As you can see above, our problem with ozone holes is far from solved. Just last fall, the hole over Antarctica was big enough to swallow North-America… But recent research is showing that this is nothing compared to what we would be facing if not for the Montreal Protocol that went into effect in 1987. Thanks to this international effort to control ozone-depleting substances, 1993 was the peak of their concentration in the atmosphere and they’ve been falling ever since. Problem is, like greenhouse gases, they stick around for a long time, as you can see here:
Study lead author Professor Martyn Chipperfield, from the School of Earth & Environment at the University of Leeds, said: “Our research confirms the importance of the Montreal Protocol and shows that we have already had real benefits. We knew that it would save us from large ozone loss ‘in the future’, but in fact we are already past the point when things would have become noticeably worse.”
How much worse? The researchers suggest that the hole in the ozone layer over the Antarctic would have grown in size by an additional 40% by 2013. Their model also suggests that had ozone-depleting substances continued to increase, the ozone layer would have become significantly thinner over other parts of the globe.
A U.N. report from a few years ago concluded that we could restore the ozone layer to pre-1980 levels by 2045-2060.
If you want to see some real-time info on the ozone hole over the south pole, NASA has a great site called Ozone Watch. Things are looking pretty good recently, but ozone holes are seasonal and can vary quite a bit over the year (getting worse during the Southern Hemisphere spring).
Here’s what things looked like on May 23 (the most recent snapshot):
Much better than the conditions from last fall at the top of this article, eh?
Here’s all the months of October since 1979. You can clearly see a progression of the hole (deep blue) during the 1980s. Clearly, we’re not done dealing with this problem yet:
Finally, the graph below, on the left, shows the progression of last season’s ozone hole over the year: “The gray shading indicates the highest and lowest values measured since 1979. The red numbers are the maximum or minimum observed values. The stratospheric temperature and the amount of sunlight reaching the south polar region control the depth and size of the Antarctic ozone hole.”
The graph on the right shows the variations of ozone from year to year: “The red bars indicate the largest area and the lowest minimum value. The year-to-year fluctuations are superimposed on a trend extending over the last three decades.”
Hopefully someday we can say the same thing about an effective effort to combat greenhouse gas emissions.