[Answered] The ozone ‘hole’, once considered to be the gravest danger to planetary life, is now expected to be completely repaired by 2066. What are the factors that are contributing to its recovery?

Ozone (O3) is found mainly in the stratosphere, between 10 and 50 km from the Earth’s surface. It absorbs ultraviolet rays coming from the Sun. The latest scientific assessment has said that if current policies continued to be implemented, the ozone layer was expected to recover to 1980 values by 2066 over Antarctica, by 2045 over the Arctic, and by 2040 for the rest of the world.

The following factors are contributing to the recovery of ozone hole:

• Montreal Protocol: It banned man-made gases that damage the fragile high-altitude ozone layer, found long-term decreases in the atmospheric abundance of controlled ozone-depleting substances and the ongoing recovery of stratospheric ozone. It’s the only UN treaty that has been ratified by all 198 UN member states.
• This progress over the past three decades was achieved by international compliance with controls on production and trade of ozone-depleting substances.
• In 2019, the protocol was strengthened with the ratification of theKigali Agreement which limits the production of hydrofluorocarbons (HFCs), ozone safe compounds that are potent greenhouse gases.
• The assessment has reported that nearly 99 per cent of the substances banned by the Montreal Protocol have now been eliminated from use. The elimination of ozone-depleting substances has an important climate change co-benefit as well.

The Montreal Protocol has done much more than shrink the ozone hole; it has shown how environmental governance can respond to science, and how countries can come together to address a shared vulnerability. The same spirit of common cause and greater leadership to implement the Paris Agreement on climate change is the need of the hour.