A friend of mine has taken to ranting about the ozone layer. Not everything he says rings true, so I ask these questions:
[ul][li]Is there a hole in the ozone over the North Pole? Over the South Pole?[/li][li]Are the auroras borealis and australis caused by holes in the ozone?[/li][li]Do these holes shrink and grow over time? (Ie, he claims that they make grow 6 inches one year, and shrink 8 inches the next.)[/li][li]Is there any debate in the scientific community over whether humans contribute significant amounts of methane and carbon dioxide to the atmosphere? (Not whether this is harmful, but whether the amounts are significant.)[/li][li]Is this amount comparable to the amounts released in to the air by “natural” causes (ie, cows, volcanoes, whatever)?[/li][li]Is there proof that the amounts of these gases present in the atmosphere have increased significantly in recent years? If so, is this a normal part of the earth’s cycles?[/ul][/li]I am not looking for speculation or opinion so much as facts. Opinions can be debated forever, but I would like to present my friend with irrefutable facts.
As Mjollnir said it’s probably more informative to read one of the many books on this topic but here’s my take on it. Just a little disclaimer first: All figures are guesstimates, but probably adequately close.
It’s not a hole, but it is thinner there.
No. Auroras are caused by particles colliding with the atmosphere. The reason is mostly due to solar flares.
Yes, but inches are a tad conservative. The ozone layer is on average about 50km thick but can vary. I think the “hole” they found over antarctica in the 1980’s was a thinning of about 50%. Fluctuations are natural, but are increased by CFC’s and other gasses.
In the past 200 years, since man really began burning large amounts of fossil fuels, carbon dioxide levels have increased by 25%.
It’s not so much about the actual amount as it is about surplus. The earth can absorb a certain amount of CO2(plantlife) and releases a certain amount(animals). Naturally there are some fluctuations due to forest fires and so on, but over a larger time frame it’s stable. Under a short amount of time man has continuosly released a lot of CO2 that was “out of circulation” and stored in the ground as coal/oil. Since this surplus cannot absorbed, it stays in the atmosphere.
You friend’s really got you doing the research, huh? I have friends like that.
There are thinnings in the ozone layer in the polar regions. The ozone layer exists everywhere, but it has fewer total ozone molecules for the same volume over the poles.
No, they precede ozone depletion. Both auroras are essentially natural phenomenon - arctic atmospheres being caused to glow by particles blown out by the sun.
I don’t understand why anything atmospheric would be measured in inches. The ozone layer is roughly 60 km thick. The “hole” is simply a lower concentration of ozone in the layer it is supposed to found in great quantities. This deficit does vary over time though.
Not much. Most scientists recognize that a ton of greenhouse gasses are produced by humans (disagreement occurs over the extent of human-induced climate change, which is not the subject of your question). It should be noted that this is not an ozone-layer-specific problem. Check dis out: http://www.straightdope.com/classics/a4_176.html
Most of the worst ozone-depleters are purely man-made. They tend to propellants involving carbon-chlorine bonds; there are no carbon-chlorine bonds in nature. Other pollutant gasses - those not implicated in ozone depletion but probably responsible for other problems (acid precipitation, global climate change) have both human and natural sources (cows aren’t a natural source of methane, but there are comparable wild animals; lightning storms can create nitric acid rain, etc.) Humanity’s contribution to the problem varies from case to case.
Well, you’re in good company. Battalions of scientists spend a lot of time trying to figure this out. A lot of this stuff is simply too complex for humans to properly understand at this time. That’s part of the reason for some much public misunderstanding of this stuff.
The other part is willful misrepresentation by people on various sides. That’s why you shouldn’t rely on information from one side alone. Balance an anti-environmentalist like Dixy Lee Ray with work by environmentalists.
The other questions have been addressed to my satisfaction, here are some more thoughts:
<dl><dl>Is there any debate in the scientific community over whether humans contribute significant amounts of methane and carbon dioxide to the atmosphere? (Not whether this is harmful, but whether the amounts are significant.)
<dl>Is this amount comparable to the amounts released in to the air by “natural” causes (ie, cows, volcanoes, whatever)?
<dl>Is there proof that the amounts of these gases present in the atmosphere have increased significantly in recent years? If so, is this a normal part of the earth’s cycles?
<dd>For the ozone layer, carbon dioxide and methane are not important factors. Chlorine and related gases (CFC’s, etc.) are. Certainly humans have released more CO[sub]2[/sub] than the earth was ‘expecting’, but there is still a question as to whether natural processes release as much or more chlorine & related gases at times in earths history as humans have released due to refrigerators and hair spray.
Carbon Dioxide and methane may affect global warming, but it is not known for sure to what extent.
Sounds like you’ve got it straight to me. The real problem with humans causing ozone depletion is that the lifespan’s of chlorocarbon molecules is so freakishly long, thousands of years. So while natural chlorine spat out of a volcano would rain out or be otherwise removed from the ozone layer, artificial chlorine compounds stick around until doomsday.
Just out of curiousity, which side did you take and which did know-it-all friend take?
I didn’t really have a “side”, Boris, since I don’t know very much about this. I’d much rather try to find answers and then argue with him than to insist that he was wrong when I didn’t even know the facts.
To summarize his rant: There have been holes over the North and South poles since the beginning of time. The auroras (borealis and australis) are caused by these holes. In fact, that’s what the auroras ARE. These holes grow and shrink however many inches each year (and I don’t think he meant that the ozone thinned out, but that an actual hole was increasing/decreasing in diameter)The tree-hugging hippies throw a hissy fit every time the holes get bigger, but totally ignore the fact that they shrink again the next year. (The 6 inches and 8 inches example in the OP were his words exactly.) The CFCs and methane (no mention of CO2) released into the atmosphere by humans have no effect on the ozone whatsoever since the amounts are totally eclipsed by the amounts of methane released by cows and volcanoes.
Oh yes, a seven thousand-year-old redwood in California was knocked down by lightning. After examining the rings of the tree, scientists discovered that the recent changes (what changes? I’m not sure. I think he meant global warming.) were nothing new to this tree. It had seen it all before.
Oops! You went and dropped his name! Now I’m gonna tease every Carl I know and find out which one he is.
Actually, I’ve known a lot of people like your Carl. In fact, I’d be one myself, since I like to think a lot and discuss cockeyed theories I’ve made up. The only thing that saves me is my enjoyment of doing the research, and a good memory for the useless (and a correspondingly bad memory for stuff like what day it is sigh). One of my friends and I have arguments like this all the time - I’ve usually done my homework and he usually hasn’t. Recently he’s even started admitting I’m right sometimes.
I don’t want to make people think like me, I want them to think like me of their own free will.
God@#$%&! I didn’t realize that i’d done that. And we just had an argument about this thread (he thinks we’re all making fun of him for being wrong) where my big defense was “I didn’t even mention your name!”