Slashdot Mirror
Antarctic Ozone Hole Leveling Off
twistedfuck writes: "An Irish Time article reports that the size of the hole in the antartican ozone layer is levelling off and should begin reducing in size. It seems like it should be welcome news but it is tempered by the fact that more UV radiation will reach the southern hemisphere this year because the hole will persist longer. Unfortunately I can not find any details regarding the NOAA report on their website." Update: 11/06 17:31 GMT by H :Thanks to Isaac Lewis, NOAA Sysadmin and Slashdot reader, for pointing out more information, as well as pointing out the ozonelayer site.
To summarise the findings, it seems the density of Chlorine from CFCs has peaked, and it is expected the Ozone hole will gradually (i.e. over the next 50 years!) disappear.
It now seems to be an interesting case of us screwing up our environment, working out what we'd done, and fixing it. However, you could consider that we just 'got lucky':
Compare this with the current situation re global warming, and this looks less like a successful victory and more like a warning shot across the bows
Last summer I did some educational outreach for the lab I work for, at a day-camp for science kids, and the topic was ozone one day. If I remember correctly regulation can't possibly account for this, because the CFC's have a destructive lifetime in the atmosphere for something on the order of 100 years. ie. the little buggers break apart O-3 for a long time after we stop using them. Even if we stopped all CFC use today, we wouldn't see any atmospheric effect for many decades. Begging the question: why IS the hole reducing?
Getting diabetes AND salmonella would be a bad weekend.
Speaking as a New Zealander. The Sun and Heat here are probably unlike anything most people have felt. Burn time in the summer comes down as low as 10 minutes. You can't even get in your car and go for a drive without getting burnt. In mid summer you literally have to put on a top with long sleeves or your arms will physically hurt if you are out in the sun
Normal people worry me!
A good description of the process which results in the ozone hole can be found here.
Basically, the intense cold of an antarctic winter creates a vortex which isolates the air over the south pole, and allows build up of the CFCs. When the summer comes, the Chlorine from the CFCs acts as a catalyst to destroy the ozone.
It now seems to be well understood - but it's one of those things that nobody could have predicted before it happened.
Actually, the environment at the time of the dinosaurs was hugely different. Earth had no polar ice caps, and the continents were arranged differently. In the dinosarus' heyday around the middle of the Jurassic, the Atlantic Ocean didn't exist. The bulk of the land was grouped into an enormous crescent surrounding what is now the Indian Ocean. The coasts were warm and humid; the continental interior was desert. It was a world utterly unlike that we live in today, and we probably could not have flourished in it.
And the brethren went away edified.
The ozone hole and CFC sitatuion is one of the most well understood things in science however. It's due to the following:
Based on the equatorial cycle, one would expect to be free of CFC effects after about 100 years - I guess it's been about 25? So I guess this is about when one would start to notice the effects.
Although there are the occasional puppets who still denounce ozone problems, the industries and governments were immediately convinced by the evidence, which is why humans have probably fought off this problem.
Finally, the CO2 issue is a global warming thing, which isn't really related to the ozone hole problem. That's a polar icecap melting problem, and the data is still not totally convincing---the problem is that some predictions say that it's too late to prevent a 1m rise in sea level.
Where is the evidence of the increase of human skin cancers due to "ozone hole" ?
Check cancer rates between Pennsylvania, USA and Sydney, Australia. I know this is far from a bulletproof arguement, for maybe Aussies are naturally more prone to skin cancer, or spend more time outdoors (which they do), or they use a sunblock which mutates them into sun cancer prone mutant freaks. But the (abeit weak) arguement some people say is that in the land down under there is mommothian awareness of skin cancer, everyone uses sun block, hats and that disgusting blue crap you put on your nose, there are advertisements all the time for sun awareness (remember that egg me no fry ad? Yes!), and here in the good old US of A we suffice with those annoying no-life weather channel dorks to tell us to put on a hat. I have lived in both countries for a decent (over 4 years) amount of time and the amount of people here in the US who care about skin cancer is miniscule compared to Aust. Yet (and the reason for that) rates are still higher down there. We are both about on the +/-40 degree latitude mark. This evidence is circumstantial at best but I'm sure someone else can post up a more scientific explanation for it (please?)
Just what I think, thats all
CO2 is responsible for global warming, not ozone depletion.
CFCs (chlorofluorocarbons) and some other gases like halon(tm?) are responsible for the thinning ozone. Most of these gases have been banned under the Montreal protocol for some years now, but because they are largely inert they can rise far into the stratosphere (which takes them quite a few years) where they do their damage. What happens up there is that the suns intense UV rays break the CFC molecules up and the chlorine ends up binding with an oxygen atom from the ozone. The actual reaction is here
CO2, on the other hand, absorbs infrared radiation from the earth reradiated from sunlight and keeps the heat in the atmosphere. It basically acts like a big blanket. CO2 is what the Kyoto Protocol is trying to limit.
---
I didn't want to leave this space blank.