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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.

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

Earth’s climate has varied widely over its history, from ice ages characterised by large ice sheets covering many land areas, to warm periods with no ice at the poles. Several factors have affected past climate change, including solar variability, volcanic activity and changes in the composition of the atmosphere. Data from Antarctic ice cores reveals an interesting story for the past 400,000 years. During this period, CO2 and temperatures are closely correlated, which means they rise and fall together. However, based on Antarctic ice core data, changes in CO2 follow changes in temperatures by about 600 to 1000 years, as illustrated in Figure 1 below. This has led some to conclude that CO2 simply cannot be responsible for current global warming.

Figure 1: Vostok ice core records for carbon dioxide concentration and temperature change.

This statement does not tell the whole story. The initial changes in temperature during this period are explained by changes in the Earth’s orbit around the sun, which affects the amount of seasonal sunlight reaching the Earth’s surface. In the case of warming, the lag between temperature and CO2 is explained as follows: as ocean temperatures rise, oceans release CO2 into the atmosphere. In turn, this release amplifies the warming trend, leading to yet more CO2 being released. In other words, increasing CO2 levels become both the cause and effect of further warming. This positive feedback is necessary to trigger the shifts between glacials and interglacials as the effect of orbital changes is too weak to cause such variation. Additional positive feedbacks which play an important role in this process include other greenhouse gases, and changes in ice sheet cover and vegetation patterns.

A 2012 study by Shakun et al. looked at temperature changes 20,000 years ago (the last glacial-interglacial transition) from around the world and added more detail to our understanding of the CO2-temperature change relationship.  They found that:

  • 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. 
  • This influx of fresh water then disrupted ocean current circulation, in turn causing a seesawing of heat between the hemispheres.
  • 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.

While the orbital cycles triggered the initial warming, overall, more than 90% of the glacial-interglacial warming occurred after that atmospheric CO2 increase (Figure 2).

Shakun Fig 2a 

Figure 2: Average global temperature (blue), Antarctic temperature (red), and atmospheric CO2 concentration (yellow dots).  Source.

Last updated on 21 April 2021 by eckahle. View Archives

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Further reading

That CO2 lags and amplifies temperature was actually predicted in 1990 in a paper The ice-core record: climate sensitivity and future greenhouse warming by Claude Lorius (co-authored by James Hansen):

"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"

The paper also notes that orbital changes are one initial cause for ice ages. This was published over a decade before ice core records were accurate enough to confirm a CO2 lag (thanks to John Mashey for the tip).

Also, gotta love this quote from Deltoid in answer to the CO2 lag argument: See also my forthcoming paper: "Chickens do not lay eggs, because they have been observed to hatch from them".

Further viewing

Myth Deconstruction

Related resource: Myth Deconstruction as animated GIF

MD Lag

Please check the related blog post for background information about this graphics resource.

Comments

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Comments 451 to 475 out of 641:

  1. davytw @447, you have three excellent responses so far.  Let me add that it is often worthwhile taking denier cherry picks or other selective data at face value.  If you do in this case, for example, you see that the lag shown is about 1 year.  So, assume CO2 lags temperature by one year, and assume also, as per denier dogma, that there has been a pause in global temperatures.  It follows that from one year after the pause started (1995 and 1998 seem to be the preffered values) there has been a pause in the rise of global CO2 concentrations.  If your interlocuter cannot show you that pause the raw CO2 data, then it follows that either:

    There has been no pause in global temperatures; or

    CO2 does not simply lag global temperatures and the graph has been deceptively constructed to show an appearance that is not real; or both.

    In other words, even at face value combined with the raw data, the claim refutes itself.

    On a more subtle point, the partition of CO2 between the three main surface reservoirs (atmosphere, ocean and terrestial biosphere) is governed by temperature.  In particular, increased temperatures will shift CO2 from the ocean to the atmosphere.  If there are no other relevant factors, this is the primary short and medium term controller of CO2 concentration, and given the size of the effect relative to the increase in global temperature, dominates CO2 concentrations at sub decadal time scales.  However, anthropogenic emissions over a decade or more far exceed the variation in CO2 concentration caused by small temperature effects so that anthropogenic emissions control almost completely the long term rise.

