NASA—Goddard Space Flight Center/Scientific Visualization Studio
Is the Ozone Layer Finally Healing Itself?
Earth isِ currentlyِ experiencing a host ofِ environmental problems.
Air andِ water pollution continue toِ plague muchِ of theِ world; exotic plants, animals, andِ other organisms pop upِ inِ parts ofِ the globe thatِ haveِ no natural defense againstِ them; and, allِ the while, climate change lingers inِ the headlines.
It’s oftenِ difficult toِ find good environmental news, butِ environmentalists andِ scientists haveِ reported oneِ bright spot: theِ countries ofِ the world rallying toِ combat theِ problem ofِ ozone depletion.
Earth’s protective ozone layer sits someِ 15 toِ 35 km 9 toِ 22 miles] above Earth’s surface, inِ the stratosphere.
Stratospheric ozone loss isِ worrisome becauseِ the ozone layer effectively blocks certainِ types ofِ ultraviolet (UV) radiation andِ other forms ofِ radiation thatِ couldِ injure orِ kill mostِ living things.
However, scientists stillِ couldِ not sayِ whether theseِ efforts wereِ helping.
Sherwood Rowland andِ Dutch chemist Paul Crutzen discovered thatِ human-produced CFCs couldِ beِ a major source ofِ chlorine inِ the stratosphere.
They alsoِ noted thatِ chlorine couldِ destroy extensive amounts ofِ ozone afterِ it wasِ liberated fromِ CFCs byِ UV radiation.
Since then, scientists haveِ tracked howِ the ozone layer hasِ responded toِ CFCs, which, sinceِ their creation inِ 1928 hadِ beenِ used asِ refrigerants, cleaners, andِ propellants inِ hairsprays, spray paint, andِ aerosol containers.
In response toِ theِ growing problem, muchِ of theِ world cameِ together inِ 1987 toِ sign theِ Montreal Protocol onِ Substances That Deplete theِ Ozone Layer, an agreement thatِ allowed theِ world toِ beginِ to phase outِ the manufacturing andِ use ofِ CFCs—molecules containingِ only carbon, fluorine, andِ chlorine atoms—and otherِ ODCs.
Follow-up meetings throughoutِ theِ 1990s andِ early 2000s produced amendments aimed atِ limiting, reducing, andِ eliminating hydrobromofluorocarbons (HBFCs), methyl bromide, carbon tetrachloride, trichloroethane, hydrofluorocarbons (HFCs), hydrochlorofluorocarbons (HCFCs), andِ other ODCs.
Even thoughِ nearlyِ allِ of theِ planet’s governments hadِ beenِ working diligently towardِ a common goal—good news inِ itself—it wasِ unclear whetherِ theseِ unprecedented efforts wereِ havingِ much ofِ anِ effect.
In 2014, however, scientists received theِ firstِ bit ofِ good news onِ this topic: theِ firstِ small increases inِ stratospheric ozone inِ more thanِ 20 years hadِ beenِ detected, alongِ with evidence thatِ ODCs hadِ declined byِ 10–15% inِ the atmosphere.
The 2016 study, whichِ tracked theِ evolution ofِ the size ofِ the ozone hole overِ Antarctica, observed thatِ stratospheric ozone concentrations wereِ continuing toِ increase andِ that theِ size ofِ the Antarctic ozone hole hadِ declined byِ half theِ size ofِ the continental U.S.
betweenِ 2000 andِ 2015.