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Climate Hustle

Understanding the CO2 lag in past climate change

Posted on 5 January 2011 by Anne-Marie Blackburn

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, 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.

The only conclusion that can be reached from the observed lag between CO2 and temperatures in the past 400,000 years is that CO2 did not initiate the shifts towards interglacials. To understand current climate change, scientists have looked at many factors, such as volcanic activity and solar variability, and concluded that CO2 and other greenhouse gases are the most likely factor driving current climate change. This conclusion is not based on the analysis of past climate change, though this provides key insights into the way climate responds to different forcings and adds weight to the several lines of evidence that strongly support the role of greenhouse gases in recent warming.

This post is the Basic version (written by Anne-Marie Blackburn) of the skeptic argument "CO2 lags temperature". This argument actually peeped its way into the top ten during December but then "We're heading into an ice age" shouldered its way back to the #10 spot (so there's a real dog fight between those two to climb over each other in the rankings).

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Comments 51 to 100 out of 246:

  1. Sphaerica @50,

    To add to your and Phila's excellent discussions-- this Figure also places the radiative forcing from CO2 in context.



    The above image was sourced here, where a table is available.
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  2. #52: Albatross,
    That's a terrific summary graph of the mess we've put ourselves in. Great find!
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  3. To gary thompson.. As discussed previously on this blog and others you may be right that we should be in a cooling trend, but that it is being overwhelmed by AGW. The rate of cooling is so gradual that if you cant believe the data showing the current warming there is no way you can say there is a cooling signature. To say we haven't been warming really requires blatant cherry picking and a vivid imagination. The warming trend continues just as expected. But anyway when we look at the what should be cooling, and is actually warming the statement that AGW accounts for 80 to 120 percent of the current warming seems pretty accurate. Also more in line with this post, previously co2 was a feedback, in the current situation it is the driver. IMHO. I do like when Mr thompson comes here and posts, he is civil, and does make for a lively discussion.
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  4. Some questions for "skeptics" to think about (should they decide to do so):

    When the eccentricity of the Earth's orbit is at or near a maximum, and the precession phase is just right, the SH will receive more solar energy than the NH (or vice-versa). When this happens, the two hemispheres will be 180 degrees out of phase with respect to the amount of solar energy they receive. Yet in spite of this fact, for the past several hundred-thousand years, the two hemispheres have warmed and cooled together on Milankovitch-forcing time-scales, even during these times of maximum hemispherical solar-energy imbalance. Why is this the case? Why didn't one hemisphere cool while the other warmed when these hemispherical imbalances of solar energy occurred? What kept the hemispheres "locked in phase" (on Milankovitch time-scales) with respect to warming/cooling during these times?


    Now go back a little over 35 million years. At that time, the Sun was slightly dimmer than it is now, and the latitudinal distribution of the Earth's continents was almost exactly the same as it is now. So the total solar + land-albedo forcing was about the same (or ever so slightly weaker) than it is now. Yet the Earth's poles were nearly or completely ice-free, and the Earth was too warm to cycle between glacial and interglacial phases. Why?
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  5. apiratelooksat50 @ 29 - Biodiversity refers to number of species. Biomass refers to the total mass of living biological organisms at any given time and place

    I don't want to veer this too far off topic, however I would expect a person teaching environmental science, might have a better understanding of the relevance of biodiversity and how it pertains to biomass.

    The relationship holds true today, consider the incredible biodiversity and associated biomass of the tropical rainforest, compared to the dry forest. And the biodiversity of the coral reefs and the huge biomass compared to less bio-diverse shallow oceanic regions.

    Biogeochemical cycle studies of the Phanerozoic, support this view too. So what leads you to suppose the time of the dinosaur was any different?.

    I don't have a clue about the biomass at that time but your chart is not applicable.

    If you don't have a clue, how can you then claim it's not applicable?.
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  6. @ Sphaerica

    I'm more than familiar with the Wikipedia pages on ice cores, and I have taken time to read comments and papers published by the experts you refer to. They bear out what I said - that interpreting ice core data is fraught, even with all their expertise and the years they have spent working with the cores. I am not disrespecting them or their work - I am reflecting what seems to be their considered opinion.

    Can you point to a paper published by someone with suitable credentials, stating that the various problems I mentioned (Difficulty distinguishing local from global variation, and 'noise' from the inaccuracies inherent in the record. Hence my doubt about the wisdom of relying on a single core, or trying to 'refudiate' AGW on the basis of CO2 lagging temperature on the way down.

    If you compare different ice cores, you'll see significant variation between them. Vostok, for example, records a significant upwards blip in temperature, abOUT 8,000 years ago. Grip, at the same time, records an equal drop in temperature. EPICA doesn't show much of a trend at all (You see, I do have a Wikipedia+ familiarity with the topic). Is there any way of telling which represents a global change, local variation or just taint?

    FWIW, I'm no sceptic on climate change. I accept it is happening, it is largely our fault and it is going to have devastating consequences if we don't act. I was suggesting - to an apparent doubter - why some of the claims he made were dubious, based on my own limited understanding.

    It's a pity you failed to address the points I raised, either supporting them or countering them, preferring to snipe at me, personally. You had a chance to enlighten, but you missed it.

    As for my amateurism, if you're willing to pay me for my comments, I'll happily upgrade my status from 'rank amateur' to 'professional.'
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  7. Painting @ 55:
    I perfectly understand the relationship between biodiversity and biomass. The point I was making was that the gentleman to whom you were commenting was referring to the widely held belief (by some people) that during that time period there was a greater abundance of life due to the higher CO2 and resulting larger supply of producers and therefore larger consumers. (I'm not telling you he is right, I am just clarifying what he is saying.)

