Three points.
1. Co2 has never been a driver, it has always been a FOLLOWER.
[ Professor Ian Clark ] So here we are looking at the Ice Core record from Vostok. And in the red we see temperature going up from early time to later time at a very key interval when we came out of a glaciation, and we see the temperature going up, and then we see the CO2 coming up. CO2 lags behind that increase. It's got an 800-year lag. So temperature is leading CO2 by 800 years.
[ Professor Nir Shaviv ] There were periods for example in Earth's history when we had three times as much CO2 as we have today, or periods when we had ten times as much CO2 as we have today. And if CO2 has a large effect on climate then you should see it in the temperature reconstruction.
[ Professor Ian Clark, Department of Earth Sciences, University of Ottawa ] If we look at climate through the geological timeframe, we would never suspect CO2 as a major climate driver.
[ Professor Syun-Ichi Akasofu, Director, International Arctic Research Centre ] CO2 began [to] increase exponentially in about 1940, but the temperature actually began to decrease 1940, continued till about 1975. So this is the opposite to the ration [reason]. When the CO2 increasing rapidly but yet the temperature decreasing we cannot say that CO2 and the temperature go together.
Faulty logic. That CO2 historically lagged temperature does not necessarily prove that CO2 cannot also cause temperature. Today, for instance, CO2 is most definitely not lagging temperature. It's following right along. CO2 is described as both a feedback and a forcing. The earth warms through some other mechanism, ice melts and released more CO2. The ocean also releases more CO2 when it gets warmer. (think like a soda bottle does) This is also true in the opposite direction: cooling temperatures will remove CO2 from the air. This is the feedback aspect: as you warm up and therefore increase CO2, that extra CO2 increases the greenhouse effect and further warms the planet. CO2 will amplify an existing temperature trend. However, this doesn't mean it can't also start a trend if you, say, spit gigatons of CO2 into the atmosphere every year by burning fossil fuels.
Here's the problem that you, and these prominent skeptics (i've read papers by all of them), are running into: Climate has multiple interdependent variables. If you look at the geological temperature record and compare it to solar activity, you'll also find no good correlation. The long-term trend of the sun (and I mean loooong term) is a gradual increase in output. (this is normal for a star of this type) So if the sun has been gradually increasing in output, why has temperature cycled up and down significantly? We're colder now than they dinosaurs would have seen, despite the higher solar activity today. One might conclude that solar output has no correlation to temperature. Obviously, this isn't the case. You can't look at just one variable and conclude there isn't a correlation. You could literally pick any variable and find no correlation if that's all you looked at.
For some more specifics:
1) Shaviv mentions historical CO2 being much higher. That's true. However, solar output was lower back then, the earth was in a different stage of its milankovitch cycle, and the continents were previously in different positions.
2) Clark's statement about not realizing CO2 was a factor can also be said about solar activity.
3) Akasofu's description of CO2 v Temp is a bit off.
The atmospheric concentration of CO2 didn't really shoot up until a bit after he describes. Also, there's that darn solar activity to account for. More than one variable! (see below!)
2. There is proof CO2 is not a driver. See above.
No, that's not proof. It's funny how skeptics will simultaneously say that climate is just so complicated that it's arrogant to assume we know anything for sure and simultaneously focus down on one variable and claim there's no link. I thought it was complicated, shouldn't you look at more than one variable?
3. There is a force, not unnatural, and known. The sun is a helluva driver. And is proven so. In fact one climatologst won a fair bit of cash betting on the sun to predict weather. Funny story:
[ Dr Piers Corbyn ] I decided to test it by gambling on the weather through William Hill against what the Met Office said was, you know, a normal expectation. And I won money month after month after month after month. Last Winter the Met Office said it could be or would be an exceptionally cold winter. We said no, that is nonsense. It's going to be very close to normal. And we specifically said when it would be cold, i.e. after Christmas and February. We were right. They were wrong.
[ Professor Eigil Friis-Christensen, Director, Danish National Space Centre ] When we saw this correlation between the temperature and solar activity, or sunspot cycle lengths, then people said to us, "OK, it could be just a coincidence", so [we thought] how can we prove that it's not just a coincidence ? Well one obvious thing is to have a longer time series, or a different time series. Then we went back in time.
So Professor Friis-Christensen and his colleagues examined 400 years of astronomical records, to compare sunspot activity against temperature variation. Once again they found that variations in solar activity were intimately linked to temperature variation on Earth. It was the Sun it seemed, not Carbon Dioxide or anything else that was driving changes in the climate.
