A Few Things Ill Considered

This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.


Objection:

In the geological record it is clear that CO2 does not trigger climate changes. Why should it be any different now?

Answer:

Given the fact that the human species and our industrialization is rather unique in the history of planet Earth, do we really need to see some kind of historical precedent for CO2 triggered climate change before accepting what we observe today? Surely unprecedented consequences are not far fetched in the face of unprecedented events. But putting this crucial objection aside, history does indeed provide some relevant insights and some rather dire warnings.

During the glacial/interglacial cycles, CO2 concentrations and temperatures show a remarkable correlation. Closer examination reveals that CO2 does not lead the temperature changes, but actually lags by many centuries. Even so, the full extent of the warming can not be explained without the effects of CO2. Though this period does not demonstrate greenhouse gas initiated warming, it does lend support to the importance of CO2 and CH4 in setting the planetary thermostat.

There are also events in geological history where sharp rises in temperature appear to be initiated as well as driven high by very large spikes in greenhouse gases not unlike what fossil fuel emissions are on the way to being today. The Paleocene Eocene Thermal Maximum is such a case. Roughly 55 million years ago, ocean pH levels dropped drastically and global temperatures rapidly rose over 5oC. The resolution of proxy records that are available indicate that this happened in a period of time no longer than 5K years, but it is not possible to know if it happened even faster. The likely cause of this event was massive releases of methane from the ocean floors, perhaps due to some smaller warming or changes in sea level. It took over 100K years for the ocean, atmosphere and temperatures to return to their previous state. The result was a mass extinction event that took millions of years to recover from.

We can also look at the formation of the Deccan Traps. This massive and sustained volcanic action also altered the atmospheric chemistry and caused a drastic climate change, one that lead to the extinction of the dinosaurs. The theories of Snowball Earth involve the build-up of greenhouse gases as the mechanism by which the earth eventually escaped its frozen state.

So it is simply untrue that history lacks some precedent for greenhouse gas driven warming, and in fact the precedents that are there are rather dire warnings.


This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.


“Historically CO2 Never Causes Temperature Change” was first published here, where you can still find the original comment thread. This updated version is also posted on the Grist website, where additional comments can be found, though the author, Coby Beck, does not monitor or respond there.

Comments

  1. #1 Tim Wells
    August 21, 2008

    I was referred to this page because of my last posted comment.It was to do with the lack of evidence that CO2 is a driver of climate.I must now say that it is very disappointing to be referred here and not to receive any kind of a logical answer.
    I will start off by repeating: There is no eveidence that CO2 drives temperature or climate!
    About the ice-cores and CO2:they demonstrate clearly that temperature rises first,and THEN CO2 follows.Temperature also falls first,and THEN CO2 follows.
    CO2 and CH4 are greenhouse gases,and therefore add marginally[only] to the warming,but they DO NOT and never have DRIVEN the warming!
    Now in regards to the Paleocene Eocene Thermal Maximum.There is NO evidence that CO2 or CH4 were the initiators OR the drivers of this event.None!The cause is UNKNOWN.Exactly the same for the so-called Deccan Traps.

  2. #2 coby
    August 21, 2008

    Tim, you are revealing yourself as completely closed-minded and uninterested in actually thinking for yourself. Every one of your points is directly addressed in this artcle. If you see a flaw in the logic or incorrect assertions then let’s hear about it.

    You can’t just pretend away what I have written, point out an error.

  3. #3 timwells
    October 21, 2008

    Enough of the low-key insults Coby.You have not given in your article ANY evidence that this temperature event has been driven by greenhouse gases.The only thing you have done is to speculate about the cause of the event,and I have called things correctly by saying that you have not produced any evidence to validate your speculation.That is where your “incorrect assertion” and your “error” is.Read your own words!! “apppear to be” and “likely cause” and “perhaps due to”.
    So dont be so rude as to suggest that I dont think for myself.Do a bit of thinkling of your own and you may start to understand the difference between wishful assertions and verifiable evidence.

  4. #4 coby
    October 21, 2008

    Tim, it is really hard to know what to tell you when you baldly assert things like “there is NO evidence”, there is plenty and I have provided it. You ignore what I say and instead simply restate your initial position (ie about the lag time).

    Let’s try another angle: what would you consider to be credible evidence that CO2 is causing the current warming trend? How about the PETM event, what would you consider to be credible evidence that this spike in temperature was caused by a spike in greenhouse gases?

