Arguments
CO2 lags temperature - what does it mean?
What the science says...
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CO2 didn't initiate warming from past ice ages but it did amplify the warming. In fact, about 90% of the global warming followed the CO2 increase. |
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Climate Myth...
CO2 lags temperature
"An article in Science magazine illustrated that a rise in carbon dioxide did not precede a rise in temperatures, but actually lagged behind temperature rises by 200 to 1000 years. A rise in carbon dioxide levels could not have caused a rise in temperature if it followed the temperature." (Joe Barton, US House of Representatives (Texas) 1985-2019) - Full Statement
At a glance
Antarctic ice-core data today provide a continuous record on temperature and atmospheric composition that goes back for some 800,000 years. The data track the last few glacial periods and their abrupt endings, with rapid transitions into mild interglacials. But in some of the ice-cores, temperature rises first and is followed, a few hundred years later, by rising carbon dioxide (CO2) levels.
Certain purveyors of climate-myths seized on this observation, claiming it to be “proof” that carbon dioxide doesn't cause climate change. Wrong, wrong, wrong. But how? The answer lies in a beer-can.
In fact, you can do this one yourself. You need two cans of any fizzy beer. On a nice summer's day, take one out of the fridge and place it outside in direct sunshine for a few hours. Leave the other where it is. Then open the two at the same time. The warm one will froth like mad, half-emptying the can and making a mess. What is left in the can will be horrible and flat. Conversely, the one straight from the fridge will just give a “pfft” noise and will be pleasant to drink, being cool and fizzy.
What's that got to do with this myth? Well, you have just demonstrated an important point about the solubility of CO2 in water. CO2 gives fizzy drinks their fizz and it is far more soluble in colder water. As the water warms, it cannot hold onto as much CO2 and it starts to degas. Hence that flat lager.
Exactly the same principle applies to the oceans. When global warming is initiated, both land and the oceans start to warm up. On land, permafrost starts to thaw out, over vast areas. Carbon dioxide (and methane) are released, having been trapped in that permafrost deep-freeze for thousands of years. At sea, that “warm beer effect” kicks in. Thanks to both processes, atmospheric CO2 levels rise in earnest, amplifying and maintaining the warmth. That rise in CO2 thereby caused more of the gas to be released, warming things up yet more in a vicious cycle, known as a positive feedback. Other feedbacks kick in too: for example as the ice-sheets shrink, their ability to reflect Solar energy back out to space likewise decreases, so that heat is instead absorbed by Earth’s surface.
The trigger for the initial warming at the end of an ice-age is a favourable combination of cyclic patterns in Earth's orbit around the Sun, leading to a significant increase in the solar energy received by Earth's Northern Hemisphere. That's no secret. Glacial-interglacial transitions are caused by several factors working in combination – triggers and feedbacks. We've understood that for a long time.
And when you think about it, saying CO2 lagged temperature during glacial-interglacial transitions so cannot possibly be causing modern warming is a bit like saying, “chickens do not lay eggs, because they have been observed to hatch from them".
Please use this form to provide feedback about this new "At a glance" section. Read a more technical version below or dig deeper via the tabs above!
Further details
That CO2 can lag behind but amplify temperature during a glacial-interglacial transition was in fact predicted as long ago as 1990. In the paper The Ice-Core Record: Climate Sensitivity and Future Greenhouse Warming by Claude Lorius and colleagues published in the journal Nature in 1990, a key passage reads:
"The discovery of significant changes in climate forcing linked with the composition of the atmosphere has led to the idea that changes in the CO2 and CH4 content have played a significant part in the glacial-interglacial climate changes by amplifying, together with the growth and decay of the Northern Hemisphere ice sheets, the relatively weak orbital forcing and by constituting a link between the Northern and Southern Hemisphere climates."
This was published over a decade before ice core records were accurate enough to confirm a CO2 lag. We now know that CO2 did not initiate the warming from past ice ages but it did amplify the warming. In fact, about 90% of the global warming followed the CO2 increase.
Antarctic ice cores reveal an interesting story, now going back for around 800,000 years. During this period, changes in CO2 levels tend to follow changes in temperatures by about 600 to 1000 years, as illustrated in Figure 1 below. This has led some to disingenuously claim that CO2 simply cannot be responsible for the current global warming. Unsurprisingly, such a claim does not tell the whole story.
Figure 1: Vostok ice core records for carbon dioxide concentration and temperature change.
