Evidence for CO2 causing global warming?

[owtth]

from http://www.realclimate.org/index.php/ar ... p-and-co2/

“Doesn’t the relationship between CO2 and temperature in the ice core record show that temperature drives CO2, not the other way round?”

On the face of it, it sounds like a reasonable question. It is no surprise that it comes up because it is one of the most popular claims made by the global warming deniers. It got a particularly high profile airing a couple of weeks ago, when congressman Joe Barton brought it up to try to discredit Al Gore’s congressional testimony. Barton said:

In your movie, you display a timeline of temperature and compared to CO2 levels over a 600,000-year period as reconstructed from ice core samples. You indicate that this is conclusive proof of the link of increased CO2 emissions and global warming. A closer examination of these facts reveals something entirely different. I have an article from Science magazine which I will put into the record at the appropriate time that explains that historically, a rise in CO2 concentrations did not precede a rise in temperatures, but actually lagged temperature by 200 to 1,000 years. CO2 levels went up after the temperature rose. The temperature appears to drive CO2, not vice versa. On this point, Mr. Vice President, you’re not just off a little. You’re totally wrong.

Of course, those who’ve been paying attention will recognize that Gore is not wrong at all. This subject has been very well addressed in numerous places. Indeed, guest contributor Jeff Severinghaus addressed this in one of our very first RealClimate posts, way back in 2004. Still, the question does keep coming up, and Jeff recently received a letter asking about this. His exchange with the letter writer is reproduced in full at the end of this post. Below is my own take on the subject.

First of all, saying “historically” is misleading, because Barton is actually talking about CO2 changes on very long (glacial-interglacial) timescales. On historical timescales, CO2 has definitely led, not lagged, temperature. But in any case, it doesn’t really matter for the problem at hand (global warming). We know why CO2 is increasing now, and the direct radiative effects of CO2 on climate have been known for more than 100 years. In the absence of human intervention CO2 does rise and fall over time, due to exchanges of carbon among the biosphere, atmosphere, and ocean and, on the very longest timescales, the lithosphere (i.e. rocks, oil reservoirs, coal, carbonate rocks). The rates of those exchanges are now being completely overwhelmed by the rate at which we are extracting carbon from the latter set of reservoirs and converting it to atmospheric CO2. No discovery made with ice cores is going to change those basic facts.

[mistermack]

Why did you not say all that in the beginning?
Obvious denialist.
Case dismissed, no point debating.

Produce real evidence, it's what I asked for. The world is full of debaters. I thought SOMONE here would have some to show. I agree, no point in debating, if there isn't any.
And what the fuck is a "denialist" ?
.

[Tero]

last post, I am out of here

Another, quite independent way that we know that fossil fuel burning and land clearing specifically are responsible for the increase in CO2 in the last 150 years is through the measurement of carbon isotopes. Isotopes are simply different atoms with the same chemical behavior (isotope means “same type”) but with different masses. Carbon is composed of three different isotopes, 14C, 13C and 12C. 12C is the most common. 13C is about 1% of the total. 14C accounts for only about 1 in 1 trillion carbon atoms.

Furthermore, the 13C/12C ratios begin to decline dramatically just as the CO2 starts to increase — around 1850 AD. This is exactly what we expect if the increased CO2 is in fact due to fossil fuel burning.

http://www.realclimate.org/

You are not going to find the numbers for free on the net. They are published in copyrighted journals.

Denialists can be found in great gangs over here, enjoy
http://www.amazon.com/tag/science/forum ... tagsDetail

[mistermack]

Owwtf, what you just posted there actually repeats what I've said, especially if you read that article, and look at the reference to recent studies that have found exactly the same, and confirm an 800 year lag, with CO2 following temp.
The comment that it's the reverse over much longer periods still is ASTOUNDING, and betray huge bias.
We are being asked to accept that the present global warming has followed in LESS THAN FIFTY YEARS , the gradual rise in CO2 levels.
If that is correct, the graph of CO2 and temp should be practically photos of each other, with CO2 fifty years in front of temp, not 800 years after it.
.

[Robert_S]

Does CO2 keep more heat inside the atmosphere or does it not?

And what the fuck is a "denialist" ?
.

The word would imply that the person referenced would have turned the denial of something into a doctrine, or perhaps dogma.

Does CO2 prevent heat from leaving our atmosphere?

[owtth]

Owwtf, what you just posted there actually repeats what I've said, especially if you read that article, and look at the reference to recent studies that have found exactly the same, and confirm an 800 year lag, with CO2 following temp.
The comment that it's the reverse over much longer periods still is ASTOUNDING, and betray huge bias.
We are being asked to accept that the present global warming has followed in LESS THAN FIFTY YEARS , the gradual rise in CO2 levels.
If that is correct, the graph of CO2 and temp should be practically photos of each other, with CO2 fifty years in front of temp, not 800 years after it.
.

I believe you have that bassackwards.

[Eriku]

Owwtf, what you just posted there actually repeats what I've said, especially if you read that article, and look at the reference to recent studies that have found exactly the same, and confirm an 800 year lag, with CO2 following temp.
The comment that it's the reverse over much longer periods still is ASTOUNDING, and betray huge bias.
We are being asked to accept that the present global warming has followed in LESS THAN FIFTY YEARS , the gradual rise in CO2 levels.
If that is correct, the graph of CO2 and temp should be practically photos of each other, with CO2 fifty years in front of temp, not 800 years after it.
.