  5. #5 timwells
    October 29, 2008

    I will try again Coby.Please state in just 5 or 6 lines what verifiable evidence you have that CO2 drove the PETM event.Dont run away from it this time-present your evidence.
    And you have changed the subject in your second paragraph,presumably because you cant sustain your case.Now you are asking ME for evidence!Are you serious?Let’s try to be rational here.

    You make an assertion,which you have not presented any evidence for,and then you want me to tell you what the evidence to support your assertion should be !!
    Read carefully, YOU ARE MAKING THE ASSERTION[I am not]!!!BACK IT UP WITH EVIDENCE. [Do you understand what evidence is?]
    You have asked me to “point out an error”.
    Your “error” appears to be that you dont understand the scientific method and what constitutes “evidence”.In your article above you give information about the event,but you dont give an evidence based explanation of it’s cause.Do you understand that?Words like ‘appear to be’,’likely cause’,and ‘perhaps due to’are not evidence!They are ideas only.Theories about the cause are not evidence.Evidence is REAL DATA.
    You say that ‘….there is plenty and I have provided it’.
    You need to understand that you have not done anything of the sort.Unfortunately this only confirms what I suspect,and that is that you may be unaware of what constitutes ‘evidence’ in science.Please try to differentiate between evidence for the ‘existence’ of the event and evidence for the ’cause’ of the event.In the same vein,there is stacks of evidence for the ‘existence’ of global warming,but only theories to explain the ’cause’ of it.
    In summary then,in reference to the subject of this thread,please refute[using verifiable evidence]the sceptic statement,”Historically CO2 never causes temperature change”.

  6. #6 timwells
    October 29, 2008

    In answer to your question,
    “What would you consider to be credible evidence that CO2 is causing the current warming trend?”
    2things;
    First,if temperatures had followed CO2 in the past.
    Second,if the atmosphere showed the ‘hotspot’ heating pattern of increased greenhouse warming.
    Please now return the favour by telling me what evidence would convince you that CO2 has not been responsible for most of the observed warming?

  7. #7 Peter Doidge
    February 17, 2009

    I have found the comments above only recently, and it is now more than four months since they were first posted, but the remarks of Tim Wells deserve a response.
    Wells appears not to know that it is accepted in paleoclimate circles that the PETM was triggered by GHGs. To quote from the abstract of a quite recent paper: “The Paleocene-Eocene thermal maximum (PETM) has been attributed to a sudden release of carbon dioxide and/or methane…..These correlations support the view that the PETM was triggered by greenhouse gas release during magma interaction with basin-filling carbon-rich sedimentary rocks proximal to the embryonic plate boundary between Greenland and Europe.” (Michael Storey, Robert A. Duncan, Carl C. Swisher III, Science, v.387, p.587 (2007).
    From the text of the same paper:
    “The initiation of the PETM is marked by an abrupt decrease in the delta13C proportion of marine and terrestrial sedimentary carbon (1, 6), which is consistent with the rapid addition of >1500 gigatons of 13C-depleted carbon, in the form of carbon dioxide and/or methane, into the hydrosphere and atmosphere (7). The PETM is thought to have lasted only 210,000 to 220,000 years, with most of the decrease in d13C occurring over a 20,000-year period at the beginning of the event (8).”

  8. #8 coby
    February 17, 2009

    Thanks for answering that Peter. I had intended (and still do) a new post, actually two, to answer that comment. One to make a public challenge of the same question I asked him: “so you’re a “climate sceptic”, what evidence would it take to convince you” and one to answer his reasonable question: what would convince me that AGW is not occurring.

    Also, re CO2 initiated warming, there is this post.

  9. #9 tim wells
    April 17, 2009

    WRONG!!There is no evidence that the addition of 1500 gigatons of 13C even occurred!It is THEORISED to have occurred to balance out the carbon mass equation.Moreover it still cannot explain the rapid temperature increase.Plate rifting is also just an idea,and is not proven to have happened at this time.The spike in temperature during the PETM has not been shown to be caused by CO2.

  10. #10 coby
    April 17, 2009

    Tim, it is an extremely unproductive style of discourse you employ. Peter (comment 7) provides an answer with quotes and citations from peer reviewed research and you simply pontificate and contradict with no evidence to support your points.

    Why should we take you seriously? How about a logical train of thought together with some supporting evidence?

