To monitor the state and recovery of the ozone layer, each year, the final diameter and depth of a ‘hole’ that opens annually in the ozone layer over Antarctica is measured.
For 2024, the hole over the Earth's southern pole was relatively small compared to other years. At almost 8 million square miles (20 million square kilometres), the monthly average ozone-depleted region in the Antarctic this year was nearly three times the size of the U.S.
Monitoring the state and recovery of the ozone layer is a team of scientists at the National Aeronautics and Space Administration (NASA) and the National Oceanic and Atmospheric Administration (NOAA). Annually, they report on the final diameter and depth of a ‘hole’ that starts to open in the ozone layer during August over Antarctica. This year, the hole reached its greatest one-day size on 28 September at 8.5 million square miles (22.4 million square kilometres).
While the area and size of the hole may be cause for alarm, this is not the case. "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 at NOAA’s Global Monitoring Laboratory.
The ozone layer is a region of high ozone concentration in the stratosphere, 15 to 35 kilometres above Earth's surface. The ozone layer is a region of high ozone concentration in the stratosphere, 15 to 35 kilometres above Earth's surface. It acts as an invisible shield and protects all life on Earth from harmful ultraviolet (UV) radiation from the sun. Without this shield, exposure to higher levels of UV radiation would lead to increases in skin cancers in humans, threaten food production and damage ecosystems.
Scientist in the 1970s were therefore alarmed to realise that chlorofluorocarbons, man-made gases being used in abundance in air conditioners, fridges, aerosols and foams, were destroying ozone molecules far more quickly than they being created. In compromising the effectiveness of this fragile UV filter, the exposure to higher levels of UV radiation would lead to increases in skin cancers in humans, impact food production and damage ecosystems.
Worse, by the mid-1980s, the ozone layer had been depleted to such an extent, that a large area of the Antarctic stratosphere was essentially devoid of ozone, creating a ‘hole’ by early October each year.
Luckily, the Montreal Protocol on Substances that Deplete the Ozone Layer was adopted in 1987. This international treaty designed to control the production and consumption of chlorofluorocarbons and other ozone-depleting substances, paved the way for ozone layer recovery.
The 2022 Quadrennial Assessment of the Montreal Protocol’s Scientific Assessment Panel (SAP) indicates that with continuous implementation and broad compliance of this environmental agreement, global ozone levels will return to pre-1980 levels by the mid-2060s.
“The gradual improvement we’ve seen in the past two decades shows that international efforts that curbed ozone-destroying chemicals are working,” said Paul Newman, former co-chair of the SAP and NASA’s leader of the ozone research team and chief scientist for Earth sciences at its Goddard Space Flight Center in Greenbelt, Maryland. “The 2024 Antarctic hole is smaller than ozone holes seen in the early 2000s.”
According to Newman, the improvement this year is due to a combination of continuing declines in chlorofluorocarbons, along with an unexpected infusion of ozone carried by air currents from north of the Antarctic.
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Full 2024 ozone report available here
Latest status of the ozone layer over the Antarctic available at NASA’s ozone watch
Contact: Stephanie Haysmith, Communications & Public Information, Montreal Protocol Ozone Secretariat, stephanie.haysmith@un.org