The initial change in temperature as an ice-age comes to an end is triggered by cyclic changes in Earth’s orbit around the sun, affecting the amount of seasonal sunlight reaching Earth’s surface in the Northern Hemisphere. The cycles are lengthy: all of them take tens of thousands of years to complete.As both land and oceans start to warm up, they both release large amounts of CO2 into the atmosphere, from melting permafrost and from warming ocean water, since CO2 solubility in water is greater in cold conditions. That release enhances the greenhouse effect, amplifying the warming trend and leading to yet more CO2 being degassed. In other words, increasing CO2 levels become both the cause and effect of further warming. Once started, it’s a vicious, self-reinforcing cycle - an excellent example of what science refers to as a positive climate feedback.
Indeed, such positive feedbacks are necessary to complete the shifts from glacial to interglacial conditions, since the effect of orbital changes alone are too weak to fully drive such variations. Additional positive feedbacks which play an important role in this process include other greenhouse gases like methane - you may have seen videos of that gas bubbling up through icy lakes in permafrost country and being ignited. Changes in ice sheet cover and vegetation patterns determine the amount of Solar energy getting absorbed by Earth’s surface or being reflected back out to space: decrease an ice-sheet’s area and warming will thereby increase.
The detailed mechanisms for the above general pattern have of course been investigated. In a 2012 study, published in the journal Nature (Shakun et al. 2012), Jeremy Shakun and colleagues looked at global temperature changes at the commencement of the last glacial-interglacial transition. This work added a lot of vital detail to our understanding of the CO2-temperature change relationship. They found that:
1) The Earth's orbital cycles triggered warming in the Arctic approximately 19,000 years ago, causing large amounts of ice to melt, flooding the oceans with fresh water.
2) This influx of fresh water then disrupted ocean current circulation, in turn causing a seesawing of heat between the hemispheres.
3) The Southern Hemisphere and its oceans warmed first, starting about 18,000 years ago. As the Southern Ocean warms, the solubility of CO2 in water falls. This causes the oceans to give up more CO2, releasing it into the atmosphere.
4) Finally, CO2 levels may lag temperature in some ice-core records from Antarctica, but in some other parts of the world the reverse was the case: temperature and CO2 either rose in pace or temperature lagged CO2. Figure 2 demonstrates this graphically and shows how things are never as simplistic as purveyors of misinformation would wish.
Figure 2: Average global temperature (blue), Antarctic temperature (red), and atmospheric CO2 concentration (yellow dots). Source.
Last updated on 14 February 2023 by John Mason. View Archives
For a longer view of the correlation between CO2 concentrations and global temperatures, look no further than this reconstruction of the past 540 million years of such from Scotese (Scotese 2021 - Phanerozoic paleotemperatures: The earth’s changing climate during the last 540 million years):
Link to paper
Link to uploaded graphic
And leaving the last word on the subject to Scotese, a true expert in the field:
Thanks, MAR. I see that the story at The Conversation mentions one of the references linked in the Intermediate tab of this post (Parrenin et al, 2013).
Thanks Bob. I was just looking for something clearer. Don't really like the presentation on the intermediate and advanced tabs (forgot about those tabs, btw). Something with the lines closer together and the association clearer. With the lines colored and over each other. Thanks for your and other's efforts.
I did see one that made me gasp that blamed it somehow on jupiter and dust. Huh?
The analogy was cute, that the observation that CO2 rises lag temperature rises, means that the Temp rise causes the CO2 rise, is a bit like saying that chickens do not lay eggs because they have been observed to hatch from them. I would submit that, by the same token, opining that CO2 increases cause global warming is a bit like saying that chickens to not hatch from eggs, because they they’ve been observed to lay them.
This all suggests (as inferred) a co-dependent process.
However, this overlooks the same thing that MOST public blogs overlook, and that is the quantum mechanical mechanism on IR radiation (per greenhouse warming theory) has never been proven, and is actually false. New research indicates the fundamental error in the theory, presumes that Heat is ADDITIVE (eg. The Earth’s energy ‘budget’). The quantum process for Thermal transference is not additive. It is a function of frequency resonance. This is why microwave ovens work. Solar heating occurs because the spectrum of frequencies included in sunlight (which reaches the Earth’s surface) sets the maximum temperature which the recipient object may reach. An object in an oven set to 400 degrees will never reach 500 degrees no longer how long it is in the oven, because heat transference is not additive over time. The low energy IR waves received by CO2 molecules will naturally dissipate into the atmosphere with negligible net effect upon the atmosphere, but will never cause planetary ‘heating’ because, per thermodynamic law, no object can heat something beyond the temperature it possesses. Irradiated CO2 molecules can never heat the earth beyond the temperature frequency that already exists within the earth, which generated the IR light waves to begin with. IR Radiation does not raise the temperature of the Earth. The greenhouse warming theory is flawed. THAT is why the universally accepted historical record shows zero correlation between atmospheric CO2 levels and average temperature over the entirety of the past 4 Billion years. Zeroing in on the last 400k or 800k years, and pointing to an anomaly amounts to cherry picking, which disregards the other dynamics in play, such as Milankovitch Cycles. Note: Ozone depletion CAN increase surface temperatures because the range of UV frequencies that reach the surface is expanded.
