The ozone layer - a fragile shield of gas that protects the Earth from the harmful rays of the sun - is "on the road to recovery", the said on Thursday in his message for the World Ozone Day.

Crediting the Montreal Protocol, which "began life as a mechanism to protect and heal the ozone layer", Secretary-General Antonio Guterres said that over the course of three decades, "it has done its job well".

The multilateral treaty to phase out ozone-depleting substances has, by healing the hole in the ozone layer, protected human health, economies and ecosystems.

"The cooperation we have seen under the Montreal Protocol is exactly what is needed now to take on climate change, an equally existential threat to our societies", he said.

Until the protocol, old equipment such as building insulation foam, fridge-freezers and other cooling systems, were manufactured using ozone-destroying chlorofluorocarbons, or CFCs, which leaked the damaging gas into the atmosphere as equipment deteriorated.

Other critical services

This year's World Ozone Day highlights that the landmark environmental agreement also slows down climate change and helps to boost energy efficiency for cooling products such as freezers, which then also contributes to food security.

"The Montreal Protocol is more than just an example of how multilateralism can and should work, it is an active tool to help meet our global vision for sustainable development", said the .

And under the Kigali Amendment to the Protocol, nations have committed to phase down hydrofluorocarbons (HFCs), powerful greenhouse gases used as coolants, which are less harmful than CFCs as they contain hydrogen, but are nonetheless still an ozone risk.

When fully implemented, the Kigali Amendment could prevent 0.4 degrees Celsius of global warming this century.

"Furthermore, as we prepare for the Food Systems Summit this month, we are reminded that the Kigali Amendment can also help us to increase food security", flagged Mr. Guterres, explaining that by reducing HFCs, increasing energy efficiency and creating more ozone and climate-friendly technologies, "the Kigali Amendment can bring sustainable access to vital cooling services to millions of people".

These services would reduce food loss in developing countries, where it often spoils before reaching markets.

Getting produce from farmers to where it is needed would, in turn, help reduce hunger, poverty and the environmental impact of the agricultural sector.

Another important benefit of expanding access to safe cooling systems, is to store medicines and vaccines, including those needed to end the COVID-19 pandemic.

"The Montreal Protocol and the Kigali Amendment show us that by acting together, anything is possible", said the . "So let us act now to slow climate change, feed the world's hungry and protect the planet that we all depend on".

Work continues

Although the Montreal Protocol marked "a critical turning point", it was not a one-time fix, according to the UN Environment Programme (UNEP).

The work continues, with scientists still providing the first line of defence.

UNEP leads a joint effort of over 100 governments, businesses and development organizations that supports countries and industry in tackling growing cooling demand, while contributing to the Paris Agreement, Montreal Protocol and Agenda 2030 called the Cool Coalition.

Together with its partners, the Coalition fosters advocacy, knowledge and action to accelerate the global transition to efficient and climate-friendly cooling.

In 1994, through resolution 49/114, the General Assembly proclaimed 16 September as the International Day, commemorating the signing of the Montreal Protocol in 1987.