Ozone hole lingers despite CFC ban
Dark blue in this image represents the hole in the ozone layer over Antarctica, as seen from the satellite Aura in 2005.
DB: This is Earth and Sky, on the recovery of Earth’s protective ozone layer.
JB: Each year, from August to December, ozone is broken down in the stratosphere above Antarctica. This is the famous ozone hole – an area about three times bigger than the United States.
DB: The Montreal Protocol phased out the production of most ozone depleting chemicals in developed countries as long ago as 1996. But scientists have measured little change in the peak size of the ozone hole over the last nine years. We spoke to atmospheric chemist Dale Hurst of the Earth System Research Laboratory in Boulder.
Dale Hurst: Since the downturn in the amounts of ozone-depleting chemicals in the atmosphere occurred about a decade ago, ozone is not responding quickly to this, because … these gases, once they’re released to the atmosphere, they hang around for 50 to 100 years. So, it’s not likely that ozone is going to rapidly respond to a decline in the amount of ozone-depleting chemicals in the atmosphere.
JB: Hurst added that there are uncertainties in the amount of ozone-depleting chemicals still manufactured in developing countries and those held in reservoirs. Researchers had predicted the year 2050 for the recovery of Earth’s ozone layer. But the recovery could take longer.
DB: Thanks today to NOAA – the National Oceanic and Atmospheric Administration. We’re Block and Byrd for Earth and Sky.
Antarctic ozone – not a hole lot worse or better
Ozone hole prospects for recovery, from the December 2005 American Geophysical Union meeting.
United Nations Development Program
The Vienna Convention and the Montreal Protocol
Additional Teacher Resources
EPA: Ozone Science: The Facts Behind the Phaseout
The Earths ozone layer protects all life from the suns harmful radiation, but human activities have damaged this shield. Less protection from ultraviolet light will, over time, lead to higher skin cancer and cataract rates and crop damage. The U.S., in cooperation with over 160 other countries, is phasing out the production of ozone-depleting substances in an effort to safeguard the ozone layer.
NASA: Good News and a Puzzle
Think of the ozone layer as Earths sunglasses, protecting life on the surface from the harmful glare of the suns strongest ultraviolet rays, which can cause skin cancer and other maladies.
