Measurements from satellites this year showed the hole in Earth’s ozone layer that forms over Antarctica each September was the smallest observed since 1988, continuing its shrinking trend over the last 2 decades.
NASA says the ozone hole reached its peak in the middle of September, covering an area a little over twice the size of the United States, a total of 7.6 million square miles. The National Oceanic and Atmospheric Administration (NOAA) ground and balloon based measurements also showed the least amount of ozone depletion above the continent during the peak of the ozone depletion cycle since 1988.
While the ozone hole is showing gradual improvement over time, NASA attributes this sudden shrinking of the hole to natural atmospheric variability, and not a sign of rapid healing. The smaller hole this year has been influenced by an unstable and warmer Antarctic vortex – the stratospheric low pressure system that rotates clockwise in the atmosphere above Antarctica. This helped minimize polar stratospheric cloud formation in the lower stratosphere. The formation and persistence of these clouds are important first steps leading to the chlorine- and bromine-catalyzed reactions that destroy ozone.
The hole in the ozone layer forms in the Southern Hemisphere’s late winter as the returning sun’s rays react with man-made, chemically active forms of chlorine and bromine. It’s these reactions that destroy ozone molecules.
First detected in 1985, the international community quickly responded knowing how important the ozone layer is to the continuation of life on Earth. The Montreal Protocol was signed by nearly every country around the world. This law adds regulations to ozone depleting compounds, which is what likely caused the hole to form in the first place. These compounds called chlorofluorocarbons can be found in refrigerants, which continue to decline worldwide and are rarely used today.
Ozone is a molecule comprised of three oxygen atoms that occurs naturally in small amounts. In the stratosphere, roughly 7 to 25 miles above Earth’s surface, the ozone layer acts like sunscreen, shielding the planet from potentially harmful ultraviolet radiation that can cause skin cancer, cataracts, suppress the immune system, damage plants, and a list of other side effects. Ozone is a crucial piece of Earth’s atmosphere that protects us from the harmful rays of the sun. But ozone is as necessary in the stratosphere as it is unnecessary at ground level. While a useful sunscreen, ozone is actually poisonous when inhaled. While the levels that occur naturally on Earth would never cause instant health related problems, it can cause a host of issues if breathed in over time. This is why ozone alerts get issued in the summer in many major metro areas because ozone can actually be created on the ground by photochemical reactions between the sun, high heat, and pollution from vehicles and other sources. Many of us know this as smog.
While smog may continue to be an issue that plagues mankind, scientists expect the stratospheric ozone hole to continue to be reduced over the next century, and are hopeful it will be completely repaired by 2100.