Ozone Recovery Slower Than Expected
http://dsc.discovery.com/news/briefs...tml?source=rss
By Larry O'Hanlon, Discovery News
Dec. 9, 2005 —Despite international laws banning ozone destroying chemicals, they are still seeping out of the U.S. and Canada at surprising rates and delaying the recovery of ozone holes at both poles by up to 15 years, say ozone researchers.
CFCs (Chlorofluorocarbons) and other long-lived halon gases used in older refrigerators, fire extinguishers and other devices have been detected by low-flying aircraft surveys of both the U.S. and Canada, which could mean there is a larger reservoir of the now-banned compounds out there.
"Are we underestimating the amount of these chemicals?" asked Dale Hurst of the National Oceanic and Atmospheric Administration’s Earth System Laboratory.
Hurst and other ozone researchers announced changes in their previous, more optimistic estimates of ozone recovery this week at the meeting of the American Geophysical Union in San Francisco.
Back in 2003, ozone researchers were optimistic that CFC emissions were swiftly declining in developing countries where the manufacture of CFCs has long been banned, and that the ozone destruction that happens in the stratosphere above Antarctica and the Arctic would steadily subside by the year 2050.
And while CFCs are, indeed, declining worldwide, they are doing so more gradually than expected, which is why the researchers are now pushing the ozone recovery date to at least 2065.
"That's about 15 years later than the current WMO estimate," said John Austin of the National Oceanic and Atmospheric Administration.
As for how long the U.S. and Canada will be leaking CFCs, that's very hard to say.
"The emissions from these reserves may be significant into the future," said Hurst.
It's impossible to know how much of the ozone-eating stuff is still being held in machines and tanks in the U.S. and Canada, how much is being recycled and how much as been released into the air.
So what can be done?
"I'm not sure there's a lot we can do," said NASA ozone researcher Paul Newman. The chemicals are already heavily regulated, so more policy changes are unlikely to have any effect, he said.
On the other hand, the larger picture of what's happening to stratospheric ozone is pretty good, said Michelle Santee of NASA's Jet Propulsion Laboratory.
Measurements of stratospheric chlorine — the component of CFCs that destroys ozone — are showing a steady decline. And that means the changes made in CFC production worldwide in the 1980s have been worthwhile and are making a measurable difference.
Reply With Quote