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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 1 to 50 out of 246:

  1. The lag at the beginning of an interglacial is not overly useful for determining the impact of CO2 on the temperatures. Far more interesting is the end of the interglacials.

    At the end of the Eemian CO2 was above 260 ppm until ~112 kybp. Temperatures had been dropping for more than 10,000 years before the cooling oceans was sufficient to reduce the amount of CO2 in the atmosphere.

    Forget the beginning of the interglacial periods to determine the importance of "warming." The fact that the interglacials end with CO2 already elevated indicates that the forcing effect of CO2 is not the critical factor in the glacial cycles.

    Solar insolation leads the global temperature which leads the CO2 levels both at the beginning and end of the interglacials.
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  2. TIS:
    As the article points out, CO2 was not a forcing in the past. It was a feedback to the solar forcings. CO2 can be both a feedback and a forcing. In the past CO2 was a feedback. The situation today is that CO2 is the forcing. The data showing CO2 lag indicate that the solar forcing started the cycle and the CO2 feedback makes the cycle stronger. Since CO2 is the forcing today its effects are different from what was seen in the past.
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  3. Pity that the chart doesn't show today's CO2 levels. That really puts the cat among the pigeons!
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    Moderator Response: [Daniel Bailey] Try this one then:
  4. TIS says:

    the forcing effect of CO2 is not the critical factor in the glacial cycles.

    Anne-Marie says:

    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.

    Is it my imagination, or has yet another "skeptic" erected yet another strawman?
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  5. Thanks, Daniel. Would you give me permission to use that image elsewhere (with credit to you and skepticalscience.com)?

    It's a very stark reminder of what we're doing.
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    Response: [Daniel Bailey] Not mine to give permission for. However, the SkS version is here. See the Creative Commons language there for fair usage. Thanks!

    [John Cook] I've added CO2 History to our list of Climate Graphics. It's under a Creative Commons licence so you're free to use it elsewhere:

  6. All, If CO2 isn't a significant factor, the concentration that is 400ppm instead of 270 ppm doesn't really matter.

    Phila,
    Is it strawman to point out that elevated CO2 levels in the past existed while the Earth dramatically cooled? According to the Vostok record the temperature dropped 6C while CO2 levels were stable. If elevated CO2 levels caused the warming, then the Earth would not have cooled.

    Or are you simply using strawman as a method of avoiding the data from the end of the Eemian?
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  7. #6: "If CO2 isn't a significant factor... "

    If you've reached that conclusion, you haven't been paying attention. Read the paragraph under Fig. 1 above again.

    "elevated CO2 levels in the past ... "

    The strawman is by your choice of one aspect in a complicated story. Elevated? compared to today, no. Elevated while the earth cooled because of a change in orbital parameters that initially overwhelmed the effect of atmospheric CO2.

    "If elevated CO2 levels caused the warming ... "

    In #1, you asked us to discount the glacial terminations, now here they are as part of your argument. Bad choice, as the literature doesn't support you:

    The overall correlation between our CO2 and CH4 records and the Antarctic isotopic temperature is remarkable (r^2 = 0.71 and 0.73 for CO2 and CH4, respectively). This high correlation indicates that CO2 and CH4 may have contributed to the glacial–interglacial changes over this entire period by amplifying the orbital forcing...
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  8. #6 The Inconvenient Skeptic:

    Is it possible that more than one thing can cause the earth to warm or cool? Is it possible that something else changed while the CO2 concentration was stable during a period when the earth cooled?
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  9. Democracy Now reported Congressman Shimkus of Illinois will be the head of the subcommittee on environment and economy.He said in 2009:Today we have about 388 parts per million in the atmosphere. I think in the age of the dinosaurs, where we had most flora and fauna, we were probably at 4,000 parts per million. There is a theological debate that this is a carbon-starved planet—not too much carbon. Where does he get these ideas??
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  10. "The Inconvenient Skeptic" is simply repeating the stupidity that climate science presumes that *only* CO2 affects climate, and changes in solar insolation does not.

    TIS: climate science doesn't claim that. What you are doing is known as making a "strawman argument".

    The difference between now and the prehistorical times you mention is very simple:

    Back then, fossil fuel wasn't being burned in ever increasing quantities.

    It's so tiring to hear people claim, in essence, that if one burns hydrocarbons, the resulting CO2 doesn't end up in the atmosphere.

