Ozone hole September 10, 2014. Source: NASA (http://ozonewatch.gsfc.nasa.gov/)
A couple days ago I found the triumphal message that the Ozone layer is recovering for the first time in 35 years. Attributed to the Montreal protocol. The brunt of the article was that, we people, can solve environmental problems and finally we could do the same thing with for example global warming. However in the article it is cautioned that it still is a “very brittle recovery”.
I had a hard time understanding this “recovery”. Not that long ago, at the end of last year, NASA revealed new results from inside the Ozone hole, in which was stated that the variation of the Ozone hole was mainly caused by natural processes like wind, temperature, solar radiation, and only for a small part by (anthropogenic) substances like CFC and HFC. It would take still decades before a recovery could be attributed to those diminishing substances.
Beginning this year there also was quite some commotion about new substances being found that attack the Ozone layer.
So where is this “recovery” coming from so suddenly? Telling to me was the “for the first time” and “brittle recovery” quotes. As far as I know the Ozone hole is very variable from year to year. In 2006 the Ozone hole grew larger than ever. The next year, in 2007, it was again an average sized. Surprisingly this “recovery” was also attributed to the Montreal convention. Was it a surprise that at that time it was 20 years ago that the Montreal treaty was signed…
Later in 2011 there was a new low, just above 2006 levels, but only a year later, in 2012, we had the second smallest hole in two decades. This recovery was attributed to “natural variation”. This could obviously not be attributed to the Montreal treaty without raising some hard questions…
But let me rephrase this part of history.
There was a change from the biggest Ozone hole to an average in just one year (2006-2007). Even more telling, several years after this the Ozone hole grew again to almost 2006 levels. It also took just one year (2011-2012) to change from the second biggest to the second smallest of two decades. This means that the natural variability of the Ozone hole is HHHUUUGGGEEE! Now we have the message that “for the first time in 35 years”, some “signs of recovery” were found and Hooray, Hooray, the Montreal treaty is a gigantic success story!
Really?
REALLY?!?!
My guess is they use different metrics that lend more to a hooray story, more than the metrics that they have been using until now to describe the problem (area of the Ozone “hole”). This is misrepresenting the issue to the media/public/politicians who still think the authors of this story are talking about the recovery of the area of the Ozone hole, meaning the ozone hole is getting smaller. Yet, even when this would be the case, that would be quite meaningless because of the large natural variability the Ozone layer showed in the past observations.
This is not something new. There were triumphal stories about the “recovery” of the Ozone Hole several times in the past. All praising international action and saying we could tackle other environmental problems too. Humbled by reality afterwards.
This obviously is a political message and we should remember it as such.
Update
For what it is worth, I found some more information at AP – Scientists say the ozone layer is recovering:
For the first time in 35 years, scientists were able to confirm a statistically significant and sustained increase in stratospheric ozone, which shields the planet from solar radiation that causes skin cancer, crop damage and other problems.
From 2000 to 2013, ozone levels climbed 4 percent in the key mid-northern latitudes at about 30 miles up, said NASA scientist Paul A. Newman. He co-chaired the every-four-years ozone assessment by 300 scientists, released at the United Nations.
That could explain a lot. These scientists seem to be talking about Ozone levels in the atmosphere at mid-northern latitude. Hey, what are those key mid-northern latitudes? When we think about the problem with the ozone layer, we think about the Ozone hole in the Southern hemisphere. As far as I know the problem with the Ozone layer is at the Southern pole, not at the mid-northern latitudes where the scientists seems to have found a 4% improvement in 14 years. So, we get the impression that it is getting solved while the real issue is still there.
I find it hard to track down the origin of this information. Maybe try again later.
Trust, yet verify 