Ozone hole: Why Antarctic wildlife is being ‘sunburnt’

The so-called ‘ozone hole’ doesn’t really start to form until after the Winter circumpolar vortex is in place. One of the consequences is that the stratospheric ozone created in the tropics, and moved pole-wards by the Brewer-Dobson Circulation, creates anomalously-high ozone concentrations outside the vortex. Ozone is effectively metastable, having a short half-life, and can also be photo-catalytically decomposed. This is what happens in the Spring in Antarctica. When the sun comes up over the horizon, halides adsorbed onto ice crystals result in rapid destruction of the ozone that has survived through the darkness of Winter. However, during warm Springs, the vortex may break up early and the hole is minimal in size. In any event, when the vortex does break up, the anomalously high concentration of ozone outside the vortex is able to move in and replace the missing ozone, ending the growth of the ‘ozone hole.’ Low temperature plays an important role in the photo-catalytic destruction of ozone by creating the ice crystals necessary as carriers for the halides. IIRC, Erebus has an unusual amount of fluorine in its emissions. That can exacerbate the problem, but the ice crystals are essential.

I have found very few references to actual Antarctic ground-level UV measurements, almost always suggesting that our concern about biological effects should be focused on ozone as a proxy for UV. However, focusing on the proxy ignores the facts that when the sun is low on the horizon, it’s rays have a longer slant-range than when the sun is overhead, which it never is at those latitudes. Basically, the ozone alarmists are either ignorant of the solar geometry, or choose to ignore it. Either behavior does not speak well for those claiming to be scientists. Additionally, sometimes the solar rays pass through the high concentration of ozone outside the vortex. The situation is more complex than is usually acknowledged.

Many years ago, I wrote a computer model to simulate the ground-level UV concentration based on the solar geometry and ozone measurements from the Total Ozone Mapping Spectrometer. What it showed was that there appeared to be a slight upward drift in surface UV-flux during the times of the year when sunlight (and UV) was weak; however, after the break-up of the vortex, when the sun was higher in the sky and sunlight was stronger, the UV flux was not increasing. That is, when animals might need protection from UV, the UV flux was probably the same as what they had evolved with.