    Where do you think it ends up? ( -edit- )
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    Moderator Response: [Daniel Bailey] Be nice. No need for a tactical nuke when a 2x4 will suffice.
  11. Hi

    In the first graph, what year is 'present'?
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    Moderator Response: [Daniel Bailey] It's my understanding that the ice core record graphics typically use 1950 for their "year zero" baseline unless otherwise specified. See the response in comment 3 above for a somewhat updated version.
  12. i am very familiar with this vostok ice core graph and i've always wondered why the 'noise' in our present time appears. i.e. we appear to be stabilized between an interglacial and a glacial and while the chart 'predicts' a glacial we are hovering around our current level of global temperatures. CO2 is continuing to rise as is evidenced by the mauna loa readings but why are our temps stable? is the excess CO2 preventing the next glacial? over the past 400k years we've seen a periodic steep increase in temps followed by a steep temp decrease (glacial) but we have avoided that somehow. why? and why did temps decrease around 130k years ago while CO2 remiained high?
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  13. The tortured logic by Ms. Blackburn and Jeffrey Severinghaus are good examples of the nonsense that surrounds CAGW dogma.

    Cause precedes effect. Get used to it.
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    Moderator Response: [Daniel Bailey] Respectfully, GC, you are quite wrong on the "cause precedes effect" trolling comment you made. We know why conditions were the way they were in the past. Just as we know why conditions are different today, with CO2 acting as a forcing instead of its usual feedback to temps. But being wrong doesn't give you leave to be rude. Find a way to respectfully disagree. Or...
  14. Re: garythompson (12)

    "...why are our temps stable?"

    They are not. They are rising.



    "Is the excess CO2 preventing the next glacial?"

    Looks that way. See here.

    "Over the past 400k years we've seen a periodic steep increase in temps followed by a steep temp decrease (glacial) but we have avoided that somehow. why?"

    Interglacial length/duration does have some variably associated with it, but all signs were pointing to a long (on a human scale, not a geologic scale), slow decline into a resumption of the current ice age. Until mankind intervened with its fossil fuel CO2 emissions.

    "Why did temps decrease around 130k years ago while CO2 remiained high?"

    In times previous to our civilization, CO2 acted as a feedback to temps. When orbital conditions caused a warming of temps, warming oceans outgassed more CO2, enhancing the natural warming going on (hence the quick rise out of glacial conditions into interglacials). Then, as orbital conditions changed, temperatures fell. CO2 lagged behind temps because sequestration of CO2 is a slow process, requiring tens of thousands of years. CO2 concentrations now have risen so quickly that CO2 is acting as a forcing to climate, causing the global temps to rise, which in turn cause other feedbacks to kick in, which in turn causes CO2 levels to rise further. Manmade CO2 concentrations are the big driver here, though. Gross 30 billion tons, of which the environment manages to do with about half (causing other issues, like ocean acidification), for a net increase of about 15 billion tons per year. Or about a 2 PPM yearly increase in atmospheric concentrations (the rate of increase itself is also increasing).

    Hope this helps,

    The Yooper
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  15. @ Garythompson

    "and why did temps decrease around 130k years ago while CO2 remiained high?"

    I'm a rank amateur, but I'd question the accuracy of the ice core on that point. They measure CO2 levels from air bubbles trapped in ice. There's always going to be a margin of error in that, because the air bubbles will be formed in older snow, and it's doubtful how accurately thousands of years of variation can be recorded in a few metres of ice. Also, looking at a single ice core is a bit like looking at a single thermometer - you can't really be sure how much is local variation, how much is global, and how much is just confusion and noise.
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  16. The Inconvenient Skeptic #1 & #6

    John

    Sorry to have not continued our discussion recently - technology problems have kept me off the air. Currently I am sitting in a cafe writing this.

    "If CO2 isn't a significant factor, the concentration that is 400ppm instead of 270 ppm doesn't really matter.....According to the Vostok record the temperature dropped 6C while CO2 levels were stable. If elevated CO2 levels caused the warming, then the Earth would not have cooled."

