Findings presented at the recent International Polar Year (IPY) conference in Oslo, Norway, offer an explanation for Antarctic sea ice levels that have paradoxically grown over the last three decades despite a warming Earth, reports LiveScience.

The explanation, however, is laced with an irony that may be difficult for environmentalists to swallow.

It turns out that the hole in the ozone layer — that ominous target of environmental concern in the '80s and early '90s — may be the only thing left protecting the Antarctic from succumbing to global warming.

The infamous ozone hole, which sits atop Antarctica, has been steadily shrinking since 1989 when ozone-depleting chemicals were banned by the Montreal Protocol. Trumpeted as a triumph for the environmental movement, scientists now predict that the ozone hole will be officially sealed by 2060 or 2070, according to the LiveScience article.

A replenished ozone layer is good news for life on Earth — which will be protected from the sun's harmful UV light — but it could also profoundly alter how winds circulate around Antarctica, according to John Turner of the British Antarctic Survey, who presented his research to the conference in Norway. Currently the hole in the ozone layer acts as a huge vent in the atmosphere, keeping chilly Antarctic winds self-contained. As the hole shrinks, warmer winds may be able to break through the Antarctic shield.

Unlike in the Arctic, where the buildup of greenhouse gases in Earth's atmosphere have caused sea ice levels to drop to their lowest levels in recorded history, sea ice surrounding the Antarctic have grown. Until this research revealed how the ozone hole effects wind circulation in Antarctica, the sea ice growth was mostly a mystery.

Turner's research also turned up evidence that Antarctic sea ice was decreasing just as it is in the Arctic before the ozone hole formed. That trend is likely to resume as the ozone hole continues to shrink.

It's important to remember that the ultimate cause of decreasing worldwide sea ice is global warming from the emission of greenhouse gases; it is not due to the depletion of the ozone hole. In other words, efforts to shrink the ozone hole are not the villain.

The findings provide more evidence that the Earth's climate is sensitive, complex, and easily altered by human activity.

Shrinking ozone hole could speed global warming
An eco-paradox: Efforts to repair the hole in the ozone layer may quicken the melting of Antarctic sea ice.