The ozone layer is on its way to repairing itself. Here’s how the hole got plugged

Important points
  • The ozone layer, which protects life on earth from deadly solar radiation, is on track to recover within decades.
  • Ozone depletion was most pronounced over the Antarctic region.
  • Scientists and environmentalists around the world have long applauded efforts to heal the ozone hole.
The ozone layer, which shields life on Earth from deadly solar radiation, is on track to recover within decades, but controversial geoengineering programs to curb global warming could reverse that progress, a major scientific review warns.
The scientific assessment, conducted every four years, found a recovery is underway, more than 35 years after all countries around the world agreed to stop producing chemicals that deplete the ozone layer in Earth’s atmosphere, which protects the planet from harmful skin radiation and cancer , cataracts and crop damage.
“In the upper stratosphere and in the ozone hole, we’re seeing things getting better,” said Paul Newman, co-chair of the scientific assessment.

Progress is slow, according to the report, presented Monday local time at the American Meteorological Society meeting in Denver.

The global average amount of ozone at 30 km altitude in the atmosphere will not return to pre-1980 depletion levels before about 2040, the report said.
And by 2045, things won’t be back to normal in the Arctic.
Antarctica, where it’s so thin there’s a huge gaping hole in the stratum every year, won’t be fully repaired until 2066.

Here’s a look at how politicians, scientists, and industry have worked together to plug the hole.

1975-84: Hole over Antarctica

Between 1975 and 1984, British geophysicist Joseph Farman conducted research using weather balloons that revealed a gradual and worrying depletion of the stratospheric ozone layer over the Halley Bay Science Base in Antarctica.
This “hole,” which typically occurs during spring in the southern hemisphere, complements the findings of two University of California chemists, Mario Molina and Sherwood Rowland.
They had argued as early as 1974 that chlorofluorocarbons (CFCs), widely used in refrigeration and in hairspray and other aerosols, deplete the ozone layer.

The two researchers received the 1995 Nobel Prize in Chemistry for their research.

1985: First contract

In March 1985, 28 countries signed the Vienna Convention for the Protection of the Ozone Layer, the first international agreement on the subject, requiring members to monitor ozone depletion and its effects on human health and the environment.

The United States, which banned the use of CFCs in aerosols in 1978, ratified the convention in 1986.

1987: Landmark Protocol

The Vienna Agreement paves the way for the landmark Montreal Protocol two years later, which sets targets for phasing out the production and consumption of ozone-depleting substances.
Originally signed by 24 countries and the then European Economic Community (now EU), it was eventually ratified by all UN members, making it one of the most successful environmental agreements of all time.
The aim is to halve the consumption of CFCs and halong gases (widely used in fire extinguishers) over a period of 10 years.

In late 1987, after scientists discovered that the hole over Antarctica had gotten even bigger, the big chemical companies agreed to develop less harmful alternatives to CFCs.

Healing Ozone

In this false-color image from NASA, blue and purple show the hole in Earth’s protective ozone layer over Antarctica on October 5, 2022. Source: AAP / AP/NASA

1989: Craters over the Arctic

In early 1989, depletion was also observed in the ozone layer over the Arctic.
In 1990, the Montreal Protocol is strengthened to phase out CFC production in industrialized countries by the end of 2000. Rich countries also agree to help poorer countries meet the costs of complying with the protocol.

A year later, China joins the agreement. India joins in 1992.

1995: CFCs

By the end of 1995, the European Union had completely banned CFCs and began eliminating substitute gases called HCFCs (hydrochlorofluorocarbons used in refrigeration and air conditioning), which are both ozone-depleting and powerful greenhouse gases.

Developed countries agree to ban HCFCs by 2020 at a conference in December.

2006: record hole

The largest hole in the ozone layer over Antarctica ever observed was recorded at the end of September 2006.

In September 2007, a historic agreement was struck in Montreal to advance the elimination of HCFCs by developing countries by 10 years to 2030.

2016: Closing the gap

In June 2016, US and British researchers wrote in Science magazine that the hole over Antarctica was shrinking. They expect a full cure by 2050.

2023: recovery within four decades

On January 9, 2023, the UN announces that the ozone layer is on track to fully recover within four decades.

But it warns that controversial geoengineering programs to curb global warming could reverse that progress.

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