Talk:Ozone depletion
Ed, I moved your links around. I moved the "opposing" links to the bottom (if the links are going to oppose something-- which they have every right do to-- it sort of makes sense to first present that which they oppose, I figured.) I also felt that it was strange to classify the prevailing scientific opinion as the "environmentalist position"... I suppose you might automatically classify as "environmentalist" all chemists and atmospheric scientists who believe in the damaging environmental effects of CFCs-- but such a definition seems rather circular.
Sorry, if it's indeed the prevailing scientific opinion it should be labeled that way. But even then, if scientists are divided on an issue, a pro-con division would be better than a scientists-sceptics division. As an educated layman, I know what the standard of scientific proof is, and if a public policy organization claims that a certain cause would increase the incidence a bad thing (like cancer), there should be evidence of this, not just predictions.
- There's nothing wrong with pro and con. I just wanted you to point out that both positions are scientific theories, not "environmentalist" or "anti-environmentalist" theories (which you did, so I apologize for beating a dead horse.) Some scientists who accept the CFC-theory on the basis of the evidence may drive to work in big gas guzzling trucks and hose their lawn with contraband DDT. The fact that environmentalists happen to agree with the scientific theory is relevant, but it does not define the theory (anymore than the fact that deodorant-can manufacturers probably agreed with the opposing side at the time makes Mr. Singer's theories the "Deodorant-can manufacturer" position.) I do think it's useful if it's made clear that one particular view is seen as the prevailing scientific view... This doesn't make the scientists on that side "right", but it helps explain why people (like government agencies) tend to come down on one side.
The articles on ozone and CFCs need data on measured UV radiation, incidence of cancer, ozone levels, and CFC levels. Then a hypothesis linking them. Then testing and confirmation of the hypothesis. Anything less than this is not science but advocacy. Agreed? Ed Poor
- I agree, but as you've seen, it's often in the interpretation of observed fact where problems appear. I don't know if any of us here have sufficient knowledge to prove or disprove any hypothesis, no matter how much information we're able to gather. For instance, I find string theory to be a very cool idea, and I can dig up facts and write articles about it. But in the end, I'm probably going to have to rely on other people's processed arguments to determine whether it's for real, or if it's just a bunch of baloney. -D
Your latest change is a distinct improvement. Thanks. --Ed
I changed it some more, and you changed it some more. I think, given the little I actually know, that I should leave it the way you left it, D.
I would like to mention some of Singer's points, as follows:
- The major public concern about a possible depletion of ozone comes from the fear that solar UV-B (280-320 nm) radiation reaching the surface will increase, typically by 10%.
- Yet UV-B intensity increases naturally by about 5000% between pole and equator; there is less ozone traversed when the sun is closer to the zenith (32).
- Hence a 10% increase at mid-latitudes translates into moving 60 miles (100 km) to the south, hardly a source for health concerns.
Would someone please least at least one scientist who supports the CFC-ozone-UV-cancer hypothesis? I already know that the UNEP, a public policy advocacy organization, believes in it. But does anyone know what scientific work they base their position on? Please name names of scientists and their university or other affiliation. Ed Poor
I did an Altavista search for "increasd UV radiation" and got Columbia University's web page. It looks pretty scientific to my, but I haven't double-checked their footnotes. Also the latest info cited is 12 years old. Here's a quote: Ed Poor
- Substantial reductions of up to 50% in the ozone column observed in the austral spring over Antarctica and first reported in 1985 (Farman et al 1985) are continuing (SORG 1990). Coupled with this there has been a statistically significant downward trend in wintertime total ozone over the northern hemisphere of about 2-3% per decade for the past 30 years, although summertime ozone levels have remained approximately constant (Frederick 1990). In its report in June 1990, the UK Stratospheric Ozone Review Group concluded that there are serious limitations in our understanding and ability to quantify ozone depletion at the present levels of contaminant release and in our ability to predict the effects on stratospheric ozone of any further increases (SORG 1990).
Increased UV has been measured at Earth's surface--notably in Toronto, and I'll have to see if I can verify my memory that the Chilean city is Punta Arenas. I changed the text accordingly: solid measurements exist, it simply isn't true to say "scientists have not measured" this.
- Yes, Punta Arenas. It's a high enough latitude that the increased radiation doesn't equal a huge risk yet--but it is exactly the evidence being asked for, of increased UV reaching Earth's surface because of ozone depletion. A lot of the relevant papers, unfortunately, are in Portuguese--is there someone here who can read that? A little quick work with Google got me Volker Kirchhoff as one of the people working on this. Vicki Rosenzweig
Moved the following pending source (I hope it's there, I believe you, Vicki!):
- Increased ultraviolet, presumably due to ozone depletion, has been measured in Toronto, Canada and in southern Chile.
If solid measurements exist, we should be able to find them this week. I'd be happy to see those measurements quoted and cited in the article.
Atmospheric scientist Fred Singer wrote (half a dozen years ago) that scientists had yet to see any increase of solar ultraviolet radiation at the Earth's surface. I'll wait a day or two and see if Vicki or anyone finds any more recent measurements before restoring the deleted text. Ed Poor
Okay, some quick Canadian references, with data from today (literally), 1993, and 1997:
- For current data, try http://woudc.ec.gc.ca/e/ozone/ozonecanada.htm
- "In 1993, the expected link between ozone depletion and increases in UV radiation at the surface was finally confirmed through the analysis of spectral data. The study, by Environment Canada scientists, has recently been extended to cover an 11-year period ending in 1996. It shows a positive trend of approximately 1% per year in the summer radiation at 300 nm." (From http://exp-studies.tor.ec.gc.ca/ozone/Summary97/Summary.htm, which also has a good color map comparing ozone levels over Canada in 1987 and 1997.) Vicki Rosenzweig
The web page you quote concedes that the scientific basis for the graph is "minimal":
- The accompanying graph shows how ozone has decreased from 1965 to 1996. It then compares, in a simplified fashion, what might happen if our current assumptions about ozone depletion are correct, and the Montreal Protocol and its amendments are fully implemented, with an alternative scenario in which concentrations of ozone-depleting substances remain unchanged at 1997 levels. Although the scientific basis for the graph is minimal, it does illustrate that evidence of a clear trend towards increasing ozone amounts may not emerge until after 2005 or 2010. In reality, however, such evidence may be delayed even further because compliance with the protocol may not be complete and there are still uncertainties in our understanding of the science. These uncertainties also make it difficult to predict confidently when ozone concentrations will finally return to natural levels. [1]
Also, the page mixes science with advocacy a lot. This makes it hard to read. While this doesn't disqualify it from being a wikipedia reference (i.e., I won't delete it), it's hardly satisfying to the interested layman.
I removed the following paragraph from the main page:
- In its report in June 1990, the UK Stratospheric Ozone Review Group concluded that there are serious limitations in our understanding and ability to quantify ozone depletion at the present levels of contaminant release and in our ability to predict the effects on stratospheric ozone of any further increases (SORG 1990).
I cannot make sense of this. What "further increases" are they talking about? And what does the "UV on biological systems" article have to do with anything? We are talking about ozone depletion. That reference could go into the UV article. AxelBoldt
Ed: In your overwhelming efforts to distinguish between NPOV and non-NPOV you seem to be taking a rather non-NPOV stance. For instance, "Some advocacy groups attribute a role to human-made substances" without explaining that these include scientists as well as conventional wisdom is no less non-NPOV than you think the statement: "Scientists attribute a role ..." is. Rather than upholding one position, you seem to be belittling another. Not a very NPOV thing to do. Danny