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Post by speakertoanimals on Jun 16, 2011 13:17:20 GMT 1
You miss my point -- I wasn't yet getting into the details of HOW much CO2 causes how much warming, I was just pointing out that the ability of CO2 to effect temperature AT ALL (which some people seem to doubt), rests on the effects of CO2 during earlier glacial periods. IF it could provide a warming effect then, it is LOGICALLY possible that it could do so now, without solar forcing, when introduced by some other source.
As regards much more CO2 in the past -- that's just the usual oft-repeated gunk that you can find answered on any decent FAQ -- that climate is determined by more than just CO2 levels! So, go back 400 million years or so, CO2 very high, but solar activity LESS. not quite so far back, and CO2 was higher, but SO WAS THE TEMPERATURE!
BUt that doesn't mean that incresing CO2 levels won't have an effect now, where other things AREN'T changing significantly, but CO2 IS.
As I keep saying, solar activity, positions of continents, ocean circulation, glaciation, CO2 all contribute towards explaining climate variation when we look back, be it 500 million, or 15 million years. And it all fits with CO2 and the greenhouse effect.
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Post by marchesarosa on Jun 16, 2011 13:24:48 GMT 1
So how could CO2 comprise an estimated 30% of the atmosphere during an early ice age? Is this consistent with CO2 causing runaway warming?
CO2 has been all over the place in the past and so have temperatures. Live with it. There is not a unique causal connection.
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Post by speakertoanimals on Jun 16, 2011 14:59:44 GMT 1
It is since it would have been a bloody lot colder WITHOUT those levels of CO2! Where did you get the figure of a third from? (Why do sceptics never give you PROPER references, just anecdotes?). 500 MYA, I think we had about 6000-7000 ppm for CO2. Plus 4% lower solar constant. You can find it all in the papers: droyer.web.wesleyan.edu/PhanCO2%28GCA%29.pdfHow many times are you going to repeat the SAME strawman argument? TO be precise, it's just the ole CO2 was MUCH higher in the past, and it was cold(er), therefore AGW is all pants............ Which will we get next? Nope, I still can find any records of CO2 levels of 30%, just 6000-7000 ppm 500 MYA (lower solar constant), and the late Ordovician stuff (440MYA?). Even with snowball earth scenarios, CO2 levels to cause breakout, although estimated as being 350 times more than today, still only 13% of total atmosphere.............................
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Post by buckleymanor1 on Jun 16, 2011 15:41:16 GMT 1
Mars 95% Co2 temperature-63oC Venus 96% Co2 temperature 467oC. Looks like an unlikely case of the tail wagging the dog. Must be the 1% increase on Venus that creates the warmer temprature and nothing to do with orbital variations.
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Post by speakertoanimals on Jun 16, 2011 15:51:54 GMT 1
Uh, what nonsense!
Mars may be 95% CO2, but the atmosphere (unlike Venus) is pretty damn thin and dry! Plus was further from the sun last time I looked!
Venus, closer to the sun, and atmosphere much thicker than on earth.
Just puklling figure out like this is total nonsense, because of course the question is :
1) compare like with like, no one said that temp only depended on percentage of CO2.
2) Meaningless unless you compute what the temperature of either planet would be WITHOUT any atmosphere in the first place!
So, saying oooh, only 1% difference, how WEIRD, just makes you look even denser than you probably are.
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Post by buckleymanor1 on Jun 16, 2011 16:03:11 GMT 1
That was the main point the distance from the Sun has more effect and the planets orbits than any levells of Co2.
Sorry from your previouse posts you seem to me to be giving the impression that it was the main driver in all temperature variations.
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Post by speakertoanimals on Jun 16, 2011 16:21:24 GMT 1
No, you can't conclude that either unless you know how hot Venus would be without an atmosphere. Explanation is that CO2 greenhouse effect is what makes it that hot -- hotter than Mercury, even though Mercury is closer.
Hence just straightforward comparison of Mercury and Venus shows you what the greenhouse effect can do -- Mercury with 427 maximum, Venus toasty 467, despite being about twice as far from the sun as Mercury (hence a QUARTER of the sunlight!).
Explain THAT without using the greenhouse effect (answers on a postcard please, addressed to NASA.).
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Post by marchesarosa on Jun 16, 2011 17:34:56 GMT 1
I wish people would not try to discuss other planets when we know so little about our own.
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Post by speakertoanimals on Jun 16, 2011 19:07:21 GMT 1
I'm sorry! WHAT was that for? We KNOW the atmospheric compositions of Venus and Mars, we know how far they are from the sun, hence if we can EXPLAIN what's earth temperature does, we ought to be able to explain what Venus and Mars do as well. In fact, if we didn't, I'd bet you'd be the first to say -- ah! but you can't explain why Mars is cold, and Venus is warm , hence your theory is wrong!
I notice that you have FAILED to answer the question as to WHEN the CO2 content of earths atmosphere was supposed to be 30%?
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Post by nickrr on Jun 16, 2011 20:36:56 GMT 1
Of course we'll live with it. However, if the temperature rises significantly changing weather patterns and rising sea levels will mean that "living with it" will become difficult and expensive.
However it's future generations who will have to do the suffering so you can continue to ignore it.
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Post by buckleymanor1 on Jun 17, 2011 0:47:23 GMT 1
Rotational period of Mercury more frequent than Venus.
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Post by marchesarosa on Jun 17, 2011 8:51:25 GMT 1
Mea culpa re CO2 being 30% of the atmosphere, STA. Memory playing up. What I was confusing it with was the description of limestone and Dolomite being comprised of 40% CO2 sequestered from the atmosphere.
And, yes, the CO2 levels in the pre-Cambrian were, apparently, up to 7000 ppm which is about 18 times higher than today. While rocks were sequestering huge quantities of CO2 the world was going through massive fluctuations in ice-sheet cover with glaciation alongside MUCH warmer oceans which facilitated the laying down of tillite by evaporation - all this due, it is claimed, to alterations in obliquity and huge seasonal variation.
I'm afraid I cannot discuss this with you further because I don't have the background however it looks to me as if CO2, whilst present in much higher concentration than today, was not the driver of these massive temperature changes and ice-sheet fluctuations - and neither is it today, in all probability!
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Post by marchesarosa on Jun 17, 2011 8:55:19 GMT 1
We do not, I believe, need to refer back to the Pre-Cambrian, however, to account for the trivial changes being experienced today in either CO2 or temperature.
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Post by nickrr on Jun 17, 2011 12:14:45 GMT 1
You are still missing the point. It doesn't matter whether CO2 was the driver in the past or not. Current research shows that it is the driver now and that's all that matters.
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Post by marchesarosa on Jun 17, 2011 12:19:07 GMT 1
"Current research", as you call it, nickrr, is based totally on modelling and predictions which are crap.
Remember basic stats 101 - correlation is not causation.
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