Earth’s protective ozone layer is showing its first signs of recovery, largely because of the 1980s ban on some chemicals used in refrigerants and aerosol cans. The discovery was made by a U.N. scientific panel.
For the first time in 35 years, scientists confirmed a statistically significant and sustained increase in stratospheric ozone, reports ABC News. Levels climbed 4 percent from 2000 to 2013 in the key mid-northern latitudes at about 30 miles up.
Chemist Mario Molina called the finding “a victory for diplomacy and for science and for the fact that we were able to work together.”
The ozone layer began thinning in the late 1970s because of man-made chloroflourocarbons, called CFCs. These chemicals released chlorine and bromine, which destroyed ozone molecules in the atmosphere. Scientists raised the alarm and countries around the world responded by enacting a treaty in 1987 that phased out CFCs.
World Meteorological Organization Secretary-General Michel Jarraud told Reuters of the new ozone layer report:
“International action on the ozone layer is a major environmental success story… This should encourage us to display the same level of urgency and unity to tackle the even greater challenge of tackling climate change.”
Past studies suggested the ozone layer stopped getting worse, and the latest report shows minimal recovery — a big change from a decade ago. The ozone layer was expected to recover toward its 1980 level by mid-century, or slightly later for Antarctica. The protective layer gets dangerously thin over the continent from mid-August through November or December.
WMO senior scientific officer Geir Braathen noted, “The development you saw during the 1990s that the ozone hole got bigger from year to year – that development has stopped, so it has leveled off.”
Braathen added, “We think in about 2025 or thereabouts we’ll be able to say with certainty that the ozone hole is getting smaller.”
Should existing stocks of CFCs be destroyed, progress could be sped up by as much as 11 years. The largest ozone hole on record was about 30 million square kilometers and was recorded in 2006. The hole now covers about 20 million square km.
While CFCs have been banned and the ozone layer is healing, the chemicals that replaced CFCs have been found to contribute to global warming. MIT atmospheric scientists Susan Solomon explained that they don’t make a big impact right now. However, they are expected to increase dramatically by mid-century and make a “big contribution” to climate change.
The United Nations announced earlier this week that atmospheric levels of carbon dioxide, the main greenhouse gas, surged to another record high last year. The increase from 2012 was the biggest jump in 30 years.
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