Images of the ozone hole show how, once at least, international environmental negotiations actually succeeded.
If you were a child in the 1980s, it's a good chance that your introduction to "environmental" issues was the ozone hole. This problem is not to be confused with global warming or climate change, though plenty of folks confuse the two. Ozone is often called "nature's sunscreen," as it protects humans from dangerous levels of the sun's ultraviolet rays. But sometime in the latter half of the 20th century, humans started using chlorofluorocarbons ("CFCs," remember those?) in aerosols, which has the unintended effect of stripping away the vital ozone layer.
These NASA images (click through for a bigger image) show ozone levels over Antartctica—where the notorious hole has formed—from 1979 through last October. Blue is bad and purple is worst. The images are all taken on the day of the ozone layer's maximum depletion each year.
A typical knee jerk reaction when seeing these images might be: It still looks pretty big. I thought we'd solved this. And while it doesn't look like there's been much improvement since 1989, the fact that the hole didn't get any worse is a considerable achievement. And from 2006 to 2010 there is actually a little sign of improvement. (More blue, less purple.)
Remember, it was in 1989 that world leaders got serious about combating ozone depletion, and successfully negotiated the Montreal Protocol, an international treaty to phase out ozone-depleting chemicals.
In the world international climate negotiations, The Montreal Protocol process is often held up as a success story, an example of how international environmental diplomacy works. It's important to remember, though, that solving ozone depletion basically meant forcing industry to find chemical replacements for CFCs. A tough sell for pro-business political forces, but a relatively easy fix. Solving the climate crisis involves an entire economy-wide shift in energy production.
Still, the process worked, which is at least a little bit encouraging. Even if, as these images reveal, we still do have a hole in our ozone layer, leaders worldwide agreed to stop its spread and limit its impact, and it's slowly but surely on the mend. We should hope our atmosphere has a similar chance for recovery.