The ozone layer is on the right path to recovery: Here's how the world made it happen

This article was originally published on 2 December 2022, and updated on 13 September 2023.

In the early 1980s, the fashion was for big hairdos held in place by clouds of hairspray.

What few people realized at the time was that maintaining those gravity-defying styles contributed to havoc high up in the stratosphere.

The problem was the aerosol cans that pumped out the vaporized hair lacquer. The sprays were pressurized with gases known as chlorofluorocarbons (CFCs), which were silently tearing a giant hole in the ozone layer above the South Pole. CFCs were also widely used in other appliances, such as air-conditioning units and refrigerators.

But there is good news from scientists at NASA: the hole is getting smaller. As the world celebrates the International Day for the Preservation of the Ozone Layer on 16 September, let’s head out into space for a closer look at what’s happening.

The ozone layer is part of the stratosphere, which lies 10-50 kilometres above the surface of the Earth. As NASA explains: “Ozone is a gas made up of three oxygen atoms.” As you can see in the infographic below, the ozone layer is fairly low down in the atmosphere.

For a simple gas, ozone plays a major role in the functioning of the Earth’s ecosystems. “Ozone protects life on Earth from the sun’s ultraviolet (UV) radiation,” says NASA. “Ozone in the stratosphere absorbs most of the ultraviolet radiation from the sun. Without ozone, the sun’s intense UV radiation would sterilize the Earth’s surface.”

In the final quarter of 2022, scientists from NASA and the US National Oceanic and Atmospheric Administration reported that the hole in the ozone layer is continuing to shrink. The hole lies above Antarctica, and between 7 September and 13 October 2022, it spanned an average area of 23.2 million square kilometres.

This is well below the average in 2006, when the hole's size peaked at 27.5 million square kilometres.

Scientists have confirmed that the shrinking of the ozone hole has continued a positive trend in recent decades.

“Over time, steady progress is being made, and the hole is getting smaller,” says Paul Newman, Chief Scientist for Earth Sciences at NASA’s Goddard Space Flight Center. “We see some wavering as weather changes, and other factors make the numbers wiggle slightly from day to day and week to week. But overall, we see it decreasing through the past two decades.”

The discovery of the ozone layer hole prompted urgent international efforts to reverse the damage. In 1987, countries around the world came together to sign the Montreal Protocol, which formalized the mission to protect and repair the ozone layer by rapidly reducing the volume of ozone-depleting gases being released into the atmosphere. It’s the only UN treaty that all 198 UN member states have ratified.

The chart above shows that CFCs have almost been completely phased out, declining from over 800,000 tonnes in 1989 to 156 tonnes in 2014. The use of other ozone-depleting gases has been reduced significantly, and work is underway to go further. The Kigali Amendment to the Montreal Protocol agreed in 2016, maps the total phase-out of all ozone-depleting gases by 2047, as illustrated below.

If the Montreal Protocol is fully implemented, the ozone layer is projected to recover completely.

In January 2023, an UN-backed scientific panel published its latest assessment report. It confirms that 99% of ozone-depleting gases have been phased out. Projections from the United Nations Environment Programme (UNEP), suggest the Antarctic ozone layer will recover to 1980 levels by around 2066, with recovery in the rest of the world between 2040 and 2045.

UNEP says international action to restore the ozone layer has protected millions of people from cancer: “Without this treaty, ozone depletion would have increased tenfold by 2050 compared to current levels, and resulted in millions of additional cases of melanoma, other cancers and eye cataracts. It has been estimated, for example, that the Montreal Protocol is saving an estimated 2 million people annually by 2030 from skin cancer.”

This huge reduction in the release of ozone-depleting substances is also helping to avoid 0.5°C of global warming by 2100, according to UNEP, making the Montreal Protocol one of the most successful global agreements of all time.