    And, FWIW, biomass and biodiversity don't always go hand in hand. An emergent field certainly has a greater amount of biodiversity than a redwood forest, but is severely lacking in the biomass department.
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  8. First it seems simplified science to imply CO2 is the main greenhouse gas since the water molecule absorbs in many parts of the Sun's spectrum and CO2 only in three main peaks. Because the absorbed energy is transferred by collision the retention time in the atmosphere is not a factor ie water is a much more significant greehouse gas.The lack of correlation between CO2 as a causal factor and consequential temperature rise has been increasingly obvious since 1998 when the temperature apparently started to level off with a continuing rise in CO2 level. What is baffling is why a vastly complex set of interrelated factors should have ever come to be portrayed as an oversimplified single cause /effect relationship which appears to have now dominated the debate and even got as far as a United Nations supported international seal of approval. For anyone interested in some of the complexities can I be so bold as to suggest glancing at my paper on the Science of Global Warming posted on http://billpeddie.wordpress.com Bill Peddie, Auckland New Zealand
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  9. Bill - take a look at http://www.skepticalscience.com/argument.php
    Number 25 might help your confusion regarding CO2 vs. water vapor.

    Number 4 should clear up your confusion regarding 1998 and all the cooling you are having there in Auckland.

    Be sure and click through to read the article, and then drill down to the actual science if you need more convincing.

    No need to be confused!
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  10. Bill Peddie #58

    First it seems simplified science to imply CO2 is the main greenhouse gas

    This misconception has already been clarified several times for the benefit of the "skeptics" on this thread. Apparently, some of them have perfected their "skepticism" to the point that they no longer need to read comments.

    As for the remark about "simplified science"...well, of course. The unsimplified science takes up a huge amount of space, and would be indecipherable to most readers (especially the "skeptics," judging from this thread and others).

    What is baffling is why a vastly complex set of interrelated factors should have ever come to be portrayed as an oversimplified single cause /effect relationship which appears to have now dominated the debate and even got as far as a United Nations supported international seal of approval.

    Well, there are two possible explanations, as I see it. One is that you are mistaken. The other is that some shadowy global cabal has conspired to falsify decades of climate science for unknown reasons, but has done such a ludicrously shoddy job of it that any gifted amateur with a little spare time can knock down the entire house of cards by invoking some glaringly "obvious" phenomenon.

    That the latter position tends to be "skeptical" one speaks volumes about the nature of this debate.
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  11. #58 @Bill Peddle: The main reason that CO2 is identified as the mail cause of global warming is because it IS the primary cause of global warming, although not the only cause (eg deforestation is another and there are more). The complexities arise because of the myriad of secondary effects (such as ocean dead zones, acidification), feedbacks and interactions.

    The complexities are recognised and documented in scientific papers and popular science articles. Unfortunately these complexities can be and are often used by deniers to obfuscate the fundamental problem, which is that the waste being thrown into the air as if it was a huge garbage dump, is making the world warmer and forcing climate change - more frequent and worse floods, droughts, heat, intense rain events etc.

    A few years ago there were concerted efforts around the world to deal with the growing problems of landfill with rubbish, contamination of land etc. This problem is still ongoing. We are only just now starting to address the problem of 'air fill' with waste products such as CO2.

    Many of us are already suffering from the effects of treating the air as a garbage dump. If we don't do more to stop polluting our precious atmosphere very soon, many more people will suffer. The atmosphere is our only protection between earth and outer space and we are rapidly destroying it, effectively subjecting the earth to slow 'suffocation' by global warming.
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  12. @ Bill Peddie

    "First it seems simplified science to imply CO2 is the main greenhouse gas since the water molecule absorbs in many parts of the Sun's spectrum and CO2 only in three main peaks."

    I don't think anyone has suggested this. Water vapour is the major GHG. We emit both, and both absorb IR and heat the atmosphere. The difference between water vapour and CO2 is that CO2 is that it stays in the atmosphere for A VERY LONG TIME, where as whatever water vapour is put out is gone in a couple of weeks. That's why CO2 is critical.

    "Because the absorbed energy is transferred by collision the retention time in the atmosphere is not a factor ie water is a much more significant greehouse gas."

    Of course its a factor, because as long as CO2 concentrations keep increase, there will be more absoption, more collisions and ore heating. The CO2 doesn't just absorb once and then go away.

    "The lack of correlation between CO2 as a causal factor and consequential temperature rise has been increasingly obvious since 1998 when the temperature apparently started to level off with a continuing rise in CO2 level."

    The temperature rise you'd see over that period resulting from CO2 would be masked natural variation - yer solar fluctuations, yer el Nino and la Nino type stuff. that's why you can't look at a short term 'snap shot.'

    This is a back of a cigarette packet calculation, and I'm happy to be corrected if I've got it ENTIRELY WRONG. But here goes ...

    The CO2 concentration in 1995 was about 360ppm, in 2009 it was 386 - a 7.22% increase. Best estimates for the effect of doubling CO2 is about 3C, so a 7.22% increase in temperature would be 0.22C. Over that period, we've seen temperatures vary from 0.2C above anomaly to 0.6C above anomaly, a difference of 0.4C, enough to mask any trend over such a short span. The 5 year and 11 year running records show the underlying trend amid the short term variation.

