Why Temperature Lags Behind C02 - another "global warming myth" explained

Read time: 3 mins
One of the more popular excuses right now among those who still seem to think global warming is a “myth” made up by left-wing scientists and an underground network of communist politicians, is the fact that in the earth's long history scientists have observed that increases of CO2 in our atmosphere have lagged behind rises in temperature.

This is in the minds of many, including climate science “experts” like John Stossel at ABC News [video], puts to rest the whole idea that CO2 has anything to do with temperature.

Question: if John Stossel and others are so certain that this temperature/C02 lag somehow brings into question the theory of global warming, wouldn't scientists have heard of this and have accommodated for it in their research?

Answer: of course they have.

I asked one of the top climate scientists in the world, Dr. Andrew Weaver from the University of Victoria, to explain the fact that C02 lags behind temperature rise.

Turns out that the answer is quite simple.

It also turns out, that Dr. Weaver is putting the finishing touches on a new book called Keeping our cool: Canada in a warming world, and he has a whole section on the very topic of C02/temperature lag that he kindly sent on.

Here's Dr. Weaver's simple explanation excerpted from his new book:

“Antarctic ice core records also contain valuable information regarding the relationship between temperature and the greenhouse gases carbon dioxide and methane.

It's only during the slow deglaciation process, however, that sufficient resolution is available to allow scientists to explore the statistical relationship between temperature and carbon dioxide.

Several groups around the world have independently examined a number of different Antarctic ice cores and found that during deglaciation, the local changes in Antarctic temperature led changes in carbon dioxide by about 800 ± 600 years.

That is, temperatures changed first and then greenhouse gas levels followed, precisely as one would expect.

The greenhouse gases act to amplify the otherwise small changes in seasonality associated with very long timescale variations in the Earth's orbital configuration.

Feedbacks, like those I discussed earlier in this chapter, act to amplify the level of carbon dioxide, methane and water vapour in the atmosphere. These cause further warming.

So the next time you hear your favourite global warming naysayer point out that carbon dioxide lags temperature by 800 years in the glacial record, don't be surprised. That's exactly how it must be.

There were no coal burning plants 21,000 years ago spewing carbon dioxide into the atmosphere.

Carbon dioxide levels increased in response to warming thereby amplifying this warming further.

Remember that changes in the Earth's orbital configuration affect seasonality, and not the total amount of radiation the Earth receives from the sun in any given year.

By itself, a change in the Earth's orbital configuration does not cause global warming or cooling; the small signal must be amplified, and this is precisely what changes in surface albedo, carbon dioxide, methane and water vapour do.

That is, it doesn't matter whether you put carbon dioxide in naturally or unnaturally, the fact remains that it is a greenhouse gas and traps outgoing longwave radiation.

And, we've known this for over 100 years. Cold climates can't be maintained without a depletion of greenhouse gases and warm climates can't be maintained without an excess of greenhouse gases.”

Get DeSmog News and Alerts


I remember when Weaver was a serious scientist about 10 years ago. I didn’t buy his model-based conclusions then, but I certainly respected him.

Now he’s become just another climocrat, scuttling around, trying to discount new data by rationalization, and writing jabberwocky like the stuff you’ve quoted here.

BTW, “one of the leading climate scientists in the world” is an oceanographer and a skilled computer programmer who self-identifies as a climatologist. Nothing wrong with that, but it’s sad that, as he has become more and more deeply dedicated to his cause, he has morphed from scientist to climocrat.

Zog, you’ve coated Weaver quite completely with mud but it seems quite thin. Is there anything substantial there? What new data has he discounted?

Before responding, why didn’t you at least read the quotation that inspired my comment?

As to mudslinging - most of the regulars on this blog (you seem to be the principal exception)post nothing else with respect to scientists in the opposing camp. If you wish to classify my observation that Weaver has wandered away from science into proselytism as mudslinging, so be it.

If I want to know whether to pay attention to someone’s opinions on a subject, I generally check his/her publications. Turns out Weaver’s published scads of research in the field of atmosphere & oceanography etc. during the past 10 ears or so (since you decided that he “jumped the [scientific] shark”). Looks pretty solid to me, and certainly more than some of the prominent “scientists in the opposing camp.” Another fellow “who self-identifies as a climatologist” is a former geography professor (you all know who I mean) who hasn’t published any peer-reviewed research at all in that period of time. Hmm… who to believe, who to believe?

