The Science Behind the Phase-Out of R-22 Air Conditioner Refrigerant
This is going to be a short article, mainly just providing a quick summary and some links to the ozone depletion work of the US National Oceanic and Atmospheric Administration (NOAA). In the article I wrote last week about dry-ship R-22 air conditioners and heat pumps, a couple of commenters questioned the science behind ozone depletion. As a physicist, I have respect for legitimate questions being raised. I also have concern about the way science gets abused and turned on its ear by those who want to create confusion that leads to inaction. It's happened over and over. Just look at the history of tobacco, global warming, and acid rain. Denial and obfuscation are the main tools of those who want to prevent or delay action.
It's no different with ozone depletion. The science says one thing. The deniers say things that sound reasonable on the surface but don't hold up under the light of scientific scrutiny. Scientists and the NOAA have been on this issue for a long time now, and one of the great things about the Web is that you can easily get access to documents that can dispel the myths. I'll just make two points here and then let you read the NOAA information if you want to know more.
Ozone depletion is real and caused by us
Ozone depletion occurs in two forms: the general reduction of ozone in the stratosphere and the ozone hole, which appears over the poles each spring. The Antarctic ozone hole is the biggest and has appeared each year without fail since 1980. The ozone levels there have dropped to half what they were in 1980, as the graph below illustrates.
How can the chlorine given off naturally by the oceans explains this? It can't. Since it's been stable while the stratospheric ozone has decreased, there's no correlation. A lot of scientific research has gone into understanding what's happening here, and the connection between the stuff we've been putting into the air and the loss of ozone in the upper atmosphere is rock solid.
The Montreal Protocol is working
In 1987, an international meeting produced the Montreal Protocol for reducing emissions of ozone-depleting substances (ODSs). The first step was to eliminate CFCs and replace them with HCFCs, which were much friendlier to the ozone but still not benign. The next step was to replace HCFCs with even more ozone-friendly substances like HFCs. Here's a graph showing the effect of the Montreal Protocol on emissions.
If you look at the executive summary of the 2010 ozone depletion report, you'll see that for the first time, CFC-12—one of the real baddies—has decreased in the troposhere for the first time since they started monitoring ozone-depleting substances. HCFC-22 (the R-22 used in air conditioners), on the other hand, "increased more than 50% faster in 2007-2008 than in 2003-2004." The big picture looks better, but we still need to close the loophole on dry-ship R-22 air conditioners and heat pumps.
Where to go for more info
The science is solid here. Since Rowland and Molina first discovered ozone depletion and its connection to the stuff we put in the air way back in 1974, scientists have learned more and more about our connection to the environment. Of course, you can choose not to believe it. Just take your seat next to the flat earthers in the corner over there.