  11. #11 pat
    April 17, 2009

    The two examples listed in the original detail were for methane and a volcanoe not CO2. The last quote stated methane or CO2. since methane is roughly 100 times the GHG that CO2 is In would presume methane. The question is whether small changes in CO2 give meaningful global warming. I say no. check the temp/CO2 correlation it sucks. 11 years with no warming (actually slight cooling) per satelite data. when GW ranted about accelerating rates of warming. Ocean temps are also falling. The only thing propping up GW is Hansen cooking the books at Nasa. I have researched everything that I can find and the “deniers” make a better case. Mostly you get alarmism and faulty logic from the GW crowd. I am ready to be educated. please respond.

  12. #12 Adam
    April 18, 2009

    Pat –

    check the temp/CO2 correlation it sucks.
    Only if you look at very short periods.
    http://www.manchesterismyplanet.com/pictures/global%20temperature%20and%20co2%20levels_400x10000(1).jpg

    Or, more rigorously:
    http://moregrumbinescience.blogspot.com/2009/03/does-co2-correlate-with-temperature.html
    No one is trying to claim that there is a 1:1 relationship, or that temperatures increase monotonically over a period of increasing carbon dioxide concentrations.

    11 years with no warming (actually slight cooling) per satelite data.

    please see here:
    http://scienceblogs.com/illconsidered/2006/04/warming-stopped-in-1998.php

    Every single year of the 2000’s (except 2000 itself) is in the top 10 warmest years on record, in this supposed period of cooling.
    http://www.metoffice.gov.uk/corporate/pressoffice/2008/pr20081216.html

    The only thing propping up GW is Hansen cooking the books at Nasa.
    If you can provide some evidence, maybe we’ll know what you’re talking about. Otherwise, it’s just libel.

  13. #13 timobrienwells
    April 28, 2009

    Sorry about upsetting you Coby.But the fact remains that the cause of the PETM is still unknown.It can be “attributed to…” until the cows come home,but the cause is still unknown.In any case temperatures had started rising 3000 years before the PETM and they dont know what caused that either.

  14. #14 Vernon
    April 29, 2009

    Coby,

    A few points
    We know that CO2 is not a strong climate driver(see 1 below)
    We know that CO2 has never lead climate change (see 1 below)
    We have speculation on what caused the PETM but no evidence. The question is more one of, if GHG caused that 55 million years ago, why has it only happen once?

    1 – We know that CO2 is not a major driver of warming. As I stated in the other thread, the long term high resolution record (ice cores) shows that temperature rises and 800-2500 years later the CO2 starts rising. Further, the record shows that CO2 cannot be a driver since peak warming happens before peak CO2 in the record.

  15. #15 Richard Jensen, Ph.D.
    May 9, 2009

    I’m new to the debate, but so far I have been quite underwhelmed by the believer’s argumentation. This page is a prime example.

    Coby states: “During the glacial/interglacial cycles, CO2 concentrations and temperatures show a remarkable correlation. Closer examination reveals that CO2 does not lead the temperature changes, but actually lags by many centuries. Even so, the full extent of the warming can not be explained without the effects of CO2. Though this period does not demonstrate greenhouse gas initiated warming, it does lend support to the importance of CO2 and CH4 in setting the planetary thermostat.”

    Ok, let’s parse out just this one paragraph.

    First, “remarkable correlation” does not get you “cause,” as many people have pointed out. Yet, “cause” is what believers need to demonstrate (and the burden of proof IS upon them). However, Coby himself states in this passage that CO2 CANNOT be a (the?) cause of global warming, thereby undermining the primary point that believers must sustain.

    [Excuse me, but why rewrite (incorrectly) what you yourself just quoted? I said GHG's were not the initiator in this particular case. How do you get "CO2 CANNOT be a cause or global warming" from that? This is a very disingenuous debating tactic
    - coby]

    How does Coby’s own point contradict the causal argument? “Closer examination reveals that CO2 does not lead the temperature changes, but actually lags by many centuries.” So, if CO2 is a (the?) CAUSE, then here we have the first cause known to mankind that FOLLOWS its effects!

    So, let me get this straight… we have real-world, fairly recent data demonstrating marked, significant CO2 increases FOLLOWING a warming period (distantly, btw). Thus, we have a “remarkable correlation?” And from THIS, we are entitled to summarize the paragraph with the weak and utterly vague: “it does lend support to the importance of CO2 and CH4 in setting the planetary thermostat.”

    Whaaat? CO2’s “setting the planetary thermostat” long AFTER the furnace has gone on for awhile and then back off is supposed to convince me of its “importance,” nay, its CAUSAL role in “setting the thermostat?” Furnaces FOLLOW thermostats, not the other way around.