    "What is baffling is why a vastly complex set of interrelated factors should have ever come to be portrayed as an oversimplified single cause /effect relationship which appears to have now dominated the debate and even got as far as a United Nations supported international seal of approval."

    It hasn't, actually. If I'm roughly aware of the complexities, then the information is easily available.
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  13. Bill Peddie, you'd be well advised to watch this lecture video before you post another message here: http://www.agu.org/meetings/fm09/lectures/lecture_videos/A23A.shtml
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  14. I assumed in my post that Bill Peddie #58 would twig to the fact that more water evaporates as it gets hotter (it's getting hotter because there is more CO2 in the atmosphere), which means there is now more water vapour in the atmosphere, which, because water vapour is a greenhouse gas, makes things warm up even more.

    On re-reading his post, it seems that he may not have made that fairly obvious connection between more CO2 and more water vapour. Where more CO2 is giving rise to more heat, which is giving rise to more water vapour, which is giving rise to even more heat. And he might not have twigged to the fact that rain is the effect of water vapour condensing into liquid water, which puts a cap on the amount of water vapour in the atmosphere at certain temperatures and humidity levels.

    Sometimes it's easy to miss the obvious, or pretend to do so.
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  15. Apologies for interrupting the discussion, but some of the usual nonsense has distorted some points:-

    1. In a continuous system, cause and effect is misleading, and even useless. Contribution rise and fall is more relevant, and more accurate.

    2. CH4 records outline the same pattern as CO2 records but not the identical measurements:-

    http://en.wikipedia.org/wiki/File:Vostok_420ky_4curves_insolation.jpg

    CH4 is more volatile, less persistent, and more indicative of ... swamps.

    3. The levels of glaciation illustrates the weak basic solar influence, not the dominance:-

    http://upload.wikimedia.org/wikipedia/commons/7/7e/Milankovitch_Variations.png

    The sun isn't a variation driver - it's the constant light-bulb that promotes stability. Only the gyroscopic motions of the earth give it a place in the cycles.

    4. Dust levels may strongly influence the shape of glacial/interglacial turnaround (stronger dust levels during the last and the current interglacial):

    http://en.wikipedia.org/wiki/File:Vostok-ice-core-petit.png

    5. The attempt to remove CO2 influence from glacial oscillations needs to show that the Greenhouse Effect does not exist. The anomaly that it is being artificially force-fed is critical to differentiating between natural behavior and AGW. Most pro-pollution arguments demand a 'cause and effect' with 'prove it' discussion - an attempted semantic victory over scientific reality.

    Anyone attacking the Greenhouse Effect with the 'not the historic warming cause' gambit, has a pro-pollution agenda. No one ever claimed it was the driver of inter-glacials or return to glaciation.

    6. There is one parallel to the current extended warming - the Hoxnian Interglacial (425kya-370kya). 'If' there is a common factor, it's may be the 'flood' event of Lake Agassiz emptying into Hudson Bay. Scablands to the west, the Mississippi basin south, and the Great Lakes carving east, all show geologic markers as flood-event basins. But the current stability (which is now being overturned by AGW) may relate to the anomaly of a Hudson's Bay drainage.
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  16. As frequently happens on this blog, one of my comments (@24) was deleted after some of you had responded.

    Thank you, Ann-Marie Blackburn, Phila and others for your responses. Yes, my comment about the "New Lysenkoism" was off topic, so I will keep that argument for another day. I spent a dozen years feeding at the trough of federal research dollars, putting project proposals together, so I understand pretty well how researchers "sing for their suppers".

    Ice cores show all kinds of interesting things and the list keeps growing as our analytical techniques improve. With regard to the first point in (#25), they show temperature leading CO2 concentration. While correlation does not imply causation it is clear that CO2 is not driving temperature changes on Vostok timescales.

    Does CO2 affect temperature at other timescales? I have no doubt that it does through all kinds of mechanisms including radiative heat transfer, the weathering of rocks, the decomposition of carbonates subducted in plate tectonic processes and so on. However, the effect of CO2 is subtle rather than dominant.
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  17. @GC: "With regard to the first point in (#25), they show temperature leading CO2 concentration. While correlation does not imply causation it is clear that CO2 is not driving temperature changes on Vostok timescales."

    Yeah, that's pretty much the point of this article. Glad to see you're finally coming around to reason: CO2 has most often been a feedback, not a forcing. This time, of course, things are different: anthropogenic CO2 is a forcing, not a feedback.

    CO2's effect, however, is anything but subtle. Observations confirm a 2.5 to 4C increase for a doubling of CO2.
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  18. @gallopingcamel #66

    I hope your comment (original #24) will come back once is acknowledged that "how they say it" is as important as "what they (apparently) say", at least, in the social, educational and moral aspects. Bearing the last in mind I think the deletion of your post may be a lost.

    Then, speaking of fuzziness but back to the topic, your "other timescales" suggests you are speaking of past eons. But, could you be precise about the last couple of centuries? Are you trying other people to infer you are suggesting that '"subtle" rather than dominant' is the effect of CO2 additions nowadays? Provided the answer is yes, could you back such an assertion with proper quotations, links and sound science?
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  19. gallopingcamel

    If you read my post again, you will see that the first sentence of the final paragraph states that CO2 did not initiate the shifts towards interglacials during the past 400,000 years. This does not mean that CO2 isn't responsible for current warming. Scientists are looking at current data and observations to draw their conclusions, not what may have happened in the past.
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  20. Sorry, it should read 'This doesn't mean that CO2 cannot be responsible for current warming'.
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  21. 56, Lurgee,
    I have taken time to read comments and papers published by the experts you refer to. They bear out what I said - that interpreting ice core data is fraught

    No, actually, they don't. They detail all of the considerations, how they should be handled, and what the margins of error are. You're simply choosing to interpret and portray it as such for your own purposes.
    Can you point to a paper published by someone with suitable credentials, stating...

