Beth Slaninka

There was some encouraging news for the planet last week: the ozone layer is recovering.

The gaseous layer, which protects the Earth from harmful levels of the sun’s ultraviolet rays, is expected to recover by 2050, according to the Scientific Assessment of Ozone Depletion 2014, published September 10 by the UN Environment Programme (UNEP) and the UN World Meteorological Organization (WMO).

A NASA image of the ozone layer over the past 35 years. Associated Press

A NASA image of the ozone layer over the past three decades.

The nearly 300 scientists in 36 countries that prepared and reviewed the report attributed the rebuilding of the ozone layer to the 1987 Montreal Protocol.  In the mid-1970s, scientists found that the stratospheric ozone layer was depleting because of the emission of chlorofluorocarbons (CFCs) found in aerosols, refrigerants, solvents, and foam-blowing agents. Since 1987, 191 countries have signed the international agreement and committed to reducing and eliminating ozone-depleting substances.

“There are positive indications that the ozone layer is on track to recovery towards the middle of the century. The Montreal Protocol—one of the world’s most successful environmental treaties—has protected the stratospheric ozone layer and avoided enhanced UV radiation reaching the [E]arth’s surface,” UN Under-Secretary-General and UNEP Executive Director Achim Steiner said in a news release.

Despite the encouraging news, the report’s key findings caution that there is still more work that needs to be done to not only repair the ozone layer but also to address climate change going forward. Some of these findings include:

  • Actions taken under the Montreal Protocol are only returning the ozone layer to benchmark 1980 levels. This means that even though the emissions of CFCs have ceased, ozone-depleting substances remain in the atmosphere and as a result the Antarctic ozone hole continues to occur each spring.
  • Ozone-depleting substances were replaced by HFCs (hydrofluorocarbons), many of which are considered potent greenhouse gases. HFCs currently contribute about 0.5 gigatonnes of CO2-equivalent emissions per year and are growing at a rate of 8 percent annually. With no action, HFCs could contribute significantly to climate change over the coming decades.
  • CO2, Nitrous Oxide, and Methane will have an increasing influence on the ozone layer and climate change.  Although CO2 and methane tend to benefit global ozone layers, they are among the most powerful greenhouse gases that trap radiation and contribute to climate change. Nitrous oxide, a byproduct of food production, is both a powerful greenhouse gas and an ozone depleting gas, and is likely to become a larger factor in future ozone depletion.

The success of the Montreal Protocol demonstrates the ability that coordinated international action can drive real environmental change. As WMO Secretary-General Michael Jarraud said, “This [success] should encourage us to display the same level of urgency and unity to tackle the even greater challenge of climate change.”

International leaders are scheduled to meet later this month for a climate summit organized by UN Secretary-General Ban Ki-moon to mobilize action on climate change. Hopefully the demonstrated success of the Montreal Protocol will inspire these leaders to begin work on a meaningful legal agreement to address climate change.