[TheBagman]

The Ozone Layer's Unwelcome Return? -- Berardelli 2008 (612): 2 -- ScienceNOW

The Ozone Layer's Unwelcome Return?

By Phil Berardelli
ScienceNOW Daily News
12 June 2008
Once greeted as good news, the recovery of the ozone layer is increasingly seen as a mixed blessing. In April, researchers found that a healing ozone hole could amplify global warming by trapping more heat in the atmosphere (ScienceNOW, 24 April). And in tomorrow's issue of Science, climatologists report that ozone recovery could disrupt wind patterns in the Southern Hemisphere, potentially leading to a warming of Antarctica. The findings suggest that actions taken by humans to protect the planet from the harmful effects of solar radiation could accelerate climate change on the frozen continent.

Ever since most nations signed the 1987 Montreal Protocol, which banned the manufacture of ozone-destroying chemicals called chlorofluorocarbons, the fragile ozone layer has been set on a slow path to recovery. The layer's return to health is estimated to take another 60 years. By then, the so-called ozone hole should no longer appear over Antarctica every polar spring and persist until autumn. And the cancer-causing ultraviolet (UV) rays that ozone filters out of sunlight will largely be blocked from hitting the surface.

But there's a catch. The appearance of the ozone hole actually created a unique wind pattern called the Southern Annular Mode (SAM), which prevents warmer air from reaching Antarctica. The pattern results from two competing conditions: a cooling of the stratosphere, 12 to 50 kilometers above Earth's surface, due to the depletion of its heat-absorbing ozone layer; and a warming troposphere, which lies below the stratosphere and which has seen its temperature rise thanks to greenhouse-gas accumulation.

As the ozone hole recovers, the stratosphere will once again warm up over the Southern Hemisphere, with unpredictable effects on SAM. In the new study, an international team of researchers compared standard climate change computer models with newer versions that take atmospheric chemistry into account. The comparison showed that ozone-induced stratospheric warming could reduce the role of SAM in blocking tropical air from migrating to the pole. That's worrisome, the team says, because the wind pattern affects, among other things, the Southern Hemisphere's climate, the extent of its sea ice, the variability of its storm tracks, and its patterns of rainfall and drought.

Monitoring ozone's effects will be critical to making future climate change predictions, says atmospheric scientist Judith Perlwitz of the University of Colorado, Boulder. As to how a dwindling SAM will affect Antarctica, Perlwitz says it's impossible to know exactly what will happen: "We can't draw conclusions right now."

[AnnonUSA]

Damned if we do, damned if we don't....

[gilligan]

Time to break out the CFCs!!

[elroypornlab]

Silly us told we should save the ozone layer

[katchafire]

well I hope they save the ozone Im sick of frying out in the sun, seriously its like 3 mins out in the sun over here and you get some serious sun burn. Its crazy and visitors to NZ dont understand until they visit and get crispy fried on their first day here.