    Clearly I can't, because you say you've already read the papers, and you're willfully choosing to misinterpret and misrepresent what you've read. If I give you a paper, you'll just come back and say you've read it, and that black is white.
    ...my doubt about the wisdom of relying on a single core...

    If you compare different ice cores, you'll see significant variation between them.

    Um... which is it? I thought you said there was only one? Obviously you know enough to know that there are different cores from different sites, in both the Antarctic and Greenland -- even though you seem to like implying otherwise (to fool the casual reader?). But that getting such cores is a very expensive operation, so there still aren't many. What makes you think people look at one to the exclusion of others?
    ...or trying to 'refudiate' AGW on the basis of CO2 lagging temperature on the way down.

    But that's not the issue. It makes sense that CO2 would lag temperature in that situation. It should. The problem with that argument against AGW isn't that CO2 doesn't or wouldn't or shouldn't lag temperature. The problem is that the mechanisms and interplay of events means it's comparing apples to oranges. It's like saying that you've always seen bullfighters kill bulls, so there's no way that a bull could ever kill a bullfighter.

    Sorry, but the ice cores are exactly what they are. They aren't perfect, but their imperfections are well understood and recognized, and they are perfectly acceptable and accurate proxies for CO2 levels and temperatures on the timescales in question.

    Saying anything else, with so much hand waving and "I've read..." is just blowing smoke to try to make skeptic arguments seem viable.
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  22. 66, gallopingcamel,
    While correlation does not imply causation it is clear that CO2 is not driving temperature changes on Vostok timescales.

    Does CO2 affect temperature at other timescales? I have no doubt that it does through all kinds of mechanisms

    Okay, at this point you are purposely simply ignoring the OP and the logic of the whole situation to blow smoke and present inaccurate information, while trying to make your position seem palatable and reasoned with faux skepticism.

    Go back and read the post, and think about it enough to understand it. There is a perfectly logical reason why CO2 would affect temperatures on long time scales, and also be influenced by temperatures on long time scales (feedback loop).

    Trumpeting one effect while ignoring the other is either using childishly simplistic thinking, or else presenting such childishly simplistic thinking in an effort to score points with the gullible that can't be bothered to think it through themselves to that degree.

    There are also perfectly good, obvious, and difficult to refute reasons (without just making stuff up, or purposely ignoring facts and logic) why CO2 is currently driving temperatures to unheard of levels at an unheard of rate.

    Saying "I'm reasonable, but..." followed by a lie and misrepresentation is still lying.
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  23. This article and subsequent threads have been very informative and do a good job of linking orbital changes to warming and cooling phases in Earth's history. The AGW theory failed to explain historically-known phenomena. The earth has experienced many periods of cooling and warming without the help of mankind.

    While it does appear that increasing CO2 levels, whether from anthropogenic sources or not, are having a documentable affect on the climate, it is also not clear how great these affects are, or may be. Label me a skeptic or denier, but I am not convinced that anything we are experiencing now cannot be explained by historical scientific observations that are completely validated (El Nino, La Nina, orbital variations, solar activity, PDO, volcanic eruptions, etc...). And, before you say I am "just a teacher", I have a B.S. degree in Biology and an M.S. degree in Environmental Engineering, and worked for 20 years in research, consulting, industry and environmental enforcement/compliance. Initially I was pro-AGW, but over the years as I've witnessed the shouting down and negative labeling of legitimate scientific inquiry that questioned components of the AGW theory, my position changed. Real science is always open to refutation and revision.

    In addressing man-made global warming, it is far more prudent and cost-effective to adopt a wait-and-see approach than to spend trillions now on what may or may not be a problem. Even if global warming becomes a problem, it’s going to be a problem regardless of how much we spend. Man-made contributions to atmospheric CO2 concentration total 15 percent and natural sources the remaining 85 percent, according to the U.S. Department of Energy.

    According to data from the National Oceanic and Atmospheric Administration’s Earth System Research Laboratory, between 1980 and 2006, the average global temperature increased 0.7 degrees F while atmospheric CO2 levels rose 48 parts per million by volume (ppmv). Fifteen percent of 0.7 degrees F equals 0.11 degrees F from man-made sources.

    Using United Nations climate-panel numbers, the atmosphere gains 2 ppmv a year of CO2 annually. After 10 years of a “do-nothing” approach, there would be an increase of 20 ppmv correlating to 0.3 degrees F. Of that increase, 0.05 degrees F would be man-made.

    To avert a miniscule amount of potential man-made global warming, according to some research, it would be necessary to shut down the entire global economy for a decade.

    By adopting a wait-and-see approach, we still have plenty of time to address even the worst-case predictions of climate change. Since it’s unlikely that we could do much to avert it, why not spend that money fighting the changes? Or, we could feed and educate everyone in the world.
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    Moderator Response: [muoncounter] Please avoid blanket statements like 'AGW theory failed to explain,' 'according to some research', etc. Document 'shouting down' of legitimate science and 'shut down the entire global economy' or such overt generalities cannot be taken seriously. There are multiple pages here at SkS that address your opinions; please use Search to find the appropriate threads. There is a lot to read and come to understand; you might want to see if your opinions and cursory research bear up to what the actual science has to say.
  24. @Sout

    There are problems with using ice-core proxies to determine past CO2 concentrations because it's likely that CO2 would have leeched out of the trapped air-bubbles, albeit very gradually, giving the appearance of stable CO2 concentrations over millennia. Stomata proxies show much more variability, although I am sure they come with uncertainties too. Just about every aspect of paleoclimate reconstruction seems extremely conjectural and uncertain to me.