You don't think that for us to artifically cause a huge increase in the CO2 concentration would cause the mechanism to change somewhat? It CAN'T follow the temperature if we're injecting huge quantities into the atmosphere, throwing it off its regular cycle.

[mistermack]

last post, I am out of here

Another, quite independent way that we know that fossil fuel burning and land clearing specifically are responsible for the increase in CO2 in the last 150 years is through the measurement of carbon isotopes. Isotopes are simply different atoms with the same chemical behavior (isotope means “same type”) but with different masses. Carbon is composed of three different isotopes, 14C, 13C and 12C. 12C is the most common. 13C is about 1% of the total. 14C accounts for only about 1 in 1 trillion carbon atoms.

Furthermore, the 13C/12C ratios begin to decline dramatically just as the CO2 starts to increase — around 1850 AD. This is exactly what we expect if the increased CO2 is in fact due to fossil fuel burning.

http://www.realclimate.org/

You are not going to find the numbers for free on the net. They are published in copyrighted journals.

Denialists can be found in great gangs over here, enjoy
http://www.amazon.com/tag/science/forum ... tagsDetail

Tero, that's completely missing the point. You're not alone, everyone does the same. There is no disputing that human activity is putting CO2 into the atmosphere. The question is, is it having any effect on global temperatures? And I'm asking, is there evidence of that? You can't just point to more CO2, and say that it's caused higher temperatures. It never did in the past.
You can't just point to higher temperatures, that has happened over and over again, without any input from man.
None of this is evidence.
I started the thread to see if this is all there is, and it seems that it is.
Maybe there is more to come?
.

[mistermack]

Does CO2 keep more heat inside the atmosphere or does it not?

And what the fuck is a "denialist" ?
.

The word would imply that the person referenced would have turned the denial of something into a doctrine, or perhaps dogma.

Does CO2 prevent heat from leaving our atmosphere?

The theory is that it does. I accept that it acts as part of a natural greenhouse effect. However, nobody has shown how these gases work together. CO2 is a teeny tiny fraction of the atmosphere, and it's calculated contribution to that effect is also tiny. Water vapour is the biggy. More CO2 in the atmosphere could cause other effects that cancel out any effect it could have.
If you want to prove that more CO2 causes temperature to rise, surely that would be written absolutley clearly in the evidence of cores? Rises in CO2, followed within fifty years by rises in temp, just like we are being asked to believe?
??

[Feck]

[youtube]http://www.youtube.com/watch?v=S9ob9Wdb ... re=related[/youtube]

[mistermack]

You don't think that for us to artifically cause a huge increase in the CO2 concentration would cause the mechanism to change somewhat? It CAN'T follow the temperature if we're injecting huge quantities into the atmosphere, throwing it off its regular cycle.

You can look up the percentages of CO2 in the air. It's miniscule. And it's not that powerful anyway as a greenhouse gas. Water vapour has the biggest effect by far. And methane is far more powerfuls , but less abundant.
In any case, it's academic, because it's purely theoretical. The models that they are pushing can be made to show the exact opposite, just by making tiny changes to the parameters.
Basically, the models are showing exactly what people want to show, any that show the opposite are ignored or re-loaded. The ones that forcast warming are kept.
.

[beige]

There is no disputing that human activity is putting CO2 into the atmosphere. The question is, is it having any effect on global temperatures? And I'm asking, is there evidence of that? You can't just point to more CO2, and say that it's caused higher temperatures. It never did in the past.
You can't just point to higher temperatures, that has happened over and over again, without any input from man.
None of this is evidence.
I started the thread to see if this is all there is, and it seems that it is.
Maybe there is more to come?
.

I think the major issue here is the rate at which this change is occurring, and the fact that it's occurring well outside of the bounds of ordinary variation.

Can I ask where you got the impression from that CO2 has never in the past influenced global temperature? That seems to be completely at odds with anything I've ever read.

[Pappa]

mistermack, some of the comments you've made suggest you think that scientists are knowingly or unknowingly falsifying claims of dire consequences purely to stay on the science treadmill. Surely there would be as much cash in disproving climate change as there would be in proving it?

If you disagree with the last question there, I assume it's because you feel there is less funding for science that goes againt the current scientific consensus on climate change.

Could you elaborate a bit on the things I'm talking about?

[mistermack]

Feck, that film illustrates what I already knew, that David Attenborough is rather gullible and easily convinced. He has to be to be pushing that silly aquatic ape rubbish.
That guy showed no evidence, just a couple of models. They can and do get manipulated to show whatever you want. You simply ignore the ones that you don't like, and keep the ones you do.

And Beige, you only have to read up on the evidence. The ONLY link established between CO2 and warming, is that CO2 levels rise consistently, 800 years approx after a warm period. This is put down to warmer surface water in the oceans being circulated down to the depths, reducing eventually the ability of the ocean to store so much CO2.

If global temperatures rose and fell with CO2 levels within fifty years, we would see a nearly exact match for the temp and CO2 graphs, with CO2 levels leading the temp graph by about fifty years. That would HAVE to happen. It hasn't.
So the only actual EVIDENCE points to CO2 having no effect whatsoever on global temperatures.
.

[beige]

And Beige, you only have to read up on the evidence. The ONLY link established between CO2 and warming, is that CO2 levels rise consistently, 800 years approx after a warm period. This is put down to warmer surface water in the oceans being circulated down to the depths, reducing eventually the ability of the ocean to store so much CO2.
.

As far as I know, that applies to Ice Ages, ice ages are a different kettle of fish, because the warming after those is triggered by orbital shifts, not carbon dioxide. It's a different mechanism entirely to the current warming.