Ozone fights back

[brainsmile]

http://news.yahoo.com/s/nm/20060503/sc_nm/environment_ozone_dc

Ozone layer shows signs of recovery: scientists By Patricia Reaney

LONDON (Reuters) - The ozone layer is showing signs of recovering, thanks to a drop in ozone-depleting chemicals, but it is unlikely to stabilize at pre-1980 levels, researchers said on Wednesday.

Depletion of the earth's protective ozone layer is caused by the chemical action of chlorine and bromine released by man-made chlorofluorocarbons (CFCs), which are used in aerosol sprays and cooling equipment.

Ozone-depleting chemicals were banned by the 1987 Montreal Protocol which has now been ratified by 180 nations.

"We now have some confidence that the ozone layer is responding to the decreases in chlorine levels in the atmosphere due to the leveling off and decrease of CFCs," said Dr Betsy Weatherhead, of the University of Colorado in Boulder.

"Not only is the ozone layer getting better, we feel it is due to the Montreal Protocol," she added in an interview.

The depletion of the ozone layer, which absorbs most of the harmful effects of the sun's ultraviolet radiation, increases the risk of skin cancer and cataracts in humans and may harm crop yields and sea life.

Despite the signs of recovery, Weatherhead, who reported the findings in the journal Nature, said people should still protect themselves from harmful ultraviolet rays.

Weatherhead and Signe Bech Anderson of the Danish Meteorological Institute in Copenhagen analyzed data from satellites and ground stations and information from 14 modeling studies.

They found that ozone levels have stabilized or increased slightly in the past 10 years. But full recovery is still decades away.

The researchers said depletion has been most severe at the poles and to a lesser extent at mid-latitudes covering bands of North America, South America and Europe.

Shifting temperatures, greenhouse gases, nitrous oxide (N20) and atmospheric dynamics, which can influence ozone levels, are going to change in the future, they added.

"Therefore we really don't think ozone is going to stabilize back to its pre-ozone-depleting-substance levels," Weatherhead said.

Volcanic activity on Earth also has an impact. The 1993 Mount Pinatubo eruption in the Philippines caused ozone levels to backslide for several years, according to the researchers.

[Houdini]

Heh...so we found a hole that opens once/year when we developed the technology to look for it. It may have existed and fluctuated for hundreds of years. Or it may have been other places besides Antarctica and parts of New Zealand. It's never really bothered me, especially after consulting some experts several years ago when I wanted to learn more about it. :shrug:

[clutchy]

this sounds like good news.

The guy who won the nobel prize for his research with CFC's and his findings about what was happening to the layer came and spoke at my college a few years back. It was awesome.

[InfiniteNothing]

Heh...so we found a hole that opens once/year when we developed the technology to look for it. It may have existed and fluctuated for hundreds of years. Or it may have been other places besides Antarctica and parts of New Zealand. It's never really bothered me, especially after consulting some experts several years ago when I wanted to learn more about it. :shrug:Aren't you glad we stopped using CFCs in our spray cans though. A single molecule can take out quite a bit of Ozone. Whether we caused it or not, it's in our best interest to do what we can to avoid making the hole bigger.

[ShawnLee]

Heh...so we found a hole that opens once/year when we developed the technology to look for it. It may have existed and fluctuated for hundreds of years. Or it may have been other places besides Antarctica and parts of New Zealand. It's never really bothered me, especially after consulting some experts several years ago when I wanted to learn more about it. :shrug::stupid:
Aren't you glad we stopped using CFCs in our spray cans though. A single molecule can take out quite a bit of Ozone. Whether we caused it or not, it's in our best interest to do what we can to avoid making the hole bigger.:stupid:

I don't think it's the huge problem that people made it out to be when it first came out. I remember the doom and gloom reports, and whatnot. Anyone else remember Robocop and the newscasters talking about wearing SPF 150 because the Ozone layer was gone, or something stupid like that?

That said, a reasonable method of not contributing until we know for sure all the details? Sure.

[Markel]

:stupid:

[Houdini]

Aren't you glad we stopped using CFCs in our spray cans though. A single molecule can take out quite a bit of Ozone. Whether we caused it or not, it's in our best interest to do what we can to avoid making the hole bigger.