    We have had this discussion before John and I pointed out the fallacy of your reasoning then. You are comparing ppm levels and using language like 'significant factor', 'CO2 levels caused the warming'. Your argument is based on imprecise use of language and failing to compare forcings quantitatively. Multiple factors influence the progression through Ice Age cycles - Orbital changes, Methane, CO2, Albedo change due to ice sheet variations, Albedo change due to changes in vegetation patterns etc

    Many of these factors can be estimated and quantified and they support this general understanding. CO2 is one factor that mattered then, but not the only one. As I have pointed out in an early discussion we had, when there are multiple factors, not all of them may be forcing in the same direction. As I pointed out to you, during the Holocene CO2 levels only varied by about 20 ppm until recent times. Milankovitch was stronger. How NET forcing varies depends on the sum of all of them. CO2 can remain stable, or even rise somewhat such as during the Holocene, but if other forcings are working against it then they can dominate.

    Not because CO2's impact is small, period. But because it's impact is only one part of all the impacts in THAT context. In a different context such as today, its percentage contribution is different. Understand CO2's quantitative impact in one context so we can calculate its quantitaive impact in a different context.

    You mention the Eemian, the exit from an inter-glacial before our current one. We have also discussed the behaviour over the Holocene. If you want to argue about what 'the data' tells us then you need to provide the data that matters. Not simply the temp vs atmospheric level figures for CO2. Rather the Temp vs Forcing data for multiple factors. The relative forcing associated with these various factors and thus their relative significance. Not every Milankovitch cycle is the same so the magnitude of the forcing variation varies from cycle to cycle. Similarly you aren't discussing changes in Methane levels. Also, look at the first figure shown by Anne Marie. The CO2-Temp relationship is different for each one. Because each cycle has different particular circumstances.

    In your posts you are also repeating something I have pointed out to you before, a failure to distinguish between the significance of what a 'level' means, and the significance of what a 'change of level' means. This comment 'If elevated CO2 levels caused the warming, then the Earth would not have cooled.'! Whether they are elevated or not isn't the point. It is change in the level that matters in producuing a forcing. And even then this goes into the mix of other factors that can all produce forcings. If CO2 behaved in the past in ways consistant with our understanding of its behaviour, then we can project that behaviour onto what we expect to see today.

    If you feel that the Ice Core record casts doubt on this, show us the calculations. Show us some calculations of forcing changes over the Ice Core record for Milankovitch, CO2, Methane, Albedo etc. Show that CO2's behaviour from that record is inconsistent with what we expect from current radiative physics.

    You are an engineer John, but much of what you have argued here and on your blog uses qualitative arguments. Put some meat on the bones of your argument. Do the math. Show us how the forcings change and that CO2's contribution doesn't match expectations

    "Or are you simply using strawman as a method of avoiding the data from the end of the Eemian?" No John, they pointed out the strawman in your claim which is fundamentally a mis-statement of what CO2's effect is 'expected' to be. A Strawman Argument is about creating a false expectation that can then be 'knocked down'.
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  17. garythompson

    See some of my comments to TIS. The behaviour at different stages of a glacial cycle can be complex and differ from cycle to cycle. For example, starting at the bottom of a cycle, ice sheet retreat is an important factor, replacing reflective ice with darker land and ocean. However retreat for huge ice sheets takes a long and depends on the extent of the ice sheets in different parts of the world, the underlying topography as they retreat etc. So ice sheet retreat is likely to be a slow, lagging forcing.

    Conversely, coming out of an Inter-Glacial, as things start to cool, a wider extent of snow fall can also have a big impact - a thin layer of snow has similar reflectivity to a massive ice sheet. So as some cooling progresses, expansion of snow cover can be a rapid cooling forcing, not a slo lagging one. So the behaviour of ice is potentially a major factor in the difference between the warming and cooling cycles.
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  18. Of course, Congressman Shimkus ignores a few critical issues. First is that that, when CO2 levels were at their highest, the bulk of all fauna & flora was still *Beneath* the Ocean. Second, the plant & animal life that did exist on land during these eras had evolved-over *millions* of years to be able to thrive in a higher CO2, higher temperature paradigm. Third, that the shape of our land-masses & oceans was significantly different to those today-& that must be taken into account when considering whether high CO2 levels today will have a damaging impact on our planet. Still, good to see the usual flimsy "logic" coming out of the so-called skeptic camp.
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  19. Gary Thompson, to the best of my knowledge, the next glacial period isn't due for several *thousand* years, possibly even more than 10,000 years-so your claim is without foundation. As others have already pointed out, why do people like yourself still running around claiming temperatures are "stable", when even a brief analysis shows that they're rising with unprecedented speeds (+0.12 degrees per decade since 1950, & +0.16 degrees per decade since 1980)-with no indication of a slowdown. I do wish people would try & get their *basic* facts right before posting on these boards.
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  20. @galloping camel #13

    Really? Sure, the patient didn't die from gangrene because he rotted mostly after he had died.
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  21. Polar Bear @ 9 Shimkus of Illinois............I think in the age of the dinosaurs, where we had most flora and fauna......

