In 2024, the ozone hole over the Antarctic showed a notable reduction in size, ranking as the seventh smallest since monitoring began post-Montreal Protocol.
This improvement is credited to ongoing reductions in CFC emissions and enhanced atmospheric dynamics that transport ozone southward.
Ozone Layer Recovery Progress in 2024
In 2024, the annual hole in the ozone layer over Earth’s southern pole was relatively small compared to previous years. NASA and the National Oceanic and Atmospheric Administration (NOAA) estimate that, if current trends continue, the ozone layer could fully recover by 2066.
This year’s peak ozone depletion season, which lasts from September 7 to October 13, saw the ozone hole rank as the seventh smallest since recovery efforts began in 1992, following the Montreal Protocol—a global agreement to phase out ozone-depleting chemicals.
The ozone-depleted region over Antarctica averaged nearly 20 million square kilometers (8 million square miles) this year, covering an area almost three times the size of the contiguous United States. On September 28, the hole reached its largest single-day extent of 22.4 million square kilometers (8.5 million square miles).
The map above shows the size and shape of the ozone hole over the South Pole on the day of its 2024 maximum extent. Moderate ozone losses (orange) are visible amid areas of more potent ozone losses (red). Scientists describe the ozone “hole” as the area in which ozone concentrations drop below the historical threshold of 220 Dobson units.
What Is a Dobson Unit?
The Dobson Unit (DU) is the standard measurement for ozone concentration in Earth’s atmosphere. It quantifies the total amount of ozone in a column of air from the surface to the edge of space. One Dobson Unit equals a 0.01-millimeter layer of pure ozone at standard temperature and pressure. For example, 300 DU would form a 3-millimeter ozone layer if compressed. Scientists use Dobson Units to observe ozone health globally, providing insight into seasonal thinning and recovery patterns.
Impact of Global Efforts on Ozone Health
The improvement is due to a combination of continuing declines in harmful chlorofluorocarbon (CFC) chemicals, along with an unexpected infusion of ozone carried by air currents from north of the Antarctic, scientists said.
In previous years, NASA and NOAA have reported the ozone hole ranking using a time frame dating back to 1979, when scientists began tracking Antarctic ozone levels with satellite data. Using that longer record, this year’s hole ranked 20th smallest in area across the 45 years of observations.
“The 2024 Antarctic hole is smaller than ozone holes seen in the early 2000s,” said Paul Newman, leader of NASA’s ozone research team and chief scientist for Earth sciences at NASA’s Goddard Space Flight Center. “The gradual improvement we’ve seen in the past two decades shows that international efforts that curbed ozone-destroying chemicals are working.”
This year, the ozone hole over Antarctica reached its annual maximum extent on September 28th, 2024, with an area of 8.5 million square miles (22.4 square million kilometers.) The hole, which is actually a region of depleted ozone, was the 20th smallest since scientists began recording the ozone hole in 1979. The average size of the ozone hole between September and October this year was the 7th-smallest since the Montreal Protocol began to take effect. Credit: NASA’s Goddard Space Flight Center
UV Radiation and Ozone Depletion Concerns
The ozone-rich layer high in the atmosphere acts as a planetary sunscreen that helps shield us from harmful ultraviolet (UV) radiation from the Sun. Areas with depleted ozone allow more UV radiation to reach Earth’s surface, resulting in increased cases of skin cancer and cataracts. Excessive exposure to UV light can also reduce agricultural yields as well as damage aquatic plants and animals in vital ecosystems.
Scientists were alarmed in the 1970s at the prospect that CFCs could eat away at atmospheric ozone. By the mid-1980s, the ozone layer had been depleted so much that a broad swath of the Antarctic stratosphere was essentially devoid of ozone by early October each year. Sources of damaging CFCs included coolants in refrigerators and air conditioners, as well as aerosols in hairspray, antiperspirant, and spray paint. Harmful chemicals were also released in the manufacture of insulating foams and as components of industrial fire suppression systems.
