Wednesday, October 5, 2011

Arctic Ozone Loss 2011

A timely paper just came out in Nature by Manney et al. (2011) informing us that the Arctic saw an Unprecedented Arctic Ozone Loss in 2011.  Here is their abstract:

"Chemical ozone destruction occurs over both polar regions in local winter–spring. In the Antarctic, essentially complete removal of lower-stratospheric ozone currently results in an ozone hole every year, whereas in the Arctic, ozone loss is highly variable and has until now been much more limited. Here we demonstrate that chemical ozone destruction over the Arctic in early 2011 was—for the first time in the observational record—comparable to that in the Antarctic ozone hole. Unusually long-lasting cold conditions in the Arctic lower stratosphere led to persistent enhancement in ozone-destroying forms of chlorine and to unprecedented ozone loss, which exceeded 80 per cent over 18–20 kilometres altitude. Our results show that Arctic ozone holes are possible even with temperatures much milder than those in the Antarctic. We cannot at present predict when such severe Arctic ozone depletion may be matched or exceeded."
Remember, the ozone layer is in the stratosphere, which is above the layer where our weather takes place, the troposphere.  A cooling stratosphere and warming troposphere are signatures of "global warming," which is probably better called "global climate change" for this reason.  While the stratosphere had ideal conditions for our very first Arctic ozone hole in spring, the troposphere had ideal conditions for record-low sea ice extent in fall.  More on this newsworthy item later!

I also think it is worth noting that even though we have a global policy to reduce CFC emissions (Montreal Protocol), CFCs have a long lifetime in the atmosphere and those big bangs I was sporting in the 80's and the accompanying hairspray bottle that used CFCs are still around doing damage to the ozone layer.  (Well, the big bangs aren't doing damage, but the CFCs are, you get the idea.)  Carbon dioxide, the culprit for global warming, also has a long lifetime in the atmosphere.

Lastly, the intensity of polar ozone depletion depends on not only CFC concentrations, but the strength of the polar vortex as well as the number of polar stratospheric clouds present.