Ozone hole recovering thanks to Montreal Protocol, NASA says

There’s concrete proof that the hole in the ozone is recovering, NASA scientists say.

According to a release, there has been a decline in chlorine in the atmosphere, which NASA attributed to the chlorofluorocarbon (CFC) ban set in place (commonly referred to as the Montreal Protocol.)

“Before the Montreal Protocol, ozone-depleting substances at the surface were going up rapidly,” Susan Strahan, an atmospheric scientist at NASA, explained.

“Once the protocol was signed in and those regulations went into effect, we saw at the surface levels of ozone-depleting substances going down.”

Scientists said there has been 20 per cent less ozone depletion during Antarctic winter than there was in 2005, which is when NASA started monitoring the hole.

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Officials said they measured the chemical composition inside the ozone hole to confirm the numbers.

“We see very clearly that chlorine from CFCs is going down in the ozone hole, and that less ozone depletion is occurring because of it,” Strahan said in the release.

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The Montreal Protocol was put in place over 20 years ago and is an international treaty aimed at protecting the ozone layer by phasing out CFCs and other substances responsible for ozone depletion.

CFCs are found in industrial aerosols. When the CFCs enter the upper atmosphere, they break down into other substances, including chlorine which reacts with the oxygen molecules and tears apart the ozone molecule.

Each September, the ozone hole forms over Antarctica. In 2017, the ozone hole was around 20 million square kilometres – which is below the average of 26 million square kilometres. That’s the smallest the ozone hole has been since 1988.