters, the group studied data from satellites to measure how much water was launched into the atmosphere and believe it could lead to weakening of the ozone layer.

The Tonga eruption occurred January 15, on and below the seabed in the Pacific Ocean near Tonga. In addition to spewing a variety of gases into the ocean, some of which eventually made their way into the atmosphere, the blast also blew massive amounts of ocean water skyward—high enough that a lot of it made it into the stratosphere. Water at such heights, the researchers note, could be there for many years—perhaps decades.

In addition to dramatic video imagery, the researchers also found measurements of released sulfur dioxide. Comparing it with other eruptions, they found the amount was not unusual. It was when they checked how much water was blown into the atmosphere that they found something surprising: It was a larger amount than had ever been recorded before, and it was blown higher than ever observed before—some of it into the mesosphere. Their calculations showed that the total amount of water that made its way into the stratosphere was approximately 146 Tg. Put another way, they suggest that seawater from the eruption increased the total amount of water in the stratosphere by approximately 10%.

The researchers note that while the sulfur ejected into the atmosphere could have a small cooling effect on the planet, the water will have a warming effect because water absorbs energy from the sun. They also note that when water molecules mix with oxygen atoms, hydroxide is produced, which could lead to reductions in ozone.

L. Millán et al, The Hunga Tonga‐Hunga Ha'apai Hydration of the Stratosphere, Geophysical Research Letters (2022).
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GL099381

Key Points:

... Following the Hunga Tonga-Hunga Ha'apai eruption, the Aura Microwave Limb Sounder measured enhancements of stratospheric H2O, SO2, and HCl

The mass of SO2 and HCl injected is comparable to that from prior eruptions, whereas the magnitude of the H2O injection is unprecedented

Excess stratospheric H2O will persist for years, could affect stratospheric chemistry and dynamics, and may lead to surface warming

[kassy]

Europe urged to clamp down on growing greenhouse gases black market

Illegal hydrofluorocarbons smuggled into the EU amount to nearly 30% of the legal trade, according to the Environmental Investigation Agency

The London-based Environmental Investigation Agency (EIA) has urged the European Public Prosecutor’s Office to launch an investigation into the illegal multi-million euro trade in climate-damaging hydrofluorocarbons (HFCs) in Europe.

HFCs are industrial refrigerant gases used in, among other things, air-conditioning and supermarket cooling units.

As part of a gradual phase down in using HFCs, the EU has introduced a quota system through its F-Gas Regulation to limit the volume of these greenhouse gases on the market.

The measure cut the supply by 37% in 2018 which in turn caused prices to soar while fuelled a black market across Europe.

The EIA said Romania has become a major gateway for HFC smuggling.

In its recent report, the EIA states that smugglers exploited loopholes in the F-Gas Regulation and customs procedures, paid off corrupt officials and benefited from lax border controls.

The EIA’s investigation, which compared data reported under the EU F-Gas Regulation with trade data, estimated that the volume of illegal HFCs smuggled into the EU amounted to between 20% and 30% of the legal trade.

EIA Senior Climate Campaigner Fionnuala Walravens said: “Despite giving Romanian law enforcement our evidence 12 months ago, no action appears to have taken place.

“The illegal trade not only jeopardises the achievement of the EU’s climate objectives, but it has also resulted in the loss of approximately €77 million (£64.3m) a year in VAT and customs duties.”

https://www.energylivenews.com/2022/08/03/europe-urged-to-clamp-down-on-growing-greenhouse-gases-black-market/

[morganism]

 International collaboration uses auroras to reveal a new factor that damages the ozone layer

Along with solar radiation from the Sun, cosmic rays and high-energy plasma particles, such as ions and electrons, bombard the Earth's atmosphere. Among these particles, electrons in the radiation belt, the layer that surrounds the Earth in space, may fall along magnetic field lines into the Earth's atmosphere. When they fall, their charge ionizes the atmosphere and produces nitrogen oxides and hydrogen oxides. Both compounds contribute to ozone loss.

Although high-energy plasma particles damage the ozone layer, details of their impact are less well understood. This is because such particles are not visually observable, making it difficult to ascertain their location. However, when these charged particles interact with the upper atmosphere, they emit an isolated proton aurora that falls toward Earth. Normally, auroras appear as a belt around the north and south poles, however, these isolated proton auroras are visible as isolated spots or bands at lower latitudes.

 To detect electrons over the aurora, the team used a combination of satellite remote sensing, ground-based electromagnetic wave observations, and information from the International Space Station. For the first time, the data revealed the formation of a localized ozone hole in the middle atmosphere, about 400 km wide, which was associated with isolated proton auroras.

Comparing their results to simulations, the researchers found that the damage was much greater than predicted. Up to 10-60% of the ozone directly below the aurora was destroyed 90 minutes after it began.