    Long term temperture trends (such as occur at the start and end of glacials) can result in long term changes in CO2 concentration.  However, taking the graph your denier interlocuter provided, the ratio appears to be 1 ppmv of CO2 increase for every 2.5 C increase in temperature.  (Again the advantage of face value.  Your interlocuter must either admit that figure or something very close, or admit the graph has been deceptively constructed.)  Based on that figure, the approximate 1 C temperture increase since the preindustrial can only be responsible for about 0.5 ppmv increase on CO2 concentration ;)

    Of course that figure is way to low, because the graph is deceptively constructed.  Using the ratio between temperature and CO2 concentrations in the glacial, the actual increase in CO2 due to the 1 C increase in temperature may be as much as 20 ppmv.  Of course, that increase is itself no more natural than the warming.

  2. davytw @447.

    I have to say that your denialist has a pretty poor graph. There is a far better one, also from Wood-for-trees, up-thread @391.

    As folk here describe, there is a tiny CO2 effect due to rising global temperature but also due to ENSO which wobbles temperature & CO2 both, small (or perhaps more correctly very small) effects when compared with the direct anthropogenic inputs of CO2.

    These tiny wobbles are used by some, with added smoke and mirrors, to 'demonstrate' that rising CO2 is natural. I think Murray Salby takes the saddo prize in these works of lunacy as he has actually managed to line all his mirrors up to link this modern-day lagging of CO2 with the measured lags in CO2 in the ice core data. (If you can cope with such madness, there is a 68 minute video of his presentation here. I think it helps if you wear tin-foil hat, just to get into the spirit of the thing.)

    Encountering such mind-blowing nonsense once too often prompted me to produce this graphic (usuallt 2 clicks t 'download you attachment'). I forget whose equasion it was, possibly Humlum's. And I'm pretty certain there is a SkS version as well, somewhere.

  3. This one is isn't specifically related to "lags temperature", but it's another "CO2 / temperature - no correlation" graph, ostensibly from Doctor Richard Alley, showing the past 11,000 years from Greenhouse ice core data.  

    LINK

    My knowledge-free guess" effects from the sun are in the driver's seat here... am I somewhat right on that?  The "discussion" as it were is happening here:

    How to Talk to a Climate Change Denier

    Response:

    [RH] shortened link.

  4. Well anything from climate4you is likely.misinformation. This is discussed here and here.

    You might like to put "humlum" into the search box to see other stuff.

  5. :

    And here is the CO2 reconstruction we should be using:

    The immediate thing to notice is that the CO2 rises by 20 ppmv from 260 ppmv, leading to an expected temperature increase of 0.3 C.  Instead we get a temperature decrease of about the same amount.  Why?

    Well, here is the temperatures over the last 800,000 years:

    You will notice that after each large peak, the temperatures plummet rapidly, as we would expect with the rapidly declining NH summer insolation (which drives the timing of glacials).  There is one exception, that doesn't fall rapidly, that that is the last 10 thousand years.

    It is a natural supposition that the rise in CO2 levels (itself something we would not expect naturally) has counteracted the natural fall in temperatures we would expect from the declining NH summer insolation and greatly reduced the natural decline in temperatures.

    There is a recent post discussing just this topic. 

  6. Has this study been debunked on any other thread?

    http://file.scirp.org/Html/4-4700320_51443.htm

  7. It looks to me like these authors have been trying to promote this strange idea of adiabatic causes for warming for a long time, and have been repeatedly debunked. 

    http://wah-realitycheck.blogspot.com/2008/09/khilyuk-and-chilingar.html

    They even make the completely bizarre claim that increased methane concentrations would result in greater cooling. It's rather loopy stuff they're promoting.

  8. Quick

    From the introduction to the paper, discussing what they claim the standard model of the GH effect says -  "In particular, it assumes that the heat transfer in atmosphere occurs exclusively by radiation."

    Megafail right there.

    All the climate models include the basic physics that most heat transfer within the lower atmosphere is through conduction and evapotranspiration.

    What radiative exchange controls is the external energy balance with space. Ultimately setting the balance temperature for the mid troposphere at around 5 km up. The lapse rate then propogates  a temperature profile from that down to the surface.

  9. I haven't read the whole thing and only perused for a preliminary inspection. The paper has all the hallmarks of pseudo-science. The journal is definitely low impact. It does, however, details its review process, accessible through a few links. The list of citations of the paper includes ridiculous stuff like the Landscheidt piece in E&E, as well as the Robinson and Soon thing and an Soon/Baliunas/Robinson piece. The authors cite themselves on multiple occasions, several of these cites are books instead of peer-reviewed papers. In light of all this, I'm sure many will decide there are better uses for their time than reading and analyzing the piece to then explain where it goes wrong.