Yep. While I don't believe that we caused it, we do know that certain CFCs can eat up ozone based on lab studies. So, sure, I'm happy we did so. Am I completely freaked out if someone vents the AC on their old car with R12? Not really, but I did retrofit my old car, the right way, with R134. Mainly b/c R12 was getting waaay too $$, and I had a small leak that required charging every summer.

For example, if someone wanted to purge the few thousand refrigerators that were discarded after Katrina of their freon, even blowing it into the atmosphere, before torching them and using them to help fill wetlands, build reefs, whatever, I'd have little problem with that. But yes, overall, I think we should do what we can on a global scale to keep stratospheric ozone intact.

[clutchy]

certain CFC's don't break down for 50 years, and other take up to 100 years. That stuff is bad news and IIRC 1 molecule of that stuff can wack up to 100 molecules of ozone...

but the ozone has been recovering happily since they were banned, so no big deal.

[Houdini]

certain CFC's don't break down for 50 years, and other take up to 100 years. That stuff is bad news and IIRC 1 molecule of that stuff can wack up to 100 molecules of ozone...

but the ozone has been recovering happily since they were banned, so no big deal.

I'm not sure one molecule can kill that much ozone, but I don't remember the binding factors. It's been a while. But I suspect it's far less.

I'm also not convinced that the ozone's healing (it was never that big of a deal anyway, as it only opens around October/November) is due to a significant amount, to human use of CFCs. I believe it was likely more of a coincidence. I wouldn't be surprised if it "grows" during our lifetime.

[hapoo]

this sounds like good news.

The guy who won the nobel prize for his research with CFC's and his findings about what was happening to the layer came and spoke at my college a few years back. It was awesome.


That would be my main man Sherwood Rowland. He was a prof at UCI. I have classes in a building named after him.

[InfiniteNothing]

I'm not sure one molecule can kill that much ozone, but I don't remember the binding factors. It's been a while. But I suspect it's far less.

I'm also not convinced that the ozone's healing (it was never that big of a deal anyway, as it only opens around October/November) is due to a significant amount, to human use of CFCs. I believe it was likely more of a coincidence. I wouldn't be surprised if it "grows" during our lifetime.
The correlation between ozone hole and atmospheric chlorinated compounds are pretty well established and generally agreed upon. The number of ozone molecules a CFC can take out is fact. The CFC essentially acts as a catalyst (since ozone is unstable)

When ultraviolet light waves (UV) strike CFC* (CFCl3) molecules in the upper atmosphere, a carbon-chlorine bond breaks, producing a chlorine (Cl) atom. The chlorine atom then reacts with an ozone (O3) molecule breaking it apart and so destroying the ozone. This forms an ordinary oxygen molecule(O2) and a chlorine monoxide (ClO) molecule. Then a free oxygen** atom breaks up the chlorine monoxide. The chlorine is free to repeat the process of destroying more ozone molecules. A single CFC molecule can destroy 100,000 ozone molecules.

http://www.theozonehole.com/ozonedestruction.htm

[Houdini]

The correlation between ozone hole and atmospheric chlorinated compounds are pretty well established and generally agreed upon. The number of ozone molecules a CFC can take out is fact. The CFC essentially acts as a catalyst (since ozone is unstable)
http://www.theozonehole.com/ozonedestruction.htm

I agree that CFC's can take out ozone. I never said they didn't. I'm very familiar with the chem equations, and if I weren't, I could figure them out in about 10 min. But, other things can dramatically influence the hole (which, contrary to popular belief is only open for a little while each year.) Also, as mentioned in that, albeit biased page - just look at the url, for example, other things can hit stratospheric ozone pretty hard as well, like volcanic activity, etc., of which tremendous amounts of gases are released each year, even from underwater geo sources, which really makes me think that the hole has been there for much longer than aerosol cans or freon. We only found the hole b/c we, well, looked for one. That doesn't mean it's new.