    On topic, the hypothesis that positive feedback was the main cause of the earth's climate switching between glacial and inter-glacial states is one that sounds reasonable to me on the face of it, although I have seen nothing as yet to convince me that it definitely was the main cause. I have still yet to come across convincing evidence that CO2 is having (or can have) any desirable effect on global temperatures, and until I see some, I’ll remain sceptical on the idea of CO2-positive feedback. Orbital cycles seem a tad more plausible to me.
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  25. That's meant to be "discernable", not "desirable".
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  26. regarding #73, could someone please explain to me how, because humans account for 15% (or what ever) of the total CO2 in the atmosphere, we're only responsible for 15% (or what ever) of the increase in temperature.
    I've heard this argument before and can't quite make sense of it. I had kind of assumed that if the system was in balance and we come along and unbalance it, we're responsible for it tipping over... 100%
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  27. Les @76,
    Changes in orbital cycles make much better sense in initiating cooling/warming phases than changes in CO2 levels. With the exception of leftover thermal energy from the formation of the Earth, the sun is our energy source. The CO2 cycle is never "in balance" (refer to the chart). It fluctuates and the fluctuation is normal. A tipping point does not exist because it can't be quantified. There is no "normal" for temperature or CO2.

    We can refer to the climate we live in now as normal, but the fact is that humans have lived through many different climates and climate changes and adapted quite well to it. In fact, climate change has been linked to technological development, and evolution.
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  28. apiratelooksat50 @76

    Where is the evidence that suggests orbital changes are responsible for recent warming? How do timescales fit with this? Are all observations consistent with a warming caused by orbital changes? If you can provide a coherent theory that explains all phenomena, then you may have a point. Otherwise all we have is your opinion.
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  29. Anne-Marie Blackburn @78
    Where is the evidence that suggests orbital changes are NOT responsible for recent warming? They always have been in the past. I have to ask you, "Why is the current warming any different than the past."

    Please clarify what you are asking about timescales, and define the metrics on "observations consistent with a warming caused by orbital changes". While you are at it, please give a short list of the phenomena so we are talking apples to apples.
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  30. @77... Sorry, you haven't actually answered the question, you've changed the subject - in doing so, you seem to have negated your original point, as well as indulged in some classic "delilast" (hate that word) rhetoric. Be that as it may; I'm still holding out for an answer... I'm sure someone will help me.
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  31. gallopingcamel:

    Yes, my comment about the "New Lysenkoism" was off topic, so I will keep that argument for another day.

    I suggest you keep that "argument" under wraps forever, because it adds nothing intelligent or interesting to the discussion, and will only do further damage to your already minimal credibility.

    If you have a coherent scientific argument, you don't need insults. If you don't have one, insults will do nothing but underscore the weakness of your position.

    The same goes for your endless situational ad hominems about scientists having to "sing for their supper." Apparently, the principles of "skepticism" oblige us to mistrust thousands of climate scientists from all over the world, along with any hard data they've collected that upset us; instead, we should place our trust in an anonymous online commenter who's offering a tiny amount of anecdotal evidence in support of an argument that wouldn't be logically compelling even if the anecdote turned out to be true.

    If you can't recognize the absurdity of your basic assumptions, and the utter poverty of the argument you've built on them, I'm certainly not going to trust you to interpret the far more complex issue of AGW. I'll stick with actual science, thanks.
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  32. Actually, Pirate, your comment in 77 is not true. The climate of the last 5000 years or so has been, relative to the time span of homo sapiens, fairly stable. And humans have taken advantage of that stability, swelling to 6.5 billion and creating complex socio-economic relationships with the environment. We can't migrate as easily as we used to.

    I second Anne's question to you: are current global temperature changes consistent with "natural" causes such as insolation and Milankovich cycles?

    Yes, Les -- a bit of odd math. If we add 15% to the full bathtub and cause spilling, we're only responsible for 15% of that spillage? Ethicists may now grimace. The tub, one may argue, has a variable lip height, but it doesn't for humans. Humans have had a nice, stable lip height for several thousand years, and we've built a massive and delicate socio-economic system on that stability. We don't migrate as easily as we used to.
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  33. #79: "evidence that suggests orbital changes are NOT responsible for recent warming?"

    We know the orbital variations very accurately; you can look up the parameters on NASA webpages. Using those numbers, we can calculate what the solar insolation is at any point on the surface as functions of latitude and day of year. Point is, we are not in an anomalous warming period based on orbit.

    See Ice data made cooler for a nice graphic illustration of how this works and how it ties to the Vostok core record. That is a more appropriate thread for orbital questions.
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  34. @ apiratelooksat50 - I refer you to the articles on this page:
    http://www.skepticalscience.com/argument.php

    In particular, items 1 and 2, 11, 28, 41, 46, 48, 65 etc etc - or better yet, read them all, or as much as you can. Maybe spend a bit of time on greenhouse gases as this seems to be an initial stumbling block for you.