Monitoring and Future Outlook
The Montreal Protocol was signed in 1987 to phase out CFC-based products and processes. Countries worldwide agreed to replace the chemicals with more environmentally friendly alternatives by 2010. The release of CFC compounds has dramatically decreased following the Montreal Protocol. But CFCs already in the air will take many decades to break down. As existing CFC levels gradually decline, ozone in the upper atmosphere will rebound globally, and ozone holes will shrink.
“For 2024, we can see that the ozone hole’s severity is below average compared to other years in the past three decades, but the ozone layer is still far from being fully healed,” said Stephen Montzka, senior scientist of the NOAA Global Monitoring Laboratory.
Researchers rely on a combination of systems to monitor the ozone layer. They include instruments on NASA’s Aura satellite, the NOAA-20 and NOAA-21 satellites, and the Suomi NPP satellite, jointly operated by NASA and NOAA.
NOAA scientists also release instrumented weather balloons from the South Pole Baseline Atmospheric Observatory to observe ozone concentrations directly overhead. The 2024 concentration reached its lowest value of 109 Dobson units on October 5. The lowest value ever recorded over the South Pole was 92 Dobson units in October 2006.
NASA and NOAA satellite observations of ozone concentrations cover the entire ozone hole, which can produce a slightly smaller value for the lowest Dobson unit measurement.
“That is well below the 225 Dobson units that was typical of the ozone cover above the Antarctic in 1979,” said NOAA research chemist Bryan Johnson. “So, there’s still a long way to go before atmospheric ozone is back to the levels before the advent of widespread CFC pollution.”
View the latest status of the ozone layer over the Antarctic with NASA’s Ozone Watch.
NASA Earth Observatory image by Lauren Dauphin, using data courtesy of NASA Ozone Watch and GEOS-5 data from the Global Modeling and Assimilation Office at NASA GSFC.
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22 Comments
Doesn’t this just coincide with the fact that we passed solar maximum and now it’s like going down? Wouldn’t that be a major driver of this
It’s all a load of old baloney. They are all just trying to justify all the tax grabs. Thieving so and so’s.
Exactly. Anyone that believes anything humankind did resulted in a decrease in the hole needs a brain transplant. China emits more carbon than the whole world combined.
Nothing to do with carbon emissions, read the article. Other chemicals are involved. This is not about petroleum, gas prices, or carbon pollution standards at all.
It’s puzzling that they say that the size and area of the ozone hole within the polar vortex is smaller when geographic area has nothing to do with CFCs and chlorine chemistry. The ozone hole is a very temporary and seasonal depletion of ozone and it has always quickly recovered back to its normal average value of ~300 Dobson units…the global average. There is nothing to repair.
If the half life of Freon 11 and 12 in the atmosphere is 50 years and the world started phasing it out in 92, but CFC’s and HFC’s were still used for many years, wouldn’t 2024 be a little soon to claim success? Also, a molecule of 135 molecular weight (CFC’s 11 and 12) does not often get to the upper atmosphere. Ozone hole was most likely Mt. St. Helens eruption, which put millions of tons of chlorine into the upper atmosphere. My somewhat educated opinion.
“In 2024, the ozone hole over the Antarctic showed a NOTABLE reduction in size, …”
Considering that the “notable reduction” is only about 15% lower than the previous 4 years, which are probably statistically equivalent, and it was about twice what it was in 2019, I think that they are being overly generous in their use of the word “notable.” It is difficult to make precise evaluations because NASA doesn’t provide estimates of the uncertainty (probably better known to most as the “margin of error”). Overall, the average size of the ‘ozone hole’ in recent years has been comparable to the 1990s, shortly after the Montreal Protocol was agreed to. 1998, 2002, and 2019 had unusually small ‘ozone holes,’ probably the result of a breakdown in the Antarctic circumpolar vortex because of warm temperatures.
