I’ve always figured the answer to the disappearing ozone layer was to load up cargo jets with Xerox machines, fly as high as possible, and run the copy machines with the loading ramp open. Don’t know how to get that long an extension cord, though.
I’m quoting from the US Inventory of Greenhouse Gases:
“Although CFCs and HCFCs include potent global warming gases, their net radiative focing effect on the atmosphere is reduced because they cause stratospheric ozone depletion, which is itself an important greenhouse gas in addition to shielding the Earth from harmful levels of ultraviolet radiation”
So yes, (some but not all) CFCs (and HCFCs) can act as greenhouse gases, but because they act to destroy ozone some of their global warming potential is negated. Furthermore, they are generally not considered in discussions of greenhouse gas mitigation because they have been controlled quite effectively by the Montreal Protocol. HFCs on the other hand (which replaced CFCs and HCFCs) are typically included in discussions because they are not covered by the Montreal Protocol.
I hope that clarifies that issue (and it certainly teaches me not to discuss this topic when I’m wound up and can’t think straight).
To see a wide variety of cites on climate change related articles you can check out http://www.climateark.org. Before discounting it as a site that asserts the validity of global warming remember that it is merely linking to articles published in major newspapers and quite often they are based on press releases from the likes of NASA and NOAA or on articles published in such places as Science, and Nature.
As for the CO2 causing plants to grow more–keep in mind that any increased growth (which is under study by the way and the results I’ve seen so far indicate that the correlation is not as simple as it would seem) would also be shared by harmful plants (eg–they’re predicting ragweed pollen season to start earlier, last longer and pollen count to increase). Besides, just because CO2 levels increase doesn’t mean that the other conditions will be right for increased plant growth (water, soil type, etc).
I wouldn’t go touting petitions as an example of how many scientists disagree with the theory of global warming. The original Leipzig declaration on climate change was supposedly signed by 100 people (actully about 80), of which about 20 were actually climate scientists, the remainder being from a variety of sceintific and non-scientific fields. See this link for more detailed info on that:
http://www.ozone.org/opposition/leipzig.html
Considering that over 2000 scientists collaborated on the IPCC reports I’d be more inclined to trust their findings.
I’m also hardly impressed by the signatures on the Seitz letter considering you can print out a form from the web and mail it it to have your name added. I couldn’t find anything on there website that indicated that they took the time to verify the claims of each signature they received.
There have been numerous reports that have indicated that global surface temperatures (and now water temperatures) have risen. They have even resolved some of the discrepancies regarding satellite data that was thought to contradict surface readings (see the story for 2/18/2000 on the climate ark site). I don’t know how to show you that temperatures have risen if you ignore the studies being published that show they have. (whether it’s anthropogenic or not and whether it’s a notable trend or not can be debated, but the fact that they have risen in our documented history is pretty clear).
Finally, TNTruth says that the enhanced effect has been predicted for 30 years but hasn’t happened–well, that’s because we’re talking about a massive, long term, phenomena that isn’t truly observable on human scales. Temperature differences of 1 degree or even 1/2 a degree may not be noticeable to you or me and may not sound like much but can have huge impacts on nature. A 1% increase in concentrations is minor now–but considering that our emissions keep going up every year (especially as nations like china and india continue to develop economically and use “dirty” technologies) and that the lifetimes of some of these gases are over 100 years it is likely to become more of an issue.
If all of this is so unsupportable, why are even the traditional holdouts on the issue beginning to change their positions? Numerous companies dropped out of the Global Climate Coalition, both the coal based utility companies I worked with in grad school had climate change programs, and even George Bush has sanctioned a study of Texas’s greenhouse gas emissions and charged the Board of Natural Resources with creating a greenhouse gas action plan.
I was looking at straight data for CFCs alone, not taking into account the net effect after ozone depletion. Gracias for the info.
on your second point…
I’ll have to check into it, but I have also heard that CFCs are a greenhouse gas (albeit a minor one) in addition to being an ozone depleter.
on the first point…
In the meantime, you have contaminated ground-level air around every airport in the world (which happen to be in major population centers…well, perhaps they won’t mind breathing metallic powder). And you’re messing up astronomy (my personal bugaboo). And that would be a major uncontrolled experiment with unknown long-term effects.
overall to the thread…
As I said before, I agree that human-caused global warming is still an unknown. But the greenhouse effect is a real phenomenon (which, as has been stated, naturally occurs to our benefit on Earth) (it occurs on other planets too like Venus). Even though there is current uncertainty, the potential hazards are high…so it makes sense, IMHO, to proceed with caution now, rather than to wait-and-see. Economically in the long-run, it would be cheaper to prevent it than to fix it. Unfortunately, short-term economics are a stronger motivating force.
Personally, I look to technology improvements and intelligent behavior to solve this problem…but both are hard to come by. Brute force legislation may be more effective (unfortunately).