    For costs and practicality of sustainable energy, try climateprogress.org for starters - it has lots of good articles about what is happening around the world. Better to spend a penny today to save many pounds later.
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  35. apiratelooksat50:

    The earth has experienced many periods of cooling and warming without the help of mankind.

    You don't say.

    What is it with "skeptics" and strawmen? Would it kill you people to make an effort to understand what the theory actually says before you attack it? For that matter, would it kill you to read the article you're commenting on, which begins with the statement that "Earth’s climate has varied widely over its history"? Who do you imagine you're educating with comments like this one?

    I've never been very impressed with the resident "skeptics" on SkS, but the point-missing and strawman-building on this thread seems to be approaching a new low.

    Man-made contributions to atmospheric CO2 concentration total 15 percent and natural sources the remaining 85 percent, according to the U.S. Department of Energy.

    Upthread, I asked you to read Human CO2 is a tiny % of human emissions. Apparently, you didn't.

    In addressing man-made global warming, it is far more prudent and cost-effective to adopt a wait-and-see approach than to spend trillions now on what may or may not be a problem.

    Obviously, if you feel compelled to reject the basic science on AGW before you've managed to understand it, you're also going to reject the consensus on risk assessment. No surprise there. The fact that you go on to make an overheated, unsourced claim about how mitigation would "shut down the entire global economy for a decade" (whatever that means) is a good example of the contradictions inherent in this brand of "skeptical" thinking. But again, it's no surprise.
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  36. Phila @ 81:
    "Apparently, the principles of "skepticism" oblige us to mistrust thousands of climate scientists from all over the world, along with any hard data they've collected that upset us"

    Do you give the same respect to the thousands of anti-AGW climate scientists who can present their own hard data and interpretations?
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    Moderator Response: [muoncounter] Once again, unsubstantiated general statements like this limit any credibility you might seek to establish. The appropriate threads are There's no consensus, The science isn't settled and (presumably) The Oregon petition.
  37. DSL@82 & Philia: Thanks. I'm glad it's not just me who sees that argument as having more holes in it than a swiss cheese makers favorite cow herding socks...
    (or something equally stinky)
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  38. re #86 - What or who do you refer to when you write of 'the thousands of anti-AGW climate scientists'?

    My guess is that you are referring to climate scientists in general, all of whom are presumably anti-AGW because they understand better than anyone the harm AGW is doing to our earth.
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  39. apiratelooksat50 @ 79

    You made the claim that orbital changes are to blame for current warming - it's up to you to substantiate it with data and analysis, from the peer-reviewed literature of course. Since you have a degree and a MSc, I'm sure you're aware of this basic requirement. As for the timescales issue, orbital changes operate on relatively long timescales, whereas recent warming has taken place in a relatively short period of time. How do you reconcile this discrepancy, and do you have data to support this position?

    You logic is faulty. If I were to adopt it, I could claim that as all forest fires were caused by natural factors in the past, humans simply cannot be responsible for any recent forest fires. That's simply not how it works in science. You have to look at the evidence you have to draw your conclusions, not at what has happened in the past.

    Warming from different sources will leave different 'fingerprints'. We have quite a lot of observations now which are consistent with a warming caused by increased greenhouse gas levels. Now how would orbital changes explain the observed changes in Earth's radiation balance? Would such warming have a cooling effect on the stratosphere? Are there any predictions you can make based on the mechanism(s) through which orbital changes cause warming, and have these been verified? How would orbital changes fit in with the fact that nights are warming faster than days? All these questions, and more have been answered by the theory of anthropogenic climate change. Where is the theory on which you base your assertions?
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  40. apiratelooksat50:

    Do you give the same respect to the thousands of anti-AGW climate scientists who can present their own hard data and interpretations?

    That's a skillful way to phrase the question, because it allows you to presuppose the existence of an "anti-AGW" movement comprising "thousands" of climate scientists, without the need to bother with messy, confusing details like names, alternative theories and links to their groundbreaking papers.

    Unfortunately, the same approach that makes the question rhetorically useful to you makes it difficult for me to answer. The simplest response would be "No," but that would imply that I accept your premise, which I don't. In that regard, it's a bit like asking me when I stopped beating my wife.

    If you're actually serious, you could provide a list of recent, peer-reviewed papers by climate scientists that seriously call AGW into question, and we can assess their credibility on a case-by-case basis. However, the proper place for that discussion would probably be There is no consensus. You may want to read that page before picking that fight.
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  41. apiratelooksat50:

    Do you give the same respect to the thousands of anti-AGW climate scientists who can present their own hard data and interpretations?


    If there are thousands of anti-AGW climate scientists who can present their own hard data and interpretations, then you'll have no problem listing the names of 50 of them, right?

    Climate scientists, mind you. Not high-school graduates like Watts, but climate scientists.
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  42. ...adding, that if you decide to go this route, the logical starting-point would be to cite peer-reviewed papers that support your claims in this thread about "orbital changes," as suggested by Anne-Marie Blackburn @ #89.

    Being as there are "thousands of anti-AGW climate scientists who can present their own hard data," this shouldn't be too difficult for you.
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  43. @ Sphaerica

    << No, actually, they don't. They detail all of the considerations, how they should be handled, and what the margins of error are. You're simply choosing to interpret and portray it as such for your own purposes. >>

    The source you (rather patronisingly) referred me to - Wikipedia - describes te sort of issues I've referred to.

