A vast hole in Earth's ozone layer yawns open every summer over Antarctica. Since atmospheric ozone shields us from a lot of ultraviolet radiation, losing it means a lot more mutations. But as bad as that sounds, repairing the hole could mean destroying the planet. Now scientists from Columbia University have discovered that the ozone hole is actually keeping the antarctic cold, slowing the erosion of ice sheets like the Larsen Ice Shelf (pictured), which began to crumble this year due to elevated temperatures. It could be that the hole is all that stands between us and a completely melted south pole.
When the ozone hole is finally closed in about 60 years, thanks to environmental protection laws forbidding emissions that thin the ozone layer, the weather will change dramatically at the pole. According to ScienceNOW:
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.
An article about the researchers' work appears in today's edition of Science. This isn't exactly as ironic as you might think. The only reason the SAM exists is because global warming shifted cold winds from the upper atmosphere down to the lower. Basically, the weather just keeps getting more and more screwed up. Photo by Julian Dowdeswell.