    Well perhaps not.



    Where does he (Shimkus) get these ideas??

    I have a hypothesis, but the comments policy precludes me from elaborating further.
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  22. galloping camel@13 said:

    "Cause precedes effect. Get used to it."

    However complexity and time, can create different causes and switch a cause around to an effect and visa versa.

    It is naive to assume that a cause at one point in time, will still be a cause at another point in time. Ironically it is usually skeptics that emphasise the fact that we have a complex system to analyse, yet bury that philosophy when wanting a simple answer that fits their perspective.

    In fact, the change in materials and processes from causing an effect, to being the effect of a cause is probably employed in many inventions that benefit humanity.
    The cycle of the internal combustion engine comes to mind, or a jet engine, they both depend on a cycle in which a cause, produces an effect which then becomes a cause for the next effect and so on until the original cause finally becomes an effect.

    When a problem occurs in the cycle of causes and effects, the machines operation changes or stops completely.

    In a simple world, you have a cause and that produces an effect, end of story. We don't live in a simple world.
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  23. The complexity of the climate system actually makes it simple: CO2 increases have less ultimate temperature feedback than during the glacial to interglacial time. IOW, as the temperate zones thaw, the earth warms through both CO2 -> temperature and temperature -> WV -> temperature. The effect of more CO2 in the current climate is CO2 -> temperature (with temperature -> WV being much weaker now than during glacial periods).
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  24. #13: "Cause precedes effect."

    Anyone who's argument lives by this, dies by this. Cause: burning fossil fuels. Effect: increased atmospheric GHG and the resultant warming.
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  25. gallopingcamel

    That said, I persist in my minority (at least on this blog) view that in matters of science, cause precedes effect. Therefore, the hypothesis that rising temperatures cause CO2 concentrations in the atmosphere to rise is more plausible than the reverse over the periods covered by ice core data.


    Unless I'm mistaken and missing your point, this is what I said in my OP. I then took it a step further by saying that increasing CO2 levels cause further warming which again releases more CO2 - i.e. increasing CO2 levels become the cause and effect of further warming.

    I have a general objection to "Climate Science". Researchers with hypotheses linking climate catastrophe to the actions of mankind are likely to be showered with money by governments around the world. Scientists who have opposing views are marginalized and de-funded. I call this the "New Lysenkoism" and it is more dangerous than Stalin's version.


    Do you have any evidence to support this? Any evidence that sceptic scientists have lost funding? How do you then explain contrarians such as Lindzen, Spencer and Soon publishing in the scientific literature?
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  26. @lurgee

    ... it's doubtful how accurately thousands of years of variation can be recorded in a few metres of ice ...

    You're right - it actually can be a problem. I recommend the discussion here. I warn You - it is very long.

    CO2 is not correlated with the temperature - at the time - also in the Holocene and the Historic Time (Anno Domini). It was found from 50 (Frank et al., 2010.: “... with a 50-year CO2 response lag—such timing is consistent with modelled CO2 response to a temperature step change.”); to 250 years difference.
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  27. gallopingcamel,
    cause precedes effect

    Of course it does.

    Do you also insist that every effect can have exactly one and only one cause?

    Do you also insist that every cause can produce exactly one and only one effect?

    Do you also insist that a cause can never be the effect of something else, and an effect can never cause anything else?

    Or is it possible that the world is a complex place, and that to resolve situations one must use intelligence and difficult thought, and consider more intricate processes than the merely childishly simplistic?

    Part of what I take from your comments is that you either did not bother to read or simply did not understand the original post. You need to go back and try again, with a skeptical point of view (i.e. not with the mindset of one who already knows that what he hasn't read is wrong, and therefore has no need to focus on what is actually written).

    Your own logic equates to "my father died of cancer, therefore I will die of cancer, therefore I am invincible to everything but cancer."

    You need to study the situation much more intensely if you are to have a viable opinion on the subject.
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  28. lugree,
    I'm a rank amateur, but I'd question the accuracy of the ice core...

    The subject of interpreting ice cores (or any such proxy data) is far more complex than your brief description implies. More importantly, the people that work with them are very, very, very smart, and have spent much of their professional careers dedicated to the subject, not just a few minutes while reading a blog.