[InfiniteNothing]

I agree that CFC's can take out ozone. I never said they didn't. I'm very familiar with the chem equations, and if I weren't, I could figure them out in about 10 min.
I was responding to this:

I'm not sure one molecule can kill that much ozone
I was providing an affirmative. One cfc molecule can destroy 100,000 ozone molecules.
Now in terms of

Also, as mentioned in that, albeit biased page - just look at the url, for example, other things can hit stratospheric ozone pretty hard as well, like volcanic activity, etc., of which tremendous amounts of gases are released each year, even from underwater geo sources, which really makes me think that the hole has been there for much longer than aerosol cans or freon. We only found the hole b/c we, well, looked for one. That doesn't mean it's new.
See EPA info:

How do we know that natural sources are not responsible for ozone depletion?
While it is true that volcanoes and oceans release large amounts of chlorine, the chlorine from these sources is easily dissolved in water and washes out of the atmosphere in rain. In contrast, CFCs are not broken down in the lower atmosphere and do not dissolve in water. The chlorine in these human-made molecules does reach the stratosphere. Measurements show that the increase in stratospheric chlorine since 1985 matches the amount released from CFCs and other ozone-depleting substances produced and released by human activities.
http://www.epa.gov/ozone/science/q_a.html#q3

[MikeD]

Now they say it may be gone completely by 2050. :shrug:


TOKYO - The ozone hole over the Antarctic is likely to begin contracting in the future and may disappear by 2050 because of a reduction in the release of chlorofluorocarbons and other ozone-depleting gases, according to a team of Japanese scientists.

The findings are based on a series of numerical simulations carried out by Eiji Akiyoshi of the National Institute for Environmental Studies, near Tokyo, using projected emissions of chlorofluorocarbons and other gases blamed for the ozone hole.

According to a report posted Friday on the institute’s Web site, the hole is at its largest now but is likely to gradually start contracting around 2020 and disappear by around 2050.

The team’s findings are in line with research by other scientists.

Some, however, have suggested the hole won’t heal until much later because old refrigerators and air-conditioning systems — many in the United States and Canada — are still releasing ozone-killing chemicals. Both countries curbed those chemicals in newer products.

Satellites and ground stations have been monitoring the ozone hole over the South Pole since its discovery in the 1980s.

Chlorofluorocarbon levels in the earth’s atmosphere have been declining since the mid-1990s due to international efforts to reduce emissions.

http://www.msnbc.msn.com/id/12888244/

[InfiniteNothing]

Yeah, that's nothing new. It's always been predicted to disappear if we do our part.

[ramazank2]

I agree that CFC's can take out ozone. I never said they didn't. I'm very familiar with the chem equations, and if I weren't, I could figure them out in about 10 min. But, other things can dramatically influence the hole (which, contrary to popular belief is only open for a little while each year.) Also, as mentioned in that, albeit biased page - just look at the url, for example, other things can hit stratospheric ozone pretty hard as well, like volcanic activity, etc., of which tremendous amounts of gases are released each year, even from underwater geo sources, which really makes me think that the hole has been there for much longer than aerosol cans or freon. We only found the hole b/c we, well, looked for one. That doesn't mean it's new.

You can see correlations here of ClO and Ozone here:
http://remus.jpl.nasa.gov/science.htm

Also in 1990 biogenic sources of chlorine were are ~18%
http://www.ndsc.ncep.noaa.gov/news/freq_qu/faq3.html

NASA and NOAA are reliable sources too...


When ultraviolet light waves (UV) strike CFC* (CFCl3) molecules in the upper atmosphere, a carbon-chlorine bond breaks, producing a chlorine (Cl) atom. The chlorine atom then reacts with an ozone (O3) molecule breaking it apart and so destroying the ozone. This forms an ordinary oxygen molecule(O2) and a chlorine monoxide (ClO) molecule. Then a free oxygen** atom breaks up the chlorine monoxide. The chlorine is free to repeat the process of destroying more ozone molecules. A single CFC molecule can destroy 100,000 ozone molecules.

If you think chlorine is bad you should see Br!! Good thing we dont realease much Br up there.

I've met all 3 1995 nobel prize winners for this topic. (Molina, Rowland, and Crutzen)