Ozone Hole still getting bigger

Just when we thought it was getting smaller, the hole in the ozone layer has reached record proportions.

Between 21 and 30 September, the average area of the hole reached 27.5 million square kilometres (4 times the area of Australia), according to scientists monitoring ozone levels over the South Pole using NASA's Aura satellite and balloon-borne instruments. This marks an increase of roughly 3.9 million square kilometres from last year.

The blip is due to colder-than-average stratospheric temperatures in the preceding months, explains atmospheric scientist Paul Newman at NASA's Goddard Space Flight Center in Greenbelt, Maryland. Although human production of substances that damage the ozone layer has dropped, the gases are still at peak levels in the stratosphere, and lower temperatures enhance the reactions that produce ozone-depleting chlorine and bromine. We won't see the effects of the drop until about 2024 because the gases have such a long lifetime, says Newman.

"The good news is that human activity isn't making the hole any worse," says Newman. "But we are vulnerable to changes in the weather and that's bad news for people living in the southern hemisphere."

From New Scientist