  10. Quick @456, the first thing to note is that the article is published by Scientific Research Publishing, number 405 on Jeffrey Beal's list of Predatory Publishers.  That means that despite the appearance the publisher attempts to give, the article is not in fact peer reviewed.  Rather, the article was published on the basis of a very careful peer review of money recieved from the authors to pay for posting it on an internet site (there is no associated print version).

    Turning to the paper itself, the core of the paper is found in their equation 2.  For the simplest rebutal, it is only necessary to note that the first term on the right hand side of the equation is bα, where "b is the scaling factor determined by the planet’s given surface temperature Ts in degrees Kelvin (for Earth Ts = 288.2 K)".

    In simple terms, that means that their equation does not determine the Global Mean Surface Temperature (GMST).  Rather, it requires an arbitrary value to inflate the temperature to whatever value that happens to be.  Indeed, as b is arbitrary, raising it to the power of alpha is a needless complication, and simply represent camouflage for the arbitrary nature of the term.  Further, as b > 1 for Earth, and >> 1 for Venus, that makes it plain that without this fudge factor, solar radiation plus pressure underpredicts the GMST.  Consequently, despite this being purportedly a refutation of the greenhouse effect, they need a greenhouse effect to make their theory work.

    The actual value of their fudge factor is 1.093 raised to the power of (γ-1)/γ, where γ is cp/cv, ie, the heat capacity under constant pressure divided by the heat capacity under constant volume.  In air, on Earth, cp/cv = 1.4.  Therefore, b is raised to the power of (approx) 0.286, so that the combined fudge factor is approximately 1.026.  

    Clearly that is not enough to account for the greenhouse effect, so they introduce the Earth's angle of precession,ψ, into the denominator of their middle term in a rather complex equation, reducing the denominator by a factor of 0.88, according to their claim (I have not done the maths).  Introducing this factor represents, in effect, a claim that tilting an effectively spherical body will increase the amount of sunlight it will intercept by 13.6%.  It might be supposed that their is some justification for this in that the Earth is an oblate spheroid - but it is simply not that oblate.  More importantly, they include no equation for the oblateness of the sphere in the equation, thus treating all planetary objects as having the same, very large oblateness.  As the introduction of the angle of precession cannot be justified in terms of the actual oblateness of the Earth, it is consequently just another fudge factor to account surreptitously for the greenhouse effect.  This fudge factor raises the zero greenhouse effect value for GMST from 255.8 K to 264.1 K, or an inflation by a factor of 1.03.  Including the first fudge factor raises the non-greenhouse GMST according to their model to 271 K.  That is, they predict a GMST 17 K below the actual value.  Despite this, in their figure 2 they show the surface temperature at 288 K, which strongly suggest their line in that graph was not calculated using equation 2, contrary to their claim.

    You may think I am ignoring the bulk of the paper in this critique.  The rest of the paper, however, simply plugs values into equation 2.  That is, it assumes there is not greenhouse effect to prove that CO2 has no significant effect on planetary atmospheres.

    I do agree with one decision by the authors of this paper.  If I had such a dogs breakfast as this paper, I would certainly not submit it to a proper journal for peer review either.  But neither would I submit it to the vanity press, for this paper can only deflate the reputations of its authors - however useful it may be as propaganda.

  11. @Rob, Glen, Philippe, and Tom.

    Thank you, gentlemen! My physics is a bit rusty, so at cursory glance this paper seemed to have some meat, but alas, my instincts prove correct. I knew some of you would have the proper resources readily available. Time to go educate 2 persistent skeptics. Thanks again!

  12. What do you guys make of this? The guy who posted it is trying to promote himself as a rogue genius or something.

    "First off they claim that CO2 is causing warming by absorbing infrared. They say it's preventing infrared that's in the infrared window range from being radiated away. But CO2 only absorbs 2 wavelengths of IR in that range. One peak at 9.4 microns and the other at 10.4 microns. Both peaks have absorption coefficients just less than 1%. Wien's displacement law shows temperatures radiating those wavelengths to be 95.25 deg F and 41.9 deg F. So it doesn't exactly involve much energy. Not only that, but one of those is BELOW mean global temperatures. Basically, they're trying to claim that a heater that only gets up to 95 deg F and radiates at 1% efficiency is warming the planet. LOL Hardly.