    So you have two choices. You can just accept what the experts say, or you can study intently to understand what you are talking about. The third alternative, which is to simply say "I'm a rank amateur, but..." is not an option. That's a cop out. You can't have a strong opinion about something that you admittedly don't understand.

    A very simple starting point: Wikipedia

    Unless and until you at least get through that, you are unjustified in casting aspersions on the validity of the data.
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  29. Rob Painting @ 21:
    I'm not supporting anyone's stance, but it should be pointed out that there is a difference between BIODIVERSITY and BIOMASS.

    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 have a clue about the biomass at that time, but your chart is not applicable.
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  30. I teach environmental science and my students long ago picked up on the CO2 lag. (I know we are talking about high school kids, but oftentimes a simpler, uncluttered insight is valuable. Kind of like Occam's Razor). When they initially saw the chart, their consensus was "that something else is affecting both".

    Now that this article supports the initiation of the warming phase by changes in orbital cycles, their next question is: "Why can't the cooling phase be initated by changes in orbital cycles?"

    This is not skepticism on their part, but inquiry.
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  31. #24 gallopingcamel, I'm not sure what you are accomplishing here. You apologized for being rude, but then proceeded to another completely off-topic generalization (research money). You did not support your cause-effect claim in any way, just repeated it.

    You appear to be ignoring the simple fact that nobody here disagrees that warming causes increases in CO2.
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  32. apiratelooksat50
    Why can't the cooling phase be initated by changes in orbital cycles?

    I'm not sure what your point is. This statement is of course true. The glacials (cold) and interglacials (warm) are both initiated by changes in orbital forcings. Those orbital changes are not, however, enough to cause the changes seen. Something else (CO2) needs to play a major role.

    Interestingly, too, contrary to the overly simplistic view that most people take, the orbital change isn't one of "warmer" or "cooler" for the planet as a whole. That is fairly constant. What actually happens to initiate a glacial period is that northern hemisphere summers change in a way to become cooler and shorter, so that the previous winter's snow and ice extent (in the northern hemisphere) doesn't have the time or energy to melt back. This changes the planet's albedo, reflecting back more sunlight, and that is what makes the planet cooler.

    But not enough to actually cause a glacial. For that, something else has to happen.
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  33. #34 Are you saying that changes, like entering or exiting ice-ages, are kind of interlocking auto-catalytic & feed-back loops, rather than simple "cause precedes effect" type changes?

    Well I'll be!
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  34. thanks so much to many for your replies to my questions in #12.

    to reply to Marcus #19, let me clarify by what i meant by 'temps stable'. i'm not attempting to go OT here and talk about weather stations, GISS data, etc. i was sticking to the graph in figure 1 of this post. if you look at the temperature line, for about the last 10,000 years our temperatures have seemed to be in a noisy region and while it is oscillating, it appears to be flat and uncharacteristic of anything else over the past 400,000 years of this ice core data. why is that? to me, it's the most obvious feature of this graph and everytime i see it i ask that same question.

    oh, one more. the temperature axis is in units of temperature change (C). What is the base period that it uses for the zero change?

    and i second some of the comments stating that ice core data might have some issues with accuracy. i have the same reservations with tree ring data as well. maybe it is my ignorance in how these tree rings and ice cores are extracted, measured and then how these measurements are translated into degrees C and ppm CO2. if anyone has a good source for that i'd enjoy reading that.
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  35. #35, les,
    ...rather than simple "cause precedes effect" type changes?

    Let's have some fun, and look at all of the causes and effects:

    • Multiple orbital changes (orbital shape and inclination, axial tilt and precession, apsidal precession) occur in just the right combinations.

    • These alter the length/strength of the northern hemisphere summer past a tipping point.

    • Winter snow/ice cover on the northern continents does not melt back far enough during the summer.

    • The northern hemisphere albedo changes, reflecting more sunlight back into space, cooling the planet.

    • Atmospheric CO2 is absorbed by the cooling ocean, reducing the GHG effect, and cooling the planet.

    • The snow/ice melts even less.

    • The albedo increases further, and the planet cools more.

    • Even more CO2 is absorbed by the ocean (and, I've always presumed, more vegetation is covered with snow/ice without a chance to decay and return to the atmosphere), cooling the planet even more.

    • With the drop in global temperatures, atmospheric H2O also drops, further reducing the GHG effect.

    • The planet cools even more.