    [What you are arguing against here, and solely by ridiculing it, is the very possibility of a feedback effect. Your position is feed backs are impossible so there was no feed back effect durring the glacial/interglacial cycles. I will not bother debating that point.

    -coby]

    And this sentence is spectacularly fallacious: “Even so, the full extent of the warming can not be explained without the effects of CO2.” Here we have a textbook case of appeal to ignorance, and, worse, the appeal is fundamentally question-begging as well. This sentence, in effect, says: “We don’t know of any other factors (besides CO2, which is the very point at question), so it must be CO2 (even though the cause follows the effect)!” But the very point made by skeptics is that there is SO much that we don’t know! Here we are being BEGGED to trade an simple admission of abject ignorance for a “cause” that lags its effect!

    [I wrote: “Even so, the full extent of the warming can not be explained without the effects of CO2.” and your read “We don’t know of any other factors [...] so it must be CO2″. That is a remarkable leap, I am happy to let it stand for itself.
    – coby]

    This page was supposed to convince me of the CAUSAL role CO2 plays in global warming. THIS role is the primary thing under dispute. What little DATA cited in favor of CO2 as a cause is vastly interpretational and from tens of millions of years ago. As the data get more recent (and thus presumably more reliable and less a function of speculation and interpretation), I am handed weak and vague “correlations” rather than CAUSES. And flat-out counterexamples are simply “explained” away by fallacious hand-waving.

    [This page was not supposed to present the entire case for CO2's causal role in today's global warming, I wrote it, so I would know. Why would you think that? Like all the articles in this guide it is narrowly focused on the objection stated at the beginning. Please see this post for a primer on what is the evidence for CO2's role in today's global warming.
    - coby]

    I don’t yet know what the story is on global warming (or even if there is such a thing). My mind is not made up. But THIS sort of argumentation is anti-persuasive!

    [I highly recommend reading at least the Summary for Policy Makers from the latest IPCC report [PDF] if your interest is at all sincere.
    – coby]

  16. #16 coby
    May 10, 2009

    Hi Richard,

    Please see replies to your comment inline, thanks.

  17. #17 Paul in MI
    May 10, 2009

    Richard, thanks for your question. And Coby, thanks for your response.

    It seems we have now moved to a point that this “closed” subject is now debatable.

  18. #18 Sgt Sheff
    May 10, 2009

    Richard I like your style. Because of you I will remain a skeptic. I never had any intentions of going the other way, but you have innspired me to keep digging.
    Not to change the subject on this matter, but what are your thoughts on the sun having a role in the weather. Take for example Solar Cycle 24 that has yet to begin. I hope it starts soon, because I am tired of being so cold here in the sub-tropics of Pacific islands. Here it is May 11th, and it is still overcats and in the lower 70’s, I miss the warm sunny days of two years ago. Any way this is a great post keep it up.

  19. #19 Crakar14
    May 10, 2009

    Sgt Sheff,

    Coby has a thread dedicated to this subject,

    http://scienceblogs.com/illconsidered/2006/04/its-sun-stupid.php

    Mind you the “avoiders of fact” believe the sun plays only a trivial (if that) role in the climate.

    There is a bit there to read also a good site is solarcycle24.com.

    Cheers

    Crakar

  20. #20 Richard Jensen, Ph.D.
    May 11, 2009

    Coby responds: “What you are arguing against here, and solely by ridiculing it, is the very possibility of a feedback effect. Your position is feed backs are impossible so there was no feed back effect durring the glacial/interglacial cycles. I will not bother debating that point.”

    It is very convenient to “not bother debating that point.” Nothing about your original post or its links referred to a “feedback loop,” and that notion seems like a lot of hand-waving to me. Either CO2 is CAUSAL or it is not. Rather than to refuse to debate the critical point, why not actually explain EXACTLY how your cited data indicates a “feedback loop” (spanning hundreds to thousands of years), and EXACTLY how CO2 plays a CAUSAL role, when the data indicate that increased CO2 FOLLOWS increased global temperature. Please explain EXACTLY how we get a CAUSE following its supposed effect. Refusing to debate this point is a clear-cut punt on the primary issue.

    Coby continues: “I wrote: “Even so, the full extent of the warming can not be explained without the effects of CO2.” and your read “We don’t know of any other factors [...] so it must be CO2″. That is a remarkable leap, I am happy to let it stand for itself.”