    << Clearly I can't, because you say you've already read the papers, and you're willfully choosing to misinterpret and misrepresent what you've read. If I give you a paper, you'll just come back and say you've read it, and that black is white. >>

    Again, ferocious personal attack. Are you, perhaps, confusing me with someone else? Was there another lurgee in the past, who merited such scorn? I'm new here, long time reader, first time poster, and I'm bemused at the reception my timid suggestions have received.

    I've not claimed to have read ALL papers. I posted, "I have taken time to read comments and papers published by the experts you refer to." I'm not pretending to have complete knowledge as you claim I am.

    So feel free to provide evidence that the experts regard the ice core record as 'clean' and relaibale, rather than a confused, torturous mess which, unfortunately, happens to the best we've got, and ever will get.

    << Um... which is it? I thought you said there was only one? Obviously you know enough to know that there are different cores from different sites, in both the Antarctic and Greenland -- even though you seem to like implying otherwise (to fool the casual reader?). But that getting such cores is a very expensive operation, so there still aren't many. What makes you think people look at one to the exclusion of others? >>

    You're not covering yourself in glory, I must say. The graph originally posted was based on data from a single ice core (Vostok). It says it right there, in italics, under the graph: "Vostok ice core records for carbon dioxide concentration and temperature change."

    << But that's not the issue. It makes sense that CO2 would lag temperature in that situation. It should. The problem with that argument against AGW isn't that CO2 doesn't or wouldn't or shouldn't lag temperature. The problem is that the mechanisms and interplay of events means it's comparing apples to oranges. It's like saying that you've always seen bullfighters kill bulls, so there's no way that a bull could ever kill a bullfighter. >>

    It's currently fashionable in denier circles to point to instances where CO2 has continued to rise or remained high for thousands of years after temperature has dropped - the most obvious example in Vostok being about 130K ago. They point to oddities like that, and use it to claim there is no link between temperatures and CO2.

    << Sorry, but the ice cores are exactly what they are. They aren't perfect, but their imperfections are well understood and recognized, and they are perfectly acceptable and accurate proxies for CO2 levels and temperatures on the timescales in question. >>

    Sounds like hand waving and smoke blowing to me.

    The ice cores are the only record we have for those time scales, and while they show general trends very well, there are contradictions around what they show. Even if their imperfections are "well understood and recognized," it doesn't mean they are resolved.

    It's like the satellite data that annoyingly doesn't show the tropospheric hotspot over the long term. Experts have dedicated their careers to reconciling this data, and still won't call it a reliable record of the long term trend.
    0 0
    Moderator Response: [muoncounter] Your credibility would be enhanced if you provided some links to valid research supporting your position on the quality of the ice core data. There is no need for extensive quoting from prior comments. Just add a link to the comment you wish to quote -- right click on the comment date/time stamp and 'copy link location', then paste into your comment.
  44. Lurgee,

    Do you perhaps regularly follow WUWT?

    Reason that I ask is that your potpourri of complaints seem to bear remarkable resemblance to "attacks" made on the ice cores etc. at WUWT.

    It strikes me as very odd that many skeptics cite the ice core data as evidence that climate has changed before, or that previous inter-glacials were warmer than this one, or that temperature leads CO2 et cetera, all in an attempt to refute the theory of AGW, or to try and play down the role of CO2.

    Yet, at other times when the ice cores are cited in the post under discussion here, then the 'skeptics' suddenly jump ship and feel obliged to try and demonstrate (with much arm waving) that the ice cores are hopelessly unreliable.

    You cannot have it both ways. This is just another example of the "skeptics" contradictory arguments.

    As for your reference to the alleged missing tropospheric hot spot, please take that "argument" to the appropriate thread, where you will see that your concerns and misunderstanding of the science have been addressed.
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  45. apiratelooksat50 - "I perfectly understand the relationship between biodiversity and biomass."


    Hmm, maybe not. The authors of that graph that I previously linked to, compared the data to carbon 13 isotopes because in their words "it's a proxy for global biomass". In other words comparing the relative proportions of the organic and non-organic carbon pools we have a crude proxy for biomass.

    Here's what they mean:



    Genera = dots. Squares = the inorganic/organic carbon ratio. Note how the two correlate?. See how during the time of the dinosaur both genera & biomass were much less than today?.

    Fraught with uncertainty of course, but preferable to to the location whence Shimkus extracted his assertion from.
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  46. 93, lurgee,
    The graph originally posted was based on data from a single ice core (Vostok).

    So Anne-Marie didn't bother to cite every proxy ever constructed. Big deal. It doesn't alter the argument one bit. No one on the planet (except you and the Wattsers) is contesting the ice cores, or the way they are being interpreted.

    Skeptics even cite the ice cores and the silly CO2-lags-temperature meme as a crowd pleasing favorite.
    So feel free to provide evidence that the experts regard the ice core record as 'clean' and relaibale

    This search through Google scholar identifies 3,630 papers and articles since 2005 which reference the Vostok ice cores alone. Is that enough evidence that the experts regard the ice cores as a reliable proxy?

    Now where's your evidence that even a handful of reputable scientists think otherwise -- that your position is anything other than your own personal opinion (albeit one shared by the whole neuron-starved Watts fan club — when it suits them).
    FWIW, I'm no sceptic on climate change. I accept it is happening, it is largely our fault and it is going to have devastating consequences if we don't act.

    That's really funny, because you say this, and yet you're a walking Poe's Law of denial (ice cores are suspect, there's no hotspot, etc., etc.).