RBurr @654 : Your ideas are interesting, to some extent.
But your ideas are based on semantics, not on physics. And sadly, the Greenhouse Effect cannot simply be talked away.
Education is the path forward for you. Good luck !
Ah, RBurr's comment at 654 is indeed an odd duck. While demanding "proof", he is badly short on providing any "proof" for his wild assertions. He alludes to "new research" (Where? By who? What publication?), but then just asserts a bunch of old misconceptions.
RBurr's assertions on "quantum mechanics" can be roughly lumped into a denial of the conservation of energy, a gross misunderstanding of the concept of temperature (individual molecules don't have temperature, and temperature is not a property of radiation), with a mix of "violates the second law" bunk.
There are other threads here at SkS where such topics can be discussed (and have been, at length).
A little learning is a dangerous thing;
drink deep, or taste not the Pierian spring:
there shallow draughts intoxicate the brain,
and drinking largely sobers us again.
RBurr @ 654
1) CO2 lags temperature rise at the end of an ice age because CO2 evolves from ocean waters as the temperature rises. This is Henry’s Law. In that case, temperature rises first due to the Milankovitch Cycles. Note that ice age temperatures cool slowly and warm rapidly. Modern CO2 emissions are different because they come from burning fossil fuels. Therefore, temperature rises as a result of CO2. Cause and effect in both cases is clear in both cases, and different in both cases.
2) The quantum mechanical mechanism on IR radiation that explains the greenhouse warming theory has been proven. It is based on fundamental principles of energy balance and radiant energy transfer and has been verified by massive amounts of data, cross-checks, and validation.
3) The Earth’s energy “balance” is fundamental:
Input = Output + Accumulation
Output is reduced as greenhouse gases increase. Thus, energy accumulates.
4) Your description of quantum mechanics does not make sense. Quantum mechanics is fundamental to the specific frequencies (i.e., wavelengths) that are absorbed and emitted by CO2, CH4, and H2O. There is a huge amount of energy carried by IR radiation. It is naturally emitted (not dissipated) and lost to outer space by IR. By the overall global energy balance at steady state:
Input solar = Reflected solar + Emitted IR
Accumulation is zero at steady state, as before CO2 emissions of the industrial revolution.
5) The hot object in this case is the sun at about 5800 Kelvin. That is more than hot enough to warm the earth. The temperature profile is 5800 K of the sun to 288 K (60F) of the Earth 217 K of the lower stratosphere to 2 K of outer space. Increasing CO2 reduces the energy loss to space at specific wavelengths (e.g., approx. 13-17 microns). The absorptance/emittance lines in that range increase, meaning that energy is emitted from a cold 217 K instead of a warm 288 K. This upsets the energy balance. The balance is restored by accumulating energy until the surface temperature increases enough to make up the reduction by CO2. Nothing about this violates either the 1st or 2nd law of thermodynamics. Some mistake the 2nd law by describing the energy balance being at steady state, but the steady state was upset by increasing GHG.
6) Neither the Milankovitch Cycles nor the Schwabe Cycles (sunspots) explain the cause of modern global warming. The long-term Milankovitch Cycles have not been in a period of significant change for the last 12,000 years after warming from the last ice age. Measured radiosity data from the sun show that short-term Schwabe Cycles have not changed significantly either and do not explain modern warming.
The mention of quantum mechanics warrants further discussion so one is not baffled or misled by a misrepresentation of it. Besides, the science is fascinating, and the concept is not that hard to understand. All molecules above absolute zero have internal energy. They vibrate, bend, and stretch in a limited number of ways that depend on their structure and ability to interact with electromagnetic radiation. Absorption and emittance of a photon changes the internal energy level by a discrete amount, which gives rise to discrete absorptance/emittance lines. CO2 is a linear, non-polar molecule that can stretch symmetrically and asymmetrically, but also polarizes temporarily when it bends. When molecules in the atmosphere have absorptance/emittance lines that fall within the wavelength range of IR at moderate temperatures by the Planck distribution, they become greenhouse gases. Discrete lines for CO2 and H2O are illustrated in Figure 3 in Introduction to an Atmospheric Radiation Model.