I wouldn’t say that he woke up one morning 10 years ago and suddenly decided to shift from scholarly inquiry to extremely combative defense of AGM in the media. His decline was fairly gradual until a couple of years ago, when the transition appears to have been complete. He takes any questioning of his results as personal affronts and speaks of non-believers much more harshly than anything I’ve said about him here. He has also said (and this is an exact quote), “We don’t need more science”.

As far as the “other fellow” to whom you refer, he is the mirror image of Weaver, and I sometimes wish that he would cool it. As you well know, we have much more credible champions than him but, rather than address their ideas, warmists prefer to sneer at them as “deniers” or dismiss them as “tools of Big Oil(TM)” This happens not only at DeSmog but even over at RealClimate with its pretensions of scholarship.

His decline was fairly gradual until a couple of years ago, when the transition appears to have been complete. He takes any questioning of his results as personal affronts and speaks of non-believers much more harshly…

Now what does this describe? Among other things, it perfectly describes the reaction of a reasonable man to an increasingly unreasonable opposition. There are times when losing your temper really is the appropriate response, let alone a forgivable one.

And since I know you’re just an objective guy with no axe to grind, ZOG, I’ll fill you in on something: making unfounded, categorical assertions about someone’s professional ability or integrity is harsh, no matter how “politely” you word it. It’s called smugness, and Prof. Weaver would be well within his rights to respond to your sanctimonious judgment of his character in a personal and harsh way.

Smugness, maybe; closer to libel I would think.

And Zog writes: “we have much more credible champions than him.”

Who is “we” Zog? And what “champions” would you consider to be credible?

Dr Weaver explains very clearly and simply the cause of CO2 lag behind temperature rise and you accuse him of proselytism? I failed to detect any preaching or some sort of cult-conversion efforts.
Do you have, or are you aware of any valid data that would put any of his observations in dispute?
As far as the opposing camp is concerned; posting anything from them can only be considered to be deceitful. Their “observations”, at best, can only be considered to be “buffet science”. They take what they want and leave the rest.

You haven’t helped me out here very much, Zog, but I think what you’re implying is that Weaver has disregarded the “new data” that CO2 followed climate change in geological history. I didn’t get it because those data are not new. Here is a quotation from a webpage last updated in year 2000: “Whether the ultimate cause of temperature increase is excess CO2, or a different orbit, or some other factor probably doesn’t matter much. It could have been one or the other, or different combinations of factors at different times in the past. The effect is still the same. Nevertheless, the scientific consensus is that GTGs account for at least half of temperature increases, and that they strongly amplify the effects of small increases in solar radiation due to orbital forcing.” – see: http://www.daviesand.com/Choices/Precautionary_Planning/New_Data/

This does not differ significantly from what Kevin’s quoting of Weaver indicates. Speaking of quotations, your quote of Weaver below (“We don’t need more science”) – I can’t find the full quotation (please point to it), but I remember him saying something like, We don’t need more science to decide to act. He did not say something that would support your claim that he’s no longer a serious scientist like, say, the science of climatology had reached its pinnacle.

Finally we arrive at the mudslinging part. I was complaining that your smears weren’t substantive. It’s okay that Tim Ball gets smeared because he misrepresents both himself and the issues. (And the reason for the focus on him is because the [Canadian] media puts him in stories for ‘balance’ more often than it does, say, Lindzen. Have you written to newspapers asking that they get somebody more credible?) You have not substantiated the mud. Your exact quote, as I’ve indicated, is incomplete, and not a single citation or link has been offered to bolster your assertion that he’s no longer a serious scientist.

The Vostok drilling isn’t “new” but much of the interpretative work is. AGW proponents have mostly tended to ignore the question of CO2 lag or “do a Gore” and blatantly misrepresent it.

The paragraph immediately preceding the one you quoted is sound science with which I have no problem at all.

“The main significance of the new data lies in the high correlation between GTG concentrations and temperature variations over 420,000 years and through four glacial cycles. However, because of the difficulty in precisely dating the air and water (ice) samples, it is still unknown whether GTG concentration increases precede and cause temperature increases, or vice versa–or whether they increase synchronously. It’s also unknown how much of the historical temperature changes have been due to GTGs, and how much has been due to orbital forcing, ie, increases in solar radiation, or perhaps long-term shifts in ocean circulation.”

A neat summation.

It’s unfortunate that the authors then felt constrained to write the paragraph that you quoted.