Don’t take my word for it. Take a look at the official NASA website: https://ozonewatch.gsfc.nasa.gov/
Following are the recent ozone ‘hole’ areas:
[1983 7.9]
2018 22.9
2019 9.3 Antarctic Ozone Hole Is the Smallest on Record Since Its Discovery [See 1983 above]
2020 23.5 Ozone Hole Over the Antarctic Is One of the Largest and Deepest in Recent Years
2021 23.3 Substantial Antarctic Ozone Hole in 2021
2022 23.2 Good News: Ozone Hole Continues Shrinking in 2022
2023 23.1 Ozone Hole Swells to 10 Million Square Miles – One of the Biggest on Record
2024 19.6 Earth’s Invisible Shield Rebounds: The Remarkable 2024 Ozone Recovery
To the right are the titles of corresponding SciTechDaily articles.
Do you think that those NASA press release titles accurately portray what the tabular data show?
So it went and came back. What a bummer, eh? Now one might conclude the atmospheric phenomena don’t have human origins and we don’t want that too happen, do we?
The new concern is the amount of Aluminium Oxide ‘soot’ that will be deposited high in the Earth’s atmosphere by the tens and, later, hundreds of thousands of re-entering Low-Earth Orbit (LEO) megaconstellation satellites launched and to be launched by the likes of SpaceX and the Chinese.
This soot will have an unpredicted effect on our climate, will reduce the darkness of the night sky (so will hamper both professional and amateur astronomy around the globe) but, of relevance to this article, will likely trigger a decline in Ozone concentration 10-15 years after the re-entry. The cumulative effect of dumping 50-100 old satellites into our atmosphere every day will persist even after the problem is detected, debated, litigated, judged, appealed, stopped and declined – probably about fifty years!
There needs to be an international solution to the problems that megaconstellations will create for the climate, ozone hole and Astronomy than dumping them into our atmosphere after their 5-7 lifetime. In the meantime, there should be a moratorium on their launch.
Instead of sending satellites down to the atmosphere what would be wrong with boosting them to an escape path and maybe have them end up in the sun?
Cost!
Sun pollution lol
“This soot will have an unpredicted effect on our climate, …”
“Soot” is usually used to refer to ‘carbon black,’ or elemental carbon. The reflective behavior of a substance depends on its ‘complex refractive index,’ which is composed of a real component (common index of refraction) and an imaginary component (as in i, the square-root of -1), commonly called the extinction coefficient. When things like minerals are crushed, those with low extinction coefficients get lighter colored. Things like metals and sulfides tend to have relatively large extinction coefficients and appear to get darker when reduced to fine particles. From research that I have done, oxides generally have very low extinction coefficients. Therefore, I’m going to predict that the aluminum oxide resulting from re-entry will result in a more highly reflective atmosphere, probably resuting in cooling as from sulfate aerosols. It remains to be seen what the contribution to the aerosol load will be from the electronics being burned up.
NO MENTION of Mount Erebus, which for many year pumped 8,000 tonnes of chlorine directly into the atmosphere above Antarctica EVER DAY.
Why is this ?
Good question Peter! One I gave up asking many years ago. Everyone ignores it! Perhaps it is such a constant factor that they consider other factors as the variables that can be “controlled”? However it must be the reason why the hole is over Antarctica in the first place. My grandfather was a car painter in New Zealand in the 1940s 50s and 60s. He always said that the imported paint could not withstand the sun damage but NZ made paint was much better in this regard. He died well before the hole was discovered. 😉
The so-called ‘Ozone Hole’ is the result of photocatalytic destruction of ozone in the presence of the newly arrived sunlight in the Antarctic Spring. Ozone is metastable, with a short half-life, decaying all Winter in the absence of sunlight. However, in the early-Spring, the decomposition is accelerated by halides crystalizing onto the surface of ice crystals that form in the very cold stratosphere and acting as an ozone-destroying catalyst in the presence of sunlight.
