This is an excellent response to the furious and unfounded assertions of the right-wing denialists that have followed from the release of private email by climate change scientists.
I’m on a couple of private mailing lists where we exchange views on evolution, and <shock horror> we actually argue it times, and sometimes even disagree heatedly with one another. That climate scientists hash out disagreements in vigorous private debate is no surprise, and no sign of either a conspiracy or intent to mislead the public.
@768: Arrhenius wrote a good paper on the subject in 1896, you should check it out. Then you can look for the paper that most directly establishes that the earth goes round the sun!
Stephen you’ve got me on the wrong side of the fence. I’m not a denialist. I accept CO2 is a greenhouse gas. But I’m looking for some papers to counter this quote by a someone trying to cast doubt on the science. Here is the quote:
“What you seem to be missing here is that all of our data of the historical PAST shows no cause-effect between temperature and CO2 concentrations. Actually, that is not true either… there is a strong correlation, but it is the other way around. In the past, temperature variations were followed about 800 years later by CO2 concentrations. All the evidence we had showed that temperature drove CO2, not the other way around.
So it is the idea that CO2 can cause temperature shifts that is actually the extraordinary claim, and the claim that goes against all PAST evidence.
Did you get that? The CO2 warming theory is the extraordinary claim. The claim that has to prove itself. Not the other way around.”
I’m trying to speculate why there would be a gap between a warm period and 800 to a thousand years afterward a surge in CO2 levels.
A period of warmth would lead to an increase in water evaporation would it not? This in turn would lead to more rain, which has CO2 dissolved in it. Which would lead to more rock erosion, which releases more calcium from those rocks.The dissolved CO2 reacts with the calcium from the eroded rocks, which would sooner or later reduce CO2. Less CO2 equals less erosion. Less erosion means less weathering, and CO2 builds up in the atmosphere again.
Is that a plausible rebuttal to the quote above?
@770: I was a little snarky but I genuinely do think you should look up the Arrhenius paper, you will find it wonderful ammunition.
The error in the argument you quote is simply this: the proposition that increased atmospheric CO2 leads to global warming is not a historical conclusion from climate reconstructions; it is a prediction based on the physical properties of the CO2 molecule. The fact that, historically, a warming of the earth can lead to subsequent CO2 increase (e.g. due to mobilisation of frozen carbon sources) is utterly unconnected to the current mechanism of warming. Engaging them with stuff about erosion is simply a distraction; they probably know that.
The situation is really quite simple. Earth is warmed by the light from the Sun, mostly in the visible spectrum. Earth cools by infra-red radiation. CO2 is transparent to visible light but absorbs infra-red light. Increasing the CO2 in the atmosphere reduces heat loss from the earth; so we get warmer. This is about as difficult or controversial as the proposition that if I drop this teacup off the roof, it will break when it hits the ground. Historically, I’ve never dropped this cup before- so what?
We’ve known about this mechanism for more than a century- hence the reference I gave. The guy claiming that CO2-induced warming is an extraordinary claim is, effectively, claiming that if I insulate my house and don’t turn down the heating, it’s extraordinary to claim that my house will get warmer!
Earlier in the thread I believe we had the wonderful analogy; billions of people have died in the past for all sorts of natural reasons; therefore you can’t possibly blame me and my smoking gun for this bullet-riddled corpse here.
Shadowjack, the 800-year lag is mentioned in the series of videos of which the one featured in the post is sixth.
Look at the part beginning in the sixth minute of the first video.
As has been explained several times on this thread, CO2 is a feedback on temperature. When Milanković cycles end an ice age, the extra heat from the sun thaws permafrost and warms the oceans, leading to outgassing of greenhouse gases (mostly CO2), which leads to more warming, and so on till a new equilibrium is reached.
This is why ice ages take so long – the change in insolation must be big enough to trigger the feedback – and why glacials and interglacials are so much of an either-or phenomenon instead of arbitrary points in a continuum.
This time around, however, the amount of greenhouse gases in the atmosphere is increasing for reasons other than temperature. That’s extremely rare in the Earth’s history. I think the last times were 55 million years ago, when something (changing sea currents?) apparently led to massive outgassing of methane from clathrates in the sea floor, and 67 to 63 million years ago, when the Seychelles broke off of India during a couple of flood basalt eruption episodes (CO2 comes out of volcanoes). Both of those times, the global annual average temperature rose considerably as a result.
This time it’s us. The temperature, and the sea level, have already started rising.
And the permafrost soils have started melting, giving off methane… the feedback is coming. Let’s hope it’ll be small this time.
The relevant real climate links on the lag between CO2 and temperature:
http://www.realclimate.org/index.php/archives/2004/12/co2-in-ice-cores
http://www.realclimate.org/index.php/archives/2007/04/the-lag-between-temp-and-co2/
http://www.realclimate.org/index.php/archives/2005/11/650000-years-of-greenhouse-gas-concentrations/
http://www.realclimate.org/index.php/archives/2007/12/hot-off-the-projector-3-atmospheric-co2-to-800-kyr-ago/
Shadowjack,
There aren’t really any peer-reviewed papers as such countering the “CO2-lags warming” meme, because it is precisely what you’d predict given the consensus theory of climate.
The CO2 has to come from somewhere, right? Well, if you have warming after an ice age (google Milankovitch cycles), eventually the permafrost starts to thaw and outgasses the CO2 that was trapped there. The released CO2 intensifies and prolongs the warming. In this case, the cause of the initial warming is increased insolation due to small changes in Earth’s orbit around the Sun, and CO2 is a feedback that causes more warming.
Like most denialist talking points, this one winds up being a bit of an own goal. Eventually, we will warm the planet sufficiently to release the CO2 now frozen in the tundra, and that will further intensify the warming, probably making it irremediable–Oops! What can I say, these guys are kinda stupid.
“Like most denialist talking points, this one winds up being a bit of an own goal. Eventually, we will warm the planet sufficiently to release the CO2 now frozen in the tundra, and that will further intensify the warming, probably making it irremediable–Oops! What can I say, these guys are kinda stupid.”
CO2 may not be the nastiest GHG but frozen under the tundra there is plenty of methane, which is nasty. Plus ocean warming may release methane clathrates further exacerbating global warming.
Thanks for your help everyone.
At least I won’t have to worry about refuting intelligently made points here. I have rarely heard such concentrated drivel in the overuse and constant pounding of strawman argumentation and logical fallacies.
The basis of any discussion is mutual respect ansd consideration. Good luck with that idea !
@opit: I can’t tell which side of this argument you’re attacking; the few comments above yours look pretty reasonable. Could you clarify?