Ozone layer recovers faster than expected

Scientists on June 12 declared international efforts to protect the ozone layer a "huge global success" after revealing harmful gases in the atmosphere are falling faster than expected.

The Montreal Protocol was signed in 1987 to phase out ozone-depleting substances, mainly found in refrigeration equipment, air conditioners and aerosol sprays.

Graphic of the newly discovered ozone hole over the Arctic. (Photo: BIRA/ESA)

A new study has found that atmospheric levels of hydrochlorofluorocarbons (HCFCs) – the harmful gases that cause holes in the ozone layer – peaked in 2021 – five years earlier than predicted. 'This is a huge global success,' said lead author Luke Western of the University of Bristol in the UK. 'We are seeing things moving in the right direction.'

The most harmful CFCs were phased out in 2010 in an effort to protect the ozone layer – the shield that protects life on Earth from harmful ultraviolet rays from the Sun. The HCFCs that replaced them are expected to be phased out completely by 2040.

The study, published in the journal Nature Climate Change, examined concentrations of these pollutants in the atmosphere using data from the Advanced Global Atmospheric Experiment and the US National Oceanic and Atmospheric Administration.

Mr Western attributes the sharp decline in HCFCs to the effectiveness of the Montreal Protocol , along with tighter national regulations and industry shifts in response to the impending ban on these pollutants. "On the environmental policy front, there is optimism that these environmental agreements can work if they are properly enacted and enforced," he said.

Both CFCs and HCFCs are potent greenhouse gases, meaning their reduction would also help in the fight against global warming. CFCs can persist in the atmosphere for hundreds of years, while HCFCs have a lifespan of about two decades, Western said. Even if they are no longer produced, past use of these products will continue to affect the ozone layer for years to come.

The United Nations Environment Programme estimates that it could take four decades for the ozone layer to recover to levels before the hole was first discovered in the 1980s.