The problem is exacerbated by the Antarctic Circumpolar Vortex, which prevents ozone-enriched air from the tropics, arriving by Brewer-Dobson Circulation, to enter the depleted region of the ‘Hole.’ The extremely low aerial coverage of the ‘Hole’ corresponds to warm years where the polar vortex is weak to non-existent. When the sun gets high enough to start warming the atmosphere, the ‘Ozone Hole’ breaks up (every year) because the ozone-enriched air is able to move into the depleted area.
The whole situation is probably exaggerated because in the Winter, when the sun doesn’t come above the horizon, only very weak, scattered UV is present. The resident animals have evolved to cope with the weak UV, even when it isn’t cloudy, . There is a brief time in the Spring, when the sun is low on the horizon, when the UV may be problematic if one looks at it directly. However, it is rare that the sun is actually above the ‘Hole.’ Instead, with the sun low on the horizon, it has a long path-length, increasing scattering and absorption. Additionally, it is subject to passing through the elevated ozone concentrations outside the circumpolar vortex. I have looked for years for studies documenting the surface UV levels. I even went so far as to write a computer model to predict UV, taking into account all the astronomical variables such as sun elevation and Earth’s distance from the sun. Basically, what I found in the literature was scary talk about how reduced ozone COULD result in skin cancers and cataracts. What I found was that, in the early-80s, the UV levels appeared to be increasing slightly in the southern hemisphere Winter; however, by the summertime, when UV was at its maximum, it appeared to plateau, suggesting that the animals living there in the Summer had probably adapted to tolerate the levels, which were much lower than in the tropics. Besides, feathers don’t develop cancer, and humans wear clothes all the time in Antarctic, and if they are smart, they will wear photochromic sunglasses that block UV.
CIESIN formerly had a model on the internet to predict surface UV for many US cities, based on the date and predicted weather. Clouds reduce surface UV. It quietly disappeared several years ago. When I used it, I didn’t see anything particularly alarming other than the obvious such as wearing sun screen and sun glasses in the Summer, especially at high elevations and in the desert SW.
Note: “aerial” should be “areal.”
I do wish we could edit our comments.
From the Journal of Geophysical Research, “Emission rates of …, HCl, and HF from the active volcano Mount Erebus, Antarctica, increased between 1986 and 1991; …, HCl from 6.9 to 13.3 Gg yr−1 and HF from 4.0 to 6.0 Gg yr−1.” [ https://agupubs.onlinelibrary.wiley.com/doi/10.1029/97JB00155 ]
That is considerably larger than what you cited. The combined halide emissions is about 15 gigagrams per year, or about 16 megatons per year, or about 45,000 tons per day. It is not an insignificant contribution since automobile refrigerants per YEAR are about half the 45 Kt/day.
The article here — https://www.sciencedirect.com/science/article/pii/S1352231015304246 — flat claims that Mt. Erebus is responsible for at least some ozone depletion. The numbers in this article differ by a factor of 1,000 from what I cited above. I made a mistake in the conversion of gigagrams. The correct conversion is 16 kilotons, not megatons. That equates to about 45 tons per day of just HCl and HF; however, SO2 is important too, providing a nucleating seed for ice crystals. In any event, the impact is in the literature. It just never gets mentioned in the government press releases that blame it all on humans.
Now Europe, especially Germany, desperate for energy after having shut down their nuclear plants and finding wind and solar unreliable, are planning to put lots of billions into using Hydrogen for energy storage in the next few years.
As hydrogen is extremely volatile and dangerous, and in addition to big unavoidable leaks, security itself is based on letting the hydrogen out into the atmosphere. We can expect huge amounts of free Hydrogen to appear in the near future.
As Ozone is O3 and the presence of Hydrogen will immediately reduce the 03 to 02 (normal Oxygen), combined with Hydrogen being the lightest gas in existence, it seems unavoidable to me that the Hydrogen will rise up and remove the ozone layer.
Are there any mechanism present that will stop this from happening, or will the new “Hydrogen Economy” kill us all?
Individual molecules are so widely spaced in the stratosphere that there is plenty of room for additional molecules. What will happen, albeit slowly, is that the hydrogen will be oxidized and water will be produced.