This is great. You're quoting almost verbatim from
The Great Global Warming Swindle, which makes my rebuttal fairly easy! In that video, they showed you a chart that draws a link between the sun and temperature. Problem: They cut the chart off at 1980. I wonder why?
Oh. You see how after 1980 the solar output drops while temperature continues to increase rapidly? Why, if we're going with your own logic here, that must mean that the sun is not a driver of temperature! Clearly this is not the case. In fact, the trend of solar output has been completely flat since about 1950, yet the fastest increase in temperature occurs in this period.
Multiple. Interdependent. Variables. Seriously, people, this isn't hard! On a smaller scale like this, you need to look at CO2 as well as the 11-year solar cycle and El Nino/La Nina cycles, as well as some miscellaneous things like large volcanic eruptions that pop up every once and a while to throw a wrench into the whole business.
In a way it's not surprising. The Sun affects us directly of course, when it sends down its heat. But we now know that Sun also affects us indirectly through clouds. Clouds have a powerful cooling effect. But how are they formed ? In the early 20th Century scientists discovered that the Earth was constantly being bombarded by sub-atomic particles. These particles, which they called Cosmic Rays, originated, it was believed from exploding super-novae far beyond our Solar System. When the particles coming down meet water vapour rising up from the sea, they form water droplets and make clouds. But when the sun is more active and the Solar Wind is strong, fewer particles get through and fewer clouds are formed. Just how powerful this effect was became clear only recently when an astrophysicist Professor Nir Shaviv decided to compare his own record of cloud-forming Cosmic Rays with the temperature record created by a geologist, Professor Jan Veizer, going back 600 million years. What they found was that when Cosmic Rays went up the temperature went down. When Cosmic Rays went down the temperature went up.
Science.
In the werdz of the great Inspecteur Clouseau... case sull-ved.
.
Remember how I'd said I'd read papers by the guys you mentioned at the start? I've read the exact paper you're talking about, Shaviv 2003. Here it is!
http://www.juniata.edu/projects/oceans/GL111/celestialdriverofclimate.pdf
Here's the thing: Shaviv's work is on a multimillion year time scale. The idea is that the amount of cosmic energy we're exposed to changes as the earth
passes through the spiral arms of the galaxy. This simply does not happen on a century time scale. You have to move up into the millions of years. Even Shaviv admits this. He expresses a couple caveats in his paper:
Despite all these empirical observations and correlations, the solar-CRF-climate link is still missing a robust physical formulation. It is for this reason that such a link is often understated (IPCC, 2001),
Moreover, the inherent time scales required for the global climate system to reach equilibrium can be as large as several millennia, owing to the slow heat exchange between the oceans and the atmosphere, and to the slow ice sheet adjustment time. Thus, by estimating the effects of CO2 over geological time scales, we may obtain the long-term “equilibrium” response of the global climate system.
Shaviv (2002a, 2002b) proposed that a particularly large CRF variability should arise from passages of the solar system through the Milky Way’s spiral arms that harbor most of the star formation activity. Such passages recur at ~143 ± 10 m.y. intervals, similar to the 135 ± 9 m.y. recurrence of the paleoclimate data (Veizer et al., 2000). Unlike the extrinsic solar-induced CRF modulations, which change the ionization rate at the bottom of the troposphere by typically <10%, the galactic flux variations are much larger and are expected to be about an order of magnitude more effective. It is these intrinsic CRF variations that may be responsible
for the long-term climate changes over the past 1 Ga.
Specifically, the “icehouses” and the oxygen isotope cold intervals
Always. Read. The. Source.
Further complicating the matter, Shaviv's work banks on More Clouds = Cooler, as clouds will reflect sunlight back to space, cooling the earth. However, another prominent skeptic proposes precisely the opposite: That clouds trap in heat, therefore more clouds will keep the earth warmer.
Lindzen, 2001:
http://www.google.com/url?sa=t&sour...sg=AFQjCNFUM_cBm5xaoqCIkVQboQF3ObeGpw&cad=rja
Lindzen proposes that a warming world will have fewer tropical cirrus clouds, thereby allowing more infrared radiation to escape, this cooling the planet back down. Less clouds, colder planet, which runs contrary to Shaviv's less clouds, warmer planet theory.
Really, clouds do both. They reflect light in the visible spectrum, but also absorb light in the infrared spectrum. (Hence the H20 = greenhouse gas thing that skeptics ALSO like to point out) Yes, water vapor (clouds) can absorb that outgoing radiation and trap it, warming the planet. So the question does remain whether clouds introduce a warming or a cooling effect, and this is a subject of ongoing research.
