Quote:I think you missed the point. You were nonspecific about Snowball Earth. So really what you implied, and what anyone would "get" from reading you, is that if CO2 was really that big of a deal then the planet wouldn't have frozen solid. Whether or not I would have worn shorts had I been around is irrelevant. But you can't utilize a theory for your purposes that also relies on CO2's known feedback effects to backup your point. That would be like a creationist trying to use microevolution to refute macroevolution. It's dead on arrival.
No, more generally the point is ANY and EVERY ice age in this period of time is a puzzle of you to explain. Because you believe the sensitivity to CO2 doubling in concentration is 3 degrees Celsius, you'd expect the Earth to be around 10 degrees warmer than today (around 25 degrees C) just based on CO2. So every severe glaciation -- or period that you wouldn't have wanted to wear shorts -- is a big question mark for you. It's not necessary for me to defend the position that the Earth completely froze over to make my point.
But I'm happy to discuss this issue, partly to clarify my position, but mainly because it's just an interesting subject. I'll start out by pointing out ... yet again ... that I consider it well established that the greenhouse effect of CO2 is about 1 degree Celsius. The difference between myself and pro-AGW climate scientist would be that a "warmer" basically believes the Earth's climate system works to amplify any small forcing by about a factor of 3 or more.
A key feedback in the climate system is the "albedo" of the earth. The albedo is a measure of reflectiveness of the Earth. If the albedo is very high, then it means solar radiation is bouncing off the planet without being absorbed and turned into heat -- a lower albedo means more solar energy is being absorbed by the planet, a higher albedo means less energy is absorbed. It's not easy to precisely measure the albedo of the Earth, but it's generally estimated at around 0.3 or 30% of solar radiation is just reflected away. The primary drivers of the albedo are clouds and ice.
So in the case of snowball earth, if we assume the Earth had completely frozen over, the albedo due to ice would be very high. In fact the albedo would have played a key role in getting to snowball earth apparently, as once the glaciation had passed the tropics, the albedo would have become so high that the global temperature would plummet due to the lack of solar radiation being absorbed as heat. In order to thaw out the planet then, it would have been necessary to thaw out the tropics. This could have been done by a period of high tectonic activity/volcanism releasing large amounts of greenhouse gases (including CO2) into the atmosphere, which had probably reached low concentrations due to the low temperature -- meaning the volcanic gases then had much more impact. As the ice melts and the albedo of the Earth drops, more solar radiation is absorbed, working as a positive feedback.
But WAIT -- I hear you are about to ask -- what is the difference between then and now? Wouldn't CO2 increase temperature, thus melting the ice, and amplifying the temperature increase? The big difference would be CLOUDS. Today, a big contributor to the albedo of the Earth is clouds, which would seem to INCREASE as temperature increases, thereby providing negative feedback. But on snowball earth, clouds wouldn't play much of a role, because a white cloud covering white ice doesn't reflect 2x as much energy, and due to the lack of water vapour in the atmosphere.
Quote:OK, let's be clear and go through the steps:
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4) The National Academy backs him up and mentions others who reach similar conclusions. They also validate proxy indicators.
5) theRomantic says that the hockey stick has been "debunked."
I leave it to the open-minded readers to draw their own conclusions here, but I will add that you, theRomantic, can't accuse me of appealing to authority because debunking implies someone (according to you) debunked the hockey stick. Ergo, an authority had to debunk it. And in fact, Science does not rely on logic but rather on EXPERIENCE. If others replicate results, then conclusions are on firm ground, etc...
Giving credit where credit was due, that was certainly an artful misdirection. If someone had just been reading the thread casually, they might totally believe I was the one who was appealing to authority and arguing against empiricism.
So just to make the record clear, I did not appeal to the authority of anyone. Nor does the definition of the word "debunk" imply the neccesity of any "authority" whatsoever -- this is just your strawman. I made a very specific point that the key rings -- a key temperature proxy used in these kind of reconstructions -- have a correlation closer to -1.0 than +1.0 with temperature since 1960. I mentioned that I think that raises the key question, of whether the tree rings are a good temperature proxy at all -- as you say, science is based on EXPERIENCE after all.
To that, your response was to appeal to the authority of the NAS. I asked you what exactly you thought the significance of the position of the NAS was on this issue, to which you gave the dubious response above, accusing me of appealing to authority.
So, since you didn't answer my question, and so I can be clear on this issue and not have to misrepresent your position as you have mine several times now -- what exactly do you think the significance of the position of the NAS is here, or on the subject of AGW more generally?
To that I'll just add, with regard to your statement that "Science does not rely on logic but rather on EXPERIENCE", how do you reconcile such a statement with the reality that while climate models -- which are based on logical models of how the climate works -- predict a temperature sensitivity of 3 degrees C per CO2 doubling, while we've only seen a 0.6 degree C rise as a result of 44% of a CO2 doubling (a rate of less than 1.4 degrees C)? And that we've also seen increased solar activity in this time frame?
Quote:You haven't made any. Your "points" are that whatever I use as a reference doesn't count. You also have no explanation for the warming. Now, if you'll cooley go through the data, show exactly how we're not warming, how Mann's math is wrong, why looking at ice core's ( and other kinds of sea samples) doesn't yield anything...then you might have points. As a laymen who is a fan of science and reason, I find your posts rather anti-scientific.
I don't blame you for imagining I haven't made any points, considering it seems you've barely even read any posts. After all, you're a Climate Fundamentalist, so you're not interested in reading any opposing views.
So, to give you the quick rundown, the temperature has risen by 0.6 degrees since 1880, which is not consistent with a 3+ degree increase due to global warming, Mann's work is addressed in part above (although's there's more!), and as for the ice cores, well I thought you'd never ask! The ice cores clearly show that there is a roughly a 800 year lag between temperature and CO2. That is to say, temperature increases/decreases FIRST, and then some time later, CO2 begins to increase/decrease as well, in general. This and the in general close relationship between temperature and CO2 is explained by a fairly simple property really -- the solubility of CO2 in water is lower as temperature increases. So when temperature increases, the oceans release CO2, and when they cool, they absorb CO2. Hence the close correlation.
Edited: Edited to remove ad hominim comment
~SF March 12, 2010