How the hole in the ozone layer was patched?

The hole in the ozone layer, which has endangered the globe since the 1980s, is closing, according to a study issued by the United Nations on Monday.

The revelation of a large break in the gaseous barrier that safeguards life on Earth from ultraviolet radiation spurred international concern and action.

AFP explores the collaborative efforts of governments, science, and industry to bridge the gap:

1975-1984: the Antarctic crater

Between 1975 and 1984, British geophysicist Joseph Farman utilizes weather balloons to conduct research that indicates a steady and worrying depletion in the stratospheric ozone layer over the Halley Bay scientific station in the Antarctic.

This “hole,” which frequently occurs in the spring in the southern hemisphere, validates the findings of two University of California chemists, Mario Molina and Sherwood Rowland.

In 1974, they argued that the extensive use of chlorofluorocarbons (CFCs) in refrigeration, hairspray, and other aerosols depletes the ozone layer.

For their discovery, the two scientists received the 1995 Nobel Prize in chemistry.

1985: first contact

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

In 1978, the United States outlawed the use of CFCs in aerosols, and in 1986, they ratified the treaty.

1987: landmark protocol

Two years later, the Montreal Protocol, which defines goals for phasing out the manufacture and use of ozone-depleting chemicals, follows the Vienna Accord.

All UN members finally ratify it, making it one of the most successful environmental agreements in history.

CFCs and halon gases (widely used in fire extinguishers) will be decreased by half during the next decade.

Late in 1987, after scientists reveal that the ozone hole over the Antarctic has grown significantly, the main chemical firms agree to investigate less destructive alternatives to CFCs.

1989:  Crater over the Arctic

Early in 1989, an area of the Arctic’s ozone layer is discovered to be decreasing.

The Montreal Protocol is strengthened in 1990 to prohibit the production of CFCs in developed nations by the year 2000. Rich governments also commit to assisting developing states with Protocol compliance costs.

The next year, China ratifies the pact. India joins in 1992.

1995: HCFCs

By the end of 1995, the European Union had totally banned CFCs and begun the eradication of HCFCs, which deplete the ozone layer and are powerful greenhouse gases.

At a conference held in December, developed nations agree to ban HCFCs by 2020.

2006: record deficit

At the end of September 2006, the greatest hole ever detected in the ozone layer above the Antarctic was reported.

In Montreal, in September 2007, a historic agreement is reached to speed up the removal of HCFCs by poor nations by 10 years, to 2030.

2016: gap closing

Scientists from the United States and the United Kingdom say that the Antarctic ozone hole is shrinking the June 2016 edition of Science. They expect a complete recovery by 2050.

2023: recovery within forty years

The United Nations will report on January 9, 2023, that the ozone layer is on track to recover in forty years.

However, the paper warns that controversial geoengineering tactics to tackle global warming might negate this progress.