    • The cycle continues -- cooling -- more ice, higher albedo, less CO2, less H2O -- more cooling.

    • Eventually, the expanding snow/ice extent reaches a latitude where summers are simply too long/warm for it to remain, and the process halts -- in a new glacial period that will last until the orbital forcings alter again, to run the entire "program" in reverse.


    How very simple!
    Well I'll be!

    :)
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  36. So, Sphaerica @ #34, I think we agree. Orbital changes can initiate global cooling or warming, but other complex factors (too many to list) affect the rate, intensity and duration of these changes.
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  37. 38, apiratelookat50,
    (too many to list)

    Well, not really... :) See post 37.
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  38. @gallopingcamel #24

    So you had a speech to give. That speech includes truisms like "causes precedes effects", pseudo-categorical assertions about truisms like "in matters of science, cause precedes effect" and an absurd intent of malicious propaganda on your part like "I persist in my minority (at least on this blog) view that in matters of science, cause precedes effect." which implies that the majority here think something along "effect precedes causes" or "I don't care" or "I dunno". This propaganda is a ridiculous pursue, as this is written -you seem to have forgotten that- and everybody's comments -and backgrounds- are here to see. You have just written something that -said perhaps aloud with projected voice and in the absence of recorders- may have an effect on audiences sensible to those kind of verbal sedatives.

    Contrary to most people here, I don't think you are willing to follow any argumentation and provide proper critic. You have some designed messages to sow (they don't get money ... in comparison, Stalin was Mother Theresa) and nothing but such kind of messages to sow.
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  39. 36, garythompson,
    ...maybe it is my ignorance...

    As I said to Lurgee, this isn't acceptable. You can accept what the experts say, or you can study it enough to know the difference. It's unacceptable to simply say "I don't know myself, but I think they might be wrong."

    One of the things that bugs me to no end is the presumption that scientists are stupid, that a layman sort of wandering around a blog in "just thinking things through, using, you know, common sense" is going to come up with all of these ideas that were maybe missed by scientists who studied for decades to earn their degree of knowledge and proficiency, and who now as a profession focus on the topic for eight or more hours a day, five or more days a week.

    ...if anyone has a good source for that i'd enjoy reading that.


    Now that's the right attitude! Simple place to start is here, at Skeptical Science -- Tree Ring Proxies. If you have the time and the background, you can get a lot more detail from this study.

    In general, though, the Internet is a vast and intriguing place. A little bit of searching will find a lot of information -- as long as you're smart enough not to take it at face value, and to realize that any old schmuck can publish his opinions as fact on the Internet.

    Be wary of sneering skeptics, and always check the quality of the source information. If possible, look for independent confirmation (which is not the same as just finding the same lie repeated over and over on the multiple sites with an agenda to push).

    But it's all there to be had, right at your fingertips.
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  40. gallopingcamel at 17:09 PM on 5 January, 2011
    The tortured logic by Ms. Blackburn and Jeffrey Severinghaus are good examples of the nonsense that surrounds CAGW dogma.


    Jeff Severinghaus is a full professor at the Scripps Institution of Oceanography. He is one of Scripps' leading scientists. The Scripps Institution of Oceanography, BTW, is that little place that was recently rated as first in quality nationwide for doctoral programs in meteorology, oceanography, and atmospheric science by no less than the National Academy of Science (linky here: http://scrippsnews.ucsd.edu/Releases/?releaseID=1114, doubters are free to track down the original NAS/NRC report with a bit of googling).

    Someone who dismisses Dr. Severinhaus' work as "tortured logic" and "nonsense that surrounds AGW dogma" truly is taking Dunning-Kruger to the next level.
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  41. gallopingcamel:

    I have a general objection to "Climate Science".

    Frankly, this statement strongly suggests that you are someone who should not be taken seriously. The way to overcome this impression is not to continue posting witless conspiracy theories and snide generalities about "science," but to read articles like Anne-Marie's more carefully, educate yourself where necessary, and offer logical, evidence-based rebuttals to specific points instead of slandering an entire scientific discipline.

    In short, don't proceed from the assumption that everyone's wrong and proving it is a simple matter of throwing enough mud at strangers. Instead, please consider the far more likely possibility that it is you, rather than the world's climate scientists, who are failing to make an intelligent, informed assessment of the evidence. Doing so will put you in a better position to make thoughtful counterarguments to specific claims, or to debate the proper course of action. Wallowing in situational ad hominem, as you've been doing here, simply makes you look like a fool.
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  42. Dr. Richard Alley has a nice rebuttal to those who like to parrot "Cause precedes effect. Get used to it." in any discussion about CO2's role in glacial/interglacial transitions.