    The next thing they claim is that CO2 "absorbs" and then "re-emits" photons of IR coming from the surface, and THAT action "traps" heat by sending some of those IR photons heading back towards the surface. What they're desperately trying to describe is something called Stokes-Raman scattering, which is a type of inelastic scattering. Unfortunately for the AGW cult, there are only 2 wavelengths that get scattered by CO2, one at 7.20 microns and another at 7.78 microns. NEITHER of which are in the infrared window range. So that process doesn't stop ANY infrared from being radiated away.

    It gets even more interesting when you know how the process works. It works like this: A photon of 7.49 microns interacts with a photon that's ALREADY vibrating at the correct temperature (kinetic energy) as the photon. The photon gives up a bit of energy to the molecule which causes the molecule to now have a rovibrational component rather that just a vibrational component and the photon is scattered away at a lower energy level; now at 7.78 microns. This is called the Stokes shift.

    The next photon that's at 7.49 microns that interacts with that molecule will now absorb just a bit of energy (from the new rotational component) and will be scattered away at a slightly higher energy level; now at 7.20 microns. This is called the anti-Stokes shift. The molecule will then lose some energy, will stop rotating, and will drop back down to its original vibrational mode.

    The really emotional...err...I mean bizarre thing is, 7.49 microns isn't coming from the ground. The ground radiates between 8 and 14 microns. So 7.49 microns is INCOMING infrared. So the process is actually scattering some INCOMING infrared back out. The claim that it's scattering IR coming from the ground is a BIG LIE.

    I also said that the molecule must ALREADY be at the temperature (kinetic energy) of the photon. The temperature needed to scatter a photon that's at 7.49 microns is 236.76 deg F. On a hot day, only about 1 in 10 million CO2 molecules would be at that precise temp. On a cold day, even less. Perhaps 1 in every 30 million CO2 molecules."

    Response:

    [JH] Exactly where was this posted? 

    We want to check this out because recently we've had a spate of commenters who are attempting to disguise why they are posting denier memes on our comment threads.

  13. Did the guy cite any sources for his claims about absorption/emission spectra?

  14. I have responded in a more appropriate thread here. Please do not have any further responses to Quick on this thread.  Quick's issue is not about CO2 lagging temperature.

  15. JH, He posted as "Jim in CA" here: http://news.yahoo.com/emotions-not-science-rule-u-climate-change-debate-184843028.html?bcmt=1423418737492-0c1201c8-469f-4767-b168-0d3f364b5729_00023b000000000000000000000000-e9d055cf-f4cc-497d-9308-4e539fc56968&bcmt_s=u#mediacommentsugc_container

    Response:

    [JH] Thanks.

  16. Sorry..;link didn't work. It was in the comments of a yahoo repost of this Reuters peice: http://www.reuters.com/article/2015/02/05/us-climatechange-science-politics-idUSKBN0L92IN20150205

    Response:

    [PS] Fixed link

  17. Above you state: "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."

    How does this jibe with the ocean acidification narrative which postulates that in a warmer world with a higher CO2 atmosphere the ocean will absorb more CO2 and become acidic?

    Response:

    [DB] Your question on ocean acidification is dealt with in the 18-part 'OA is NOT OK' series, written by subject matter experts in that field, as summarized in Parts 1:

    http://www.skepticalscience.com/Mackie_OA_not_OK_part_19.html

    And Part 2:

    http://www.skepticalscience.com/Mackie_OA_not_OK_part_20.html

    If you have questions, place them on the appropriate thread and the subject matter experts will respond to them.

    [PS] Its about equilibrium - outgassing from warm ocean is something for centuries in future. The above links give the details.

  18. Patrick,

    You ask about how during the ice ages the ocean could outgas CO2 while warming but now it is absorbing CO2 while the temperature increases.  You can calculate the solubility of CO2 using the formula here if you want more accuracy.   

    The issue here is that on the "skeptical" blogs they do not consider the magnitude of processes.  They presume that any effect that seems to minimize the AGW problem is the dominate one.

    According to figure 1 in the OP, the CO2 changes from about 190 ppm to about 280 ppm during an ice age.  This is a change of about 90 ppm.  The global temperature change is about 6C during the same time.  Thus the CO2 changes about 15 ppm for each 1C change in temperature.