    Again, a punt. I’m sorry to be blunt, but what you wrote is a textbook case of appeal to ignorance. I did not recast what you said uncharitably. I merely pointed out the implications of your statement. When you writing something like, “Cannot be explained without __________,” whatever you put into the blank is going to be a conclusion drawn from ignorance. Scientists are NEVER in a position to state: “Cannot be explained without….” Period! Just because you don’t happen to know another explanation at this moment does NOT entitle you to claim that there IS no other explanation. Appeal to ignorance, just as I said.

    Coby, you then take me to task for casting the intent of this page too broadly. But, if this page is not designed to address the question of the CAUSAL role of CO2, then exactly what was its intent? I admit that you are here addressing a fairly “narrow” aspect of the entire global warming issue. But I can be forgiven for taking the intent just as I did, because the logical negation of your “objection” in the title IS to demonstrate that CO2 IS causal. You ask, “Why would you think that?” So, let me explain why I would think that.

    Your objection (which you intend to negate in this page) is: “CO2 never causes temperature change.” A simple logical derivation shows that your denying this objection MUST amount to the claim that CO2 (at least sometimes) CAUSES global temperature increases. I won’t provide that derivation, because the symbols will not appear correctly. But, I can “pull rank” as a logician and assure you that I am speaking the truth.

    So, there can be no denying that this page is STATED to intend to demonstrate that CO2 is (at least sometimes) CAUSAL. That is “why I would think that.”

    My interest is increasing, but, honestly, I continue to be amazed at the bad argumentation. I approach such topics this way: “Give both sides ALL their claimed data (don’t debate the data), and then see which side is even drawing appropriate inferences from their claimed data.” So far, it’s not looking too good for the global warming camp.

  21. #21 greg
    December 2, 2009

    While it may not be that CO2 is a historical CAUSE of climate change it is an experimentally verified fact that CO2 is a contributor to warming. Since CO2 is the only contributing factor over which we have any control then to counter global warming we must reduce greenhouse emissions.
    Another impotant point is that averages are a mathematical device to negate variance or range in the data. In my examination of raw data in 20 locations the incidence of hot days (over 30 degrees C) has risen 6 to 8 fold over the last 100years and this incidence has continued RISING since since 1998. This increase has often been balanced by an increased incidence of low temperatures associated with clear sky conditions in cooler months. Hence a small or sometimes zero change in the average. In biological systems the frequency of extremes are far more important than the average eg a single day exceeding 45 degrees causes far more damage than if all days were 0.7 C warmer.

  22. #22 Dominik
    July 10, 2012

    Hi there, me again. Coby, you are amazing, providing such an extensive blog with a great effort of providing us with logical links which we are missing!
    So, I found this page after two more hours of reading and pondering on “historical proof” (coming from “Natural Emissions Dwarf Humans”, “What’s Wrong With Warm Weather”, “no past no present”, in that order).

    I see some of my questions answered. OTOH, let me restate and reinforce here two questions concerning the PETM.

    I have already quoted this webpage on “Natural Emissions Dwarf Humans”:
    http://www.nature.com/ngeo/journal/v2/n8/full/ngeo582.html
    which basically says that CO2/methane can not be the sole cause for PETM temperature rise.
    I imagine your answer would be that it need not be, but chances are high that it is at least very likely that it was one of the main drivers of the feedback cycle at those times?

    Concerning the extinction event, quoting from wikipedia, which you quoted:
    “The PETM is accompanied by a mass extinction of 35-50% of benthic foraminifera (especially in deeper waters) over the course of ~1,000 years – the group suffering more than during the dinosaur-slaying K-T extinction. Contrarily, planktonic foraminifera diversified, and dinoflagellates bloomed. Success was also enjoyed by the mammals, who radiated profusely around this time. (….) The increase in mammalian abundance is intriguing. There is no evidence of any increased extinction rate among the terrestrial biota. Increased CO2 levels may have promoted dwarfing – which may have encouraged speciation. Many major mammalian orders – including the Artiodactyla, horses, and primates – appeared and spread across the globe 13,000 to 22,000 years after the initiation of the PETM.”

    So… extinction for some oceanic and dinosaur life forms, striving of most of the flora and mammal life forms? A possible reply could be, that first came the extinction in the course of ~1000 years, then the striving after 20.000 more years… which easily covers a whole homosapien’s span of existence (?). But the wikipedia article is not really clear on that, it could be that mammals were left largely untouched throughout the entire PETM and even enjoyed raised temperatures, as indicated by the great diversivication?