Stratospheric ozone depletion, an environmental crisis in the 1980s, can now be considered an environmental triumph thanks to global cooperation in combating it.
The latest Scientific Assessment of Ozone Depletion, published by the World Meteorological Organization and the United Nations Environment Programme, reports the ozone layer will become restored over the next few decades.
“It is particularly gratifying to report that the ozone layer is on track for recovery to 1980 benchmark levels by mid-century,” says NASA scientist Paul Newman and co-chair of the report. “Many of these early signs of ozone improvements are due to decades of work and contributions by NASA and NOAA instruments and scientists.”
Stratospheric ozone protects life on Earth from harmful UV radiation. For humans, overexposure to UV radiation increases the risk of skin cancer, premature aging of the skin, and cataracts.
A rapid increase in ozone depleting substances in the 1980s caused the ozone layer to thin and led to the formation of the iconic “ozone hole” over Antarctica.
Courtesy of the Montreal Protocol, a global treaty passed in 1987 to phaseout ozone depleting substances like chlorofluorocarbons (commonly found in spray cans and refrigerants at the time), ozone depletion has stopped and may soon reverse course.
“[Total column ozone] has remained relatively unchanged since 2000, but there are recent indications of its future recovery,” says one of the report’s key findings.
Assuming continued global compliance with the Montreal Protocol, the ozone layer is expected to recover to 1980 “benchmark levels” – before significant ozone depletion had begun. Recovery is anticipated “before the middle of the century in mid-latitudes and the Arctic, and somewhat later in the Antarctic”, the report says.
The environmental benefits of ozone layer recovery are profound according to the United Nations Environment Programme. It says the Montreal Protocol will have prevented 2 million cases of skin cancer annually by 2030.
The phaseout of certain ozone depleting substances, which are heat-trapping greenhouse gases, has also benefited the climate (by reducing global warming), the report notes. However, some of the replacements for ozone depleting substances are powerful greenhouse gases themselves. For example, hydrofluorocarbons or HFCs – refrigerants used as replacements for CFCs, are growing at a rate of 7 percent per year.
“Left unabated, [HFCs] can be expected to contribute very significantly to climate change in the next decades,” the report says.