NASA keeps eye on ozone layer amid Montreal Protocol...( Washington - NASA scientists will jo...)

Washington - NASA scientists will join researchers from around the world to celebrate the 20th anniversary of the Montreal Protocol, an international treaty designed to reduce the hole in Earth's protective ozone layer. The United Nations Environment Program will host the meeting from Sept. 23-26 in Athens, Greece. NASA scientists study climate change and research the timing of the recovery of the ozone layer.

"The Montreal Protocol has been a resounding success," said Richard Stolarski, a speaker at the symposium from NASA's Goddard Space Flight Center, Greenbelt, Md. "The effect can be seen in the leveling off of chlorine compounds in the atmosphere and the beginning of their decline."

Since the Montreal Protocol was signed on Sept. 16, 1987, more than 100 nations have agreed to limit the production and release of compounds, notably human-produced chlorofluorocarbons, known as CFCs. CFCs and a list of other compounds are known to degrade the layer of ozone in the stratosphere that shields life from the sun's ultraviolet radiation. That process gives rise to the ozone hole above Antarctica.

Today, space-based instruments aboard NASA's Aura satellite monitor the chemical make-up of the atmosphere and collect data that will help researchers better understand ozone chemistry through computer models. While the data show that average chlorine levels are beginning to decline, springtime ozone depletion in the polar regions continues to be a prominent atmospheric feature.

"The goal now is to ensure that CFCs and other emissions continue to fall to below the levels that produce an ozone hole," said Goddard's Anne Douglass, the deputy project scientist for Aura. "This won't happen until about 2070."

NASA and National Oceanic and Atmospheric Administration scientists announced in 2006 that the hole was the largest ever observed, at 10.6 million square miles. The size of the hole will approach its annual peak in late September
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