Antarctica Ozone Hole Reaches Seventh-Largest Size, Scientists Cite Weather

Antarctica Ozone Hole Reaches Seventh-Largest Size, Scientists Cite Weather

The ozone hole over Antarctica grew to its seventh-largest size in 48 years of monitoring this year. The expansion revived concerns about Earth’s protective shield against harmful solar radiation. However, scientists from NASA and the National Oceanic and Atmospheric Administration said weather conditions largely drove the unusually large hole. They added that the ozone layer remains on track for long-term recovery.

According to measurements released on November 4, the ozone hole covered an average area of around 25 million square kilometres between September 7 and October 13, 2026. At its peak on September 18, it expanded to approximately 27.1 million square kilometres. This size reached nearly 90 percent of the largest ozone hole ever recorded in 2000.

Weather Drove the Expansion

Scientists attributed this year’s large ozone hole to a powerful polar vortex. This band of strong winds circles Antarctica and traps extremely cold air over the continent. These freezing conditions encourage the formation of special clouds high in the atmosphere. In these clouds, chlorine and bromine released by human-made chemicals trigger reactions that destroy ozone.

This year, weather systems that normally weaken the polar vortex stayed unusually weak during August and September. As a result, the vortex remained stronger and covered a larger area. This created favourable conditions for ozone destruction. “The annual ozone hole has been forming later in the season in recent years, which tells us the ozone layer is healing,” said Paul Newman, a senior NASA ozone scientist.

How the Ozone Layer Works

The ozone layer is a region high above Earth that acts like a natural sunscreen. It absorbs much of the Sun’s harmful ultraviolet radiation. Its depletion is primarily caused by chemicals such as chlorofluorocarbons (CFCs). These chemicals were once widely used in refrigerators, air conditioners and aerosol products.

When these chemicals reach the upper atmosphere, sunlight releases chlorine and bromine atoms. These atoms break down ozone molecules. Without enough ozone, more harmful ultraviolet radiation reaches Earth’s surface. Therefore, the risk of skin cancer and cataracts increases. Crops and marine ecosystems also face greater damage.

Recovery Remains on Track

Despite this year’s increase, scientists say international efforts are working. The 1987 Montreal Protocol helped phase out many ozone-destroying chemicals. As a result, chlorine levels in Antarctica’s upper atmosphere have fallen by around a third from their 1980s peak. NOAA estimates that without these restrictions, the 2026 ozone hole could have been another 3.5 million square kilometres larger.

Scientists expect the Antarctic ozone hole to recover by the 2070s. However, older ozone-destroying chemicals will continue to linger in the atmosphere for decades. Therefore, continued monitoring remains essential.