One more comment about the “quantum process” which is described incorrectly by RBurr @ 654. CO2 is “additive” and increasing. Thus, it is affecting the accumulation term in the global energy balance.
What an absolute joke of site this is. This isn't science, its a bunch of clowns that can't handle critisism and a hall monitor running around telling people what they can and can't say. Its no wonder that out of the dozens of comments I've read on this thresd, not ONE, gives a straight answer to the question that's at the heart of the entire theory of human driven climate change. You and those you parrot better be right.
[BL] If your goal is to get banned, so you can go and tell your friends that Skeptical Science is unwilling to listen to your wisdom, then you are off to a good start. You'll save us all a lot of time if you just post a comment saying "please ban me".
If your goal is to actually discuss any of the science, then you actually have to be willing to make a specific, supported, scientific statement that is related to the discussion topic of the original post, then you'll need to read and follow the Comments Policy. There is a link to the policy above the box you used to post your comment.
The first two statements of the Comments Policy are:
...but there are a couple more that you have violated in your brief rant. Surely someone of your great intellect will be able to read the policy and identify which rules you have broken.
Please note that posting comments here at SkS is a privilege, not a right. This privilege can be rescinded if the posting individual treats adherence to the Comments Policy as optional, rather than the mandatory condition of participating in this online forum.
Please take the time to review the policy and ensure future comments are in full compliance with it. Thanks for your understanding and compliance in this matter.
Wavefunction @659 :
Hmm. Now that you have vented your emotions
. . . perhaps you would be so kind as to make an On-Topic comment that is interesting and relevant.
Or try posting at the WattsUpWithThat blogsite, where about 80% of comments are venting & echo-chambering of non-science.
Wavefunction @659 raises an important point.
As a professional engineer with an MBA I have pursued developing a well justified understanding, open to being improved by justified criticism, of what is required to develop sustainable improvements.
Everyone should welcome and engage in learning based on ‘justified’ criticism of developed beliefs and justified criticism of poorly justified or unjustified criticism. That is how ‘scientific understanding improves’, including how this site’s content has constantly improved. It is also how businesses and political groups can learn to be more sustainable (less harmful and more helpful actions have more of a future).
The persistence, and in some cases the tragic growth or regrowth, of unjustified confidence in harmful misunderstandings is an undeniable problem. An aspect of that problem is the unjustified angry responses to sensible efforts to increase awareness and improve understanding that help people learn to be less harmful and more helpful members of humanity.
Correction of tragically popular misunderstandings, especially misunderstandings regarding harmful profitable activity (including excusing or denying harm done because of perceived benefits), is essential to the development of sustainable improvements for the benefit of all children now and into the distant future.
Learning about required corrections of thoughts and beliefs is also necessary for the successful repair of the damaging results of the popularity and profitability of ‘lack of awareness and misunderstandings’. Popular and profitable lack of awareness and misunderstanding can be very resistant to ‘justified criticism that would improve and correct it’.
I welcome justified criticism to improve that understanding.
[BL] I disagree that Wavefunction has raised any interesting points. He starts with an insult, continues with name-calling, and makes a wild claim that none of the "dozens of comments" he has read (on a topic that had 658 comments on it before he posted) "gives a straight answer" to some unspecified "question that's at the heart of the entire theory of human driven climate change".
The comment deserved to be deleted in its entirety, due to it's lack of anything specific, its tone, and its numerous violations of the policy - but it also deserves to be left up for anyone that reads it to see what Wavefunciton's behaviour is.
You have used Wavefunction's comment to make what are interesting and valid points. Reasonable discussion, justified criticism, avoiding angry unjustified response. All are worthwhile goals. The Comments Policy begins with:
The purpose of the discussion threads is to allow notification and correction of errors in the article, and to permit clarification of related points. Though we believe the only genuine debate on the science of global warming is that which occurs in the scientific literature, we welcome genuine discussion as both an aid to understanding and a means of correcting our inadvertent errors. To facilitate genuine discussion, we have a zero tolerance approach to trolling and sloganeering.
Genuine discussion requires a willingness to provide clear communications. Wavefunction hasn't even come close.
OnePlanet @661 : yes.
Now we await Wavefunction's first piece of "justified criticism".
Patience may be required ...
[BL], I agree. That is why I focused my reponse on wavefunction's unjustified criticism "...can't handle critisism [sic]...". To be honest, I had a faint hope that opening with the suggestion that wavefunction's comment raised an important point would get them to read my full comment.
Eclectic, I agree. Also, a lack of a justified response by wavefunction would indicate that they "can't handle, learn from or deliver, justified criticism".
[BL] Hope is a good thing....