Friday, May 7, 2010
Whatever Happened to the Hole in the Ozone Layer?
Three British scientists shocked the world when they revealed on May 16th, 1985 - 25 years ago - that aerosol chemicals, among other factors, had torn a hole in the ozone layer over the South Pole. The ozone layer, which protects life on Earth from damaging solar radiation, became an overnight sensation. And the hole in the ozone layer became the poster-child for mankind's impact on the planet.
Today, the ozone hole - actually a region of thinned ozone, not actually a pure hole - doesn't make headlines like it used to. The size of the hole has stabilized, thanks to decades of aerosol-banning legislation. But, scientists warn, some danger still remains.
First, the good news: Since the 1989 Montreal Protocol banned the use of ozone-depleting chemicals worldwide, the ozone hole has stopped growing. Additionally, the ozone layer is blocking more cancer-causing radiation than any time in a decade because its average thickness has increased, according to a 2006 United Nations report. Atmospheric levels of ozone-depleting chemicals have reached their lowest levels since peaking in the 1990s, and the hole has begun to shrink.
Now the bad news: The ozone layer has also thinned over the North Pole. This thinning is predicted to continue for the next 15 years due to weather-related phenomena that scientists still cannot fully explain, according to the same UN report . And, repairing the ozone hole over the South Pole will take longer than previously expected, and won't finish until between 2060 and 2075. Scientists now understand that the size of the ozone hole varies dramatically from year to year, which complicates attempts to accurately predict the hole's future size.
Interestingly, recent studies have shown that the size of the ozone hole affects the global temperature. Closing the ozone hole actually speeds up the melting of the polar ice caps, according to a 2009 study from Scientific Committee on Antarctic Research.
So even though environmentally friendly laws have successfully reversed the trend of ozone depletion, the lingering effects of aerosol use, and the link between the ozone hole and global warming, virtually ensure that this problem will persist until the end of the century.