1. How Big Was the Antarctic Ozone Hole in 2025?
The ozone hole is an area of reduced ozone above Antarctica. It is not a physical hole in the ground. According to the Japan Meteorological Agency, the hole reached its annual maximum size on September 9, 2025. The area was about 22.8 million square kilometers (about 8.8 million square miles). This is approximately 1.6 times the size of the Antarctic continent [5].
This size is similar to the average over the last 10 years, which is about 23.4 million square kilometers (about 9 million square miles) [5]. However, we cannot simply say it has "shrunk" without looking at different measurements. NASA and NOAA announced that the average area from September 7 to October 13 was about 18.71 million square kilometers (about 7.2 million square miles). This was the 5th smallest since 1992 [6]. It is important to view these numbers separately, as they use different counting methods.
2. Why CFCs Were Created as Safe Coolants
Chlorofluorocarbons, or CFCs, were synthesized in 1928 by Thomas Midgley Jr. in the United States. At that time, coolants used toxic gases like ammonia. CFCs were created as a safe alternative [1].
From the 1930s to the 1960s, CFCs became widely used in refrigerators, air conditioning, and sprays. They were also used in foam plastics. The original goal was safety. No one created them with bad intentions. The key point is that the motivation for introducing them was safety.
3. How Scientists Discovered CFCs Damage the Ozone Layer
In 1974, researchers Rowland and Molina at the University of California showed that CFCs break down in the stratosphere when hit by ultraviolet light. This releases chlorine. They warned that this chlorine could chain-react to destroy ozone [1].
In May 1985, scientists Farman, Gardiner, and Shanklin at a British Antarctic survey station reported to the journal Nature that total ozone above Antarctica in spring (October) had dropped significantly since the late 1970s. This report was based on observations at places like Halley Base [2]. This is considered the discovery of the ozone hole.
In 1995, Molina, Rowland, and Crutzen shared the Nobel Prize in Chemistry for their work on ozone in the atmosphere [10]. Who questioned the gas that was supposed to be safe?
4. The Montreal Protocol: A Global Agreement to Stop CFCs
The Montreal Protocol was adopted in September 1987 and took effect in January 1989. Japan accepted it in 1988. By 2009, including the EU, 196 parties had joined, making it a treaty with universal participation [3][12].
The protocol required the phase-out of specific CFCs by 1996 for developed countries and by 2015 for developing countries. However, deadlines vary by substance and country [3].
In Japan, under the Ozone Layer Protection Act (established in 1988), CFC production ended completely at the end of 1995. HCFC production also ended at the end of 2019 [11]. Note that "ending production" is different from dealing with CFCs already inside existing machines or recovering them.
5. Why the Ozone Layer Recovers So Slowly
CFCs stay in the atmosphere for a long time. The estimated lifetime is about 55 years for CFC-11 and about 140 years for CFC-12 [1]. These are estimates, not exact rules. So, even if we stop emitting them, it takes time for them to disappear from the sky.
NASA states that the amount of ozone-depleting substances in the Antarctic stratosphere has decreased by about one-third since its peak around 2000. The recovery of the ozone hole above Antarctica is expected around the late 2060s [6].
A 2022 assessment by the WMO and UNEP predicts that total ozone will return to 1980 levels around 2066 for Antarctica, 2045 for the Arctic, and 2040 for the whole world (average of 60°N to 60°S). These are all "about" predictions [7].
The Japan Meteorological Agency sees a decreasing trend since around 2000, though the hole is still larger than in the 1980s [5]. The WMO noted that the 2025 hole was relatively small and short-lived, closing about 3 weeks early. This supports the long-term recovery trend, but yearly changes depend on atmospheric movement, so observation must continue [8].
6. HFCs and the Kigali Amendment: Replacing CFCs Without Warming the Planet
Alternative gases called HFCs do not destroy ozone, but they have a strong greenhouse effect. Because their production and consumption increased, a phased reduction was decided in the Kigali Amendment in October 2016. Japan ratified it in December 2018, and the amendment took effect on January 1, 2019 [4]. Reduction deadlines differ for developed and developing countries.
The WMO and UNEP assess that about 99% of regulated ozone-depleting substances have been phased out [9]. If the Kigali Amendment is followed, it is estimated to avoid 0.3 to 0.5°C of temperature rise by 2100. The Montreal Protocol as a whole is estimated to have avoided about 0.5 to 1°C by around 2050 [9]. These two numbers cover different scopes, so they should not be added together.
7. Where to Find Ozone Hole Data Yourself
You can check the Japan Meteorological Agency's page on the "Status of the Ozone Hole" to see maps of the Antarctic ozone hole and graphs of the annual maximum area. You can see how the size fluctuates each year. Checking the unit on the graph (10,000 km²) and comparing it to the size of Antarctica (about 1.6 times) helps make the numbers feel real.
For official information, the Japan Meteorological Agency publishes an annual summary of the Antarctic ozone hole. The Ministry of the Environment's page on the Montreal Protocol summarizes Japan's efforts in Japanese.