The Earth’s ozone layer is recovering

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For decades, Earth’s ozone layer, which protects life on our planet from the sun’s harmful ultraviolet (UV) rays, has suffered from the common chemicals used in everything from refrigerants to hairspray. But now the holes in the ozone layer are shrinking, thanks to a decades-long global effort to repair them, the World Meteorological Organization (WMO) confirmed yesterday.

Scientists first discovered a gaping hole over Antarctica in 1985. A few years later, countries around the world adopted the Montreal Protocol, a global effort to phase out “ozone-depleting substances.” And now, thanks to that work, scientists expect the ozone layer to become more like its normal, healthy self in the coming decades. This reduces the risk of skin cancer and cataracts in humans, and of sun damage to plants and crops.

Scientists expect the ozone layer to become more like its normal, healthy self in the coming decades

By 2066, the WMO thinks the ozone layer will be back to what it was in 1980 over Antarctica – before there was that gaping hole. Since ozone depletion is most severe there, other areas are expected to recover faster. In the north over the Arctic, the ozone layer should look like it did in 1980 by 2045. For the rest of the world, that recovery is expected by 2040. A United Nations panel of experts presented these findings yesterday at the annual meeting of the American Meteorological Society. . Of course, that progress depends on enforcing policies that curb those pesky ozone-depleting substances.

Ozone molecules in the stratosphere absorb harmful UV-B radiation from the sun, blocking much of it from reaching us. That is part of a process of continuous production and destruction of ozone in our atmosphere. But when certain chemicals surface, that balance is disrupted, destroying more ozone than it creates.

Some of the worst offenders are chlorofluorocarbons (CFCs) that were once used in refrigeration, air conditioning, aerosol cans and a host of other products. Then there are chlorofluorocarbons (HCFCs), developed as less potent replacements for CFCs that nevertheless chewed through the ozone layer. Fortunately, the Montreal Protocol has now succeeded in phasing out about 99 percent of ozone-depleting substances.

The global agreement to protect the ozone layer is also beneficial to climate change mitigation efforts. Substances that deplete the ozone layer were replaced by another class of chemicals that happen to be potent greenhouse gases called hydrofluorocarbons (or HFCs – sorry for all the annoyingly similar acronyms). The Kigali Agreement was added to the Montreal Agreement in 2016 to limit those chemicals that warm the planet. Abolition of HFCs globally is expected to significantly reduce global warming – up to half a degree Celsius by 2100. By comparison, the world has already warmed by about 1.2 degrees Celsius since pre-industrial times – causing much of the extreme weather disasters we live with today are exacerbated.

But there is a climate caveat to the WMO’s good news. The panel of experts warns that “geoengineering” – deliberately manipulating the climate and/or atmosphere to reverse some of the damage we’ve done by burning fossil fuels – may be taking its own toll of the ozone layer. They are particularly concerned about a tactic called stratospheric aerosol injection (SAI).

Nevertheless, the phase-out of ozone-depleting chemicals has been cited as an example of what people can achieve when they work together to tackle a global environmental crisis. “Ozone action sets a precedent for climate action. Our success in phasing out ozone-eating chemicals shows us what can and must be done – urgently – to move away from fossil fuels, reduce greenhouse gas emissions and thus limit temperature rise,” said WMO Secretary General Petteri Taalas in a statement yesterday.

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