 "This is the first observational study in the world to show that radiation belt electron fallout from space around the Earth has a direct, immediate, and localized effect on atmospheric changes in the mesosphere," the researchers said. "

This study revealed that radiation belt electrons falling into the atmosphere from space around the Earth have a rapid and localized effect on the composition of the micro-atmosphere, including ozone. This finding is expected to contribute to an improved prediction of changes in the Earth's atmospheric environment by considering the effects of atmospheric ionization by high-energy plasma from space."

https://forum.arctic-sea-ice.net/index.php/topic,2795.msg342345.html#msg342345



Localized mesospheric ozone destruction corresponding to isolated proton aurora coming from Earth’s radiation belt

Relativistic electron precipitation (REP) from the Earth’s radiation belt plays an important role in mesospheric ozone loss as a connection between space weather and the climate system. However, the rapid (tens of minutes) destruction of mesospheric ozone directly caused by REP has remained poorly understood due to the difficulty of recognizing its location and duration. Here we show a compelling rapid correspondence between localized REP and ozone destruction during a specific auroral phenomenon, the called an isolated proton aurora (IPA). The IPA from the Earth’s radiation belt becomes an important spatial and temporal proxy of REP, distinct from other auroral phenomena, and allowing visualizing micro-ozone holes. We found ozone destruction of as much as 10–60% within 1.5 h of the initiation of IPA. Electromagnetic ion cyclotron waves in the oxygen ion band observed as the driver of REP likely affect through resonance with mainly ultra-relativistic (> 2 mega-electron-volts) energy electrons. The rapid REP impact demonstrates its crucial role and direct effect on regulating the atmospheric chemical balance."

https://www.nature.com/articles/s41598-022-20548-2?error=cookies_not_supported&code=3518e1ff-b34e-4d0a-9b7c-df3e0d91a63f

[kassy]

Hole in ozone layer ‘larger than usual’


New data has revealed the hole in the ozone layer has taken longer than usual to close and was relatively large this year.

‘Unusual’ data from the European Space Agency’s Copernicus Atmosphere Monitoring Service (CAMS) shows the ozone hole has remained larger than usual throughout November and coming to an end well into December.

The Antarctic ozone hole usually starts opening during the Southern Hemisphere spring (in late September) and begins to decline during October, before typically coming to an end during November. Nonetheless, the CAMS data from the last three years shows different behaviour.

CAMS Director, Vincent-Henri Peuch explains: “There are several factors influencing the extent and duration of the ozone hole each year, particularly the strength of the Polar vortex and the temperatures in the stratosphere.

“The last three years have been marked by strong vortices and low temperatures, which has led to consecutive large and long-lasting ozone hole episodes.

“There is a possible connection with climate change, which tends to cool the stratosphere. It is quite unexpected though to see three unusual ozone holes in a row. It is certainly something to look into further.”

The date of the ozone hole closure in 2020 and 2021 was December 28 and December 23 respectively, and scientists expect that this year’s hole will close within the coming days.

The last three ozone holes have been not only exceptionally persistent but also had a relatively large extension. During these three years, the ozone hole has been above 15 million km2 (similar to the size of Antarctica) during most of November.

However, despite these recent fairly large ozone holes, there are consistent signs of improvement of the ozone layer. Thanks to the implementation of the Montreal Protocol, the concentrations of Ozone Depleting Substances (ODS) have been slowly but steadily declining since the late nineties.

It is expected that in 50 years their concentrations in the stratosphere will have returned to the pre-industrial levels and ozone holes will no longer be experienced regardless of Polar vortex and temperature conditions.

https://www.independent.co.uk/climate-change/news/hole-in-ozone-layer-larger-than-usual-b2246082.html

[kassy]

‘This shouldn’t be happening’: levels of banned CFCs rising

Researchers have detected increased emissions for five ozone-depleting chlorofluorocarbons.

The Montreal Protocol, which banned most uses of ozone-destroying chemicals known as chlorofluorocarbons (CFCs) and called for their global phase-out by 2010, has been a great success story: Earth’s ozone layer is projected to recover by the 2060s.

So atmospheric chemists were surprised to see a troubling signal in recent data. They found that the levels of five CFCs rose rapidly in the atmosphere from 2010 to 2020. Their results are published today in Nature Geoscience1.

“This shouldn’t be happening,” says Martin Vollmer, an atmospheric chemist at the Swiss Federal Laboratories for Materials Science and Technology in Dübendorf who helped to analyse data from an international network of CFC monitors. “We expect the opposite trend, we expect them to slowly go down.”

At current levels, these CFCs do not pose much threat to the ozone layer’s healing, said Luke Western, a chemist at the University of Bristol, UK, at an online press conference on 30 March. CFCs, once used as refrigerants and aerosols, can persist in the atmosphere for hundreds of years. Given that they are potent greenhouse gases, eliminating emissions of these CFCs will also have a positive impact on Earth’s climate. The collective annual warming effect of these five chemicals on the planet is equivalent to the emissions produced by a small country like Switzerland.

It’s highly likely that manufacturing plants are accidently releasing three of the chemicals — CFC-113a, CFC-114a and CFC-115 — while producing replacements for CFCs. When CFCs were phased out, hydrofluorocarbons (HFCs) were brought in as substitutes. But CFCs can crop up as unintended by-products during HFC manufacture. This accidental production is discouraged by the Montreal Protocol, but not prohibited by it.

“A lot of this probably boils down to the factory level,” Vollmer says, pointing out that HFC production is on the rise. “A factory can be run relatively clean or relatively dirty.”

...

https://www.nature.com/articles/d41586-023-00940-2

[trm1958]

Don’t forget to add those five gasses to your tally, Stephan.