    For AGW we have changed the CO2 from about 270 to 400 or about 130 ppm of CO2.  The temperature has risen about .8C so far.   We might expect ocean outgasing to decrease CO2 concentration in the ocean by the equivalent of about 10 ppm CO2 in the atmosphere. (the deep ocean has not come to equilibrium.  This explaination is a rough estimate)  

    According to Henry's law, the solubility of CO2 is directly proportional to pressure of CO2.   The increase in pressure has increased the solubility of CO2 about 130 ppm which is over 10 times as much as the solubility of CO2 has decreased from the increase in temperature.

    The ocean acidification narrative is correct because the increase in solubility from pressure increase is so much greater than the decrease in solubility from temperature.  The situation was different during the ice ages because the change was slow and the difference in CO2 concentration was smaller.

    As the moderator points out, the increase of temperature may cause major problems in the future as the deep ocean heats up.  After enough temperature rise the ocean will not accept any more CO2 (the temperature affect increases as the temperature increases).  Then the CO2 in the atmosphere will rise more rapidly.  The surface few hundred meters will stay acidic in any case.  The rapid change in acidity is difficult for ecosystems to adapt to.

    This calculation is old news to people who have researched the facts about AGW.  Your posts would come across better if you asked questions about what you want to learn instead of suggesting that scientists have made major errors.

  19. Maybe this isn't the appropriate thread - this article might apply to several arguments, but CO2 lag seemed to fit. Brief on LiveScience on observed greenhouse effect(vs. modeled):http://www.livescience.com/49950-greenhouse-effect-measured-us.html

  20. (Moderator, forgive the funky link. Policies/firewalls here break some features of websites - I see a basic comments box, no tabs.)

    Response:

    [RH] If I'm not mistaken, you can also just type in the html code to embed links. If you know a little html that might be a workaround.

  21. Looking at the Temp and CO2 chart, the striking thing to me is the regularity of the events and the peaks.  Seems hard to refute that we AREN'T just in another peak cycle.  How can this be refuted when all we have is relatively miniscule time slices of human impact to compare?  Empircally incompatible.

  22. TGU, we are "in another peak cycle"... otherwise known as an interglacial. The current interglacial began about eleven thousand years ago when CO2 levels rose to ~280 ppm (from a low of ~180 ppm during the previous glaciation). They then stayed at about that level (+/- 15 ppm) for thousands of years... until, starting around 1850, they began growing at a rate orders of magnitude faster than anything in the Vostok chart above. We are now at 400 ppm.

    In short, we were at the peak of a natural cycle which plays out every ~100,000 years... and then in ~150 years humans drove up the atmospheric CO2 level by an amount greater than the entire range of variation over the course of that natural cycle, with more still to come. That's how we know that we aren't "just" at the peak of the natural cycle... we started there, but are now far far above the range that cycle has ever experienced.

  23. TGU

    Try a simple calculation. CO2 concentrations vary over a glacial cycle between around 180 to 280 parts per million (ppm). The fastest rate of change is during the warming phase when they vary by that much over perhaps 10,000 years. Thats 1 ppm/century.

    Today CO2 levels are rising at around 1 ppm every 22 weeks!

  24. "How can this be refuted when all we have is relatively miniscule time slices of human impact to compare?"

    Well the usual way - decades of hard work doing measurements and examining the evidence.

    A couple of things to consider. The natural glacial cycle is driven by regular cycles in the earth's orbital parameters. The change in solar radiation at around 65N is tightly correlated with the glacial cycle because of feedbacks in albedo and GHGs that ensue. Eg see Hansen and Sato 2012. 

    The maximum milankovich forcing per century at 65N at 0.25W/m2. Compare that 1.66W/m2 from CO2 alone operating not just at one region of the earth but over the whole globe. If the natural cycle was dominant, then we would be cooling slowly now.

    Secondly, the orbital cycle have been around a long time but they can only induce the glacial cycle when global temperatures are low enough for the albedo feedback to cut in. The last time we had 400ppm CO2 in atmosphere was in the Pliocene and there were no glacial cycles then.

  25. TGU,

     You are talking about the uncertainty principle where there is never enough measurement to satisfy all consumers of science. Science, in the end, is about consensus and it starts with nomenclature.

     Do you know what 'error value' is?

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