“Whether the ultimate cause of temperature increase is excess CO2, or a different orbit, or some other factor probably doesn’t matter much. It could have been one or the other, or different combinations of factors at different times in the past. The effect is still the same. Nevertheless, the scientific consensus is that GTGs account for at least half of temperature increases”

Read that again, carefully, especially the last sentence, and try to find the science in it.

I did misquote Weaver. What he said wasn’t “WE don’t need…” but “YOU don’t need more science.” with reference to his absolute certainty that the science of AGW is “settled”. I was watching the dear old CBC (about the 37th rerun of “The Denial Machine” I think) and, since I had pen and paper handy, I wrote it down.

AGW proponents have mostly tended to ignore the question of CO2 lag or “do a Gore” and blatantly misrepresent it.”

That is a lie. I have seen it explained on RealClimate and elsewhere often.

For instance, here: http://www.realclimate.org/index.php/archives/2007/04/the-lag-between-temp-and-co2/

Hey ZOG, that webpage wasn’t trying to explain all of the science. It was summarizing findings for some forestry group. The fact that this consulting company’s report is consistent with Weaver’s explanation shows that the interpretation was not new even before 2000. ZOG, you don’t deny Tyndall’s findings, right? Then why be obtuse wrt the fact that CO2 released during interglacials enhanced the greenhouse effect?

ZOG, please have your pen and pad ready again during the 38th rerun so you can get the full Weaver quotation and the context. Thanks.

This is meant to be positive advice. Get off your model-based computer, get into your model-based car, drive to the model-designed library, and do a little reading, if you can’t do your own inquiry.

That is in response to

“I remember when Weaver was a serious scientist about 10 years ago. I didn’t buy his model-based… “.

…As if “ZOG” studied actual climate science 10 years ago.

ZOG, Weaver is Canada’s most prestigious climatologist. He is an editor of the very well-respected “Journal of Climate” and is a leading author of the IPCC reports. Anyone who smears his name is completely out to lunch and should have their brain, heart, and soul examined. Anyone who tries to sully his reputation has no conscience whatsoever, as Weaver is a very nice man and knows his stuff.

I also noticed that you, ZOG, never attempted to refute the science which he researches. Is that because it is so solid that it is impossible to crack?

ZOG, you really showed what type of person you are.

Propaganda ‘science’ has been happening more and more; the scientific basis for banning DDT is missing! Millions have died from malaria. Last year the WHO lifted the ban… too bad for the millions of people already dead.

Propaganda junk science led the USSR to develop the dangerous Chernobyl reactor and the reactors for their nuclear submarine fleet as well. A political hack insisted their science was so superior to the capitalist west that cooling and containment were unnecessary. Now I guess Gore has lowered us to the USSR standard.

Inclusions from ice core are not valid for measuring ancient CO2 or temperature dependent isotopes because ice is an open system. It can take 100s of years for snow on a glacier to turn to ice (if ever) and the entrapped gasses and fluids are totally unreliable.

The most important information you can have is that CO2 has a property called retrograde solubility. Unlike most substances, it dissolves in cold water rather than hot. As earth heats by natural causes, CO2 is released from the slightly warmer ocean and if earth’s oceans cool CO2 goes into solution. Shake up a warm beer if you don’t believe me. CO2 trails natural warming.

I guess what I am getting to is that the polarization of society between arts and engineering has left the arts side of the population vulnerable to big expensive scams, and propaganda. No one doubts that the climate changes. It always has and always will.

Fortunately the UN IPCC report is being criticised by real scientists inside and outside. Beliefs are not enough! Seems like - is not a scientific term.

Fran Manns

What are you talking about? Is this your area of expertise? Your DDT claims are all wrong:
From there you went to CCCP and your guess that Gore “has lowered us” to the Soviet standard. Then on to some undisputed points about CO2 being less soluble in warm water. Finally to something about the Arts side of the population being vulnerable and thank goodness that the IPCC is being criticized. Wow. I suggest you spend some time reading and then try to use scientific arguments to discredit the science. Use political arguments to argue about the policy, not the science. Thanks.

Again, your ilk bring out the old “Soviet” card in an attempt to “rally the troops” (i.e. the ideological Right). The sign of a troll, one who yet again cannot refute the science of climate change, but tries to smear the IPCC and mislabel it as a political organization (rather than the scientific organization that it is).

This is a hoot.
Two sides unprepared to listen to eachother. Not a single one of you hasn’t presented proofs or access to them. You have all settled with presenting your own views, no matter what you’ve read. That is not how we do science.