    You're the second person on this thread (apiratelooksat50-I'm-a-HS-environmental-science-teacher being the other) who's come in, representing themselves one way ("who, me? Oh, I'm just an innocent bystander, but I just had this one little innocent question...") only to follow it up with a ridiculous litany of denialist tripe.

    Sorry, it's not flying with anyone.

    I haven't been to WUWT lately... has he put out a post tasking his faithful minions with visiting real science sites, and feigning helpless ignorance as a new way to ply his nonsense?
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  47. I'll take it, "So Anne-Marie didn't bother to cite every proxy ever constructed" is a concession that I wasn't shifting ground as you implied?

    Of course, I never suggested that she should, thanks for the straw, I'm sure I'll find some use for it.

    I can't believe you offer up a google blast as evidence. That's hardly scientific, is it? Though, amusingly, it is a tactic I've seen deployed by hard core sceptics. Do extremes ever meet, I wonder?

    My position seems to be backed up by Steig (2008), in the handily titled "Sources of Uncertainty in Ice Core Data," which listed numerous issues surrounding ice cores and said we need more ice cores and better cross referencing to reduce the errors.

    If you'd bothered to read #93 properly, you'd have noticed I wasn't disputing the existence of the tropospherical hotspot - just our ability to detect it over the long term.

    But carry on trying to paint me as some denier WUWT stodge, it makes a pleasant - though unlikely - change. There are some batshit crazy deniers out there who'd be wetting themselve to see me traduced thus.
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  48. Albatross, I can assure you I have nothing to do with WUWT? I opccasionally look at it, to see what the monkeys are being fed this week, but I'm not affiliated with it, nor a follower or adherent of it.

    My "potpourri of complaints" is reasonable doubt, backed up by comments made by an acknowledged expert (and not one who changes his tune as it suits, unlike John Christie). It seems a resonable enough position, given the various discrepancies apparent between the different ice cores. When hey're going in different ways, they can't all be records of global trends.

    I do not invest the ice core record with any more authority than I think expert scientists do - it is a record of general trends, albeit one that is complicated, telescoped and tainted. With millions of man hours of expert effort expended, we've still got uncertainties and discrepancies which can't be accounted for. It's amazing they've got thus far, and only deniers and (it seems) their equally fanatical counterparts on the other side of the debate invest them with such massive significance.

    As I remarked to S., above, my comments about the hot spot (or apparent lack there of) was intended to show the limitations of our ability to get data that accurately reflects the real world. If we can't detect (for a period of more than a few months) the hot spot we know is there, then how can we be so outrageously confident in the accuracy of the ice cores? Especially when they conflict?
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    Moderator Response: [muoncounter] Once again, it is difficult to put too much credibility in 'reasonable doubt, backed up by comments' from an uncited 'expert'. You provided one source (Steig 2008), which, upon review, is not exactly a ringing condemnation of ice core data. More specific sourcing makes for more credibility.
  49. Lurgee @98,

    Try again. Your potpourri of complaints is anything but reasonable as I and others have pointed out to you.

    And for the record, I am a scientist and frequently use Google Scholar. It is a very powerful, convenient and useful tool. Regardless, you seem to have elected to miss sphaerica's point.

    The limitations of (and caveats pertaining to) the ice core data are well established and well documented in the scientific literature-- making that observation is not even remotely new or original. And of course one can always improve the sampling and data processing techniques etc., but when working with these kind of data, demanding perfection is setting up the science for a fail, and that is quite a predictable tactic used by 'skeptics' who do not understand science. So your predecessors have long ago burnt that bridge for you.

    To place things in context, in all my years of conducting research, I have yet to work with a data set that doesn't have any issues-- yet, my colleagues and I have gained much insight into the problems at hand by careful consideration of the limitations of the data. You are clearly out of touch with the realities (and frustrations) of being a practicing scientist Lurgee.

    You are also clearly in denial about the fact that current CO2 levels are the highest in about 800,000 years, and possibly the highest they have been in 15 million years.

    Now to try and focus the discussion back to the topic at hand:

    1) Do you understand that in the past CO2 lagged temperature and why?
    2) Do you understand that the current relationship between CO2 and global temperatures is reversed and why that is?

    I have a suspicion that (deep down) you know the answer to those questions. But if you don't, people here will be happy to give you some pointers or try and explain it to you.
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  50. Anne-Marie Blackburn (@69), you said:
    "This does not mean that CO2 isn't responsible for current warming. Scientists are looking at current data and observations to draw their conclusions, not what may have happened in the past."

    With a little help from scientists at the NCDC I have been trying (in my amateur way) to understand this issue. One would expect to find temperature trends magnified at high latitudes, so I have concentrated on high latitudes in the northern hemisphere. My analysis of Greenland shows a warming trend of >2K since 1850 compared to the IPCC's 0.8K (AR4) for the same time period.

    Given that the CO2 concentration has been rising over this period it is reasonable to suggest that it caused the warming. Here is a plot of temperature anomalies for Greenland's coastal weather stations based on data from the Danish Meteorological Institute (DMI).
    http://diggingintheclay.files.wordpress.com/2010/12/coastal-average.png

    As you will see, there was a rapid rise in temperature that ended in the early 1930s. After that there was a steep decline ending in the early 1990s.

    There must be other factors at work that overwhelm the contribution of CO2 given the 60 year decline during a period when CO2 concentrations were increasing rapidly.
    0 0
    Moderator Response: [Daniel Bailey] GC, do you mean for us to believe that your regional analysis, using DMI data for Greenland coastal stations, is meant to overturn the demonstrated global effects of CO2... Because that's how it sounds...

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