    Go to http://www.agu.org/meetings/fm09/lectures/lecture_videos/A23A.shtml

    First, watch the segment at 03:45-05:00; then skip ahead and watch the 34:50-38:50 (approx) segment. Case closed.
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  43. 1. Does anyone have a source for a chart showing the other greenhouse gases and their relationship with the temperature cycle?

    2. The sole focus on CO2 (and anthropogenic CO2 at that!) troubles me. Does anyone have a valid reason for the focus on CO2?
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  44. Sphaerica:

    One of the things that bugs me to no end is the presumption that scientists are stupid, that a layman sort of wandering around a blog in "just thinking things through, using, you know, common sense" is going to come up with all of these ideas that were maybe missed by scientists who studied for decades to earn their degree of knowledge and proficiency, and who now as a profession focus on the topic for eight or more hours a day, five or more days a week.

    Ditto. As one of my teachers said, "If you're getting results that challenge the scientific consensus, there are two possibilities: You're a genius who's going to win the Nobel Prize, or you made a mistake somewhere."

    It seems like a lot of "skeptics" would respond to this statement by running out and buying a tuxedo.
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  45. apiratelooksat50

    The reason this article focused on CO2 specifically is down to the fact that it directly addresses the argument by contrarians that CO2 cannot be driving current global warming as it didn't drive global warming in the past 400,000 years or so.

    In general, the focus is not solely on CO2. CO2 remains the main focus as it has the greatest impact on radiative forcing of all other factors. But factors such as black carbon, changes in albedo, solar variability and volcanic activity are also considered in the overall picture. Have a look at chapter 2 of the IPCC's scientific report for more information.
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  46. apiratelooksat50 @43:

    The sole focus on CO2 (and anthropogenic CO2 at that!) troubles me.

    Regarding the "sole focus" misconception, please see CO2 is not the only driver of climate. Regarding the "anthropogenic CO2" comment, the simplest explanation is that anthropogenic CO2 is significant because it's rising dramatically, and natural CO2 isn't. For more details, please see Human CO2 is a tiny % of CO2 emissions.

    Does anyone have a valid reason for the focus on CO2?

    1) CO2 is a greenhouse gas; 2) CO2 levels are rising due to human activity; 3) We are observing the warming we'd expect given 1 and 2.
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  47. Glenn Tamblyn @16,17 - Thank you for this. A lot of time is spent arguing the minutia of various bits of Climate Science, having it put back together in a coherent whole helps keep it in perspective.

    Philia @44 (and Spherica quoted) - A great summary of the contrarian method and mindset. Enough dusty tuxs to open up a rental shop.
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  48. Since the glacial cycle is a big topic now, it seems to me that the varying temperature slope pre- and post-glacial is an important aspect that doesn't get much attention. It warms up going into an interglacial much faster than it cools when leaving it, in the last few cycles.

    Since the triggering process of orbital variations presumably has the same forcing gradient on both sides, doesn't this imply that the Milankovitch cycles couldn't possibly be the sole cause of the cycles, and that positive feedback is a requirement. And also that positive feedback is much stronger on warming than on cooling?

    I point this out and ask about it because it seems that the more scientifically-oriented skeptics these days focus on sensitivity and claim that there is little or no evidence of positive feedback. The above seems to indicate that belief in strong negative feedback from clouds is misplaced and hard to support. Unless the feedback part of the process works completely different now than in the glacial cycles (due to a different trigger). Is there a reason to suggest that?
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    Moderator Response: [Daniel Bailey] Google clathrate gun hypothesis.
  49. 43, apiratelooksat50,
    The sole focus on CO2 (and anthropogenic CO2 at that!) troubles me. Does anyone have a valid reason for the focus on CO2?

    I have a hard time believing that you teach environmental science, even at the high school level. This is pretty basic stuff.

    That said... there is no "sole focus" on CO2, and there's no need to qualify "anthropogenic CO2" as if it's a different animal.

    As far as "sole focus" goes, no, scientists have studied myriad different climate influences, from changes in insolation to GCRs to land use to greenhouse gases and more. These have been studied through observation and statistical analysis (i.e. "is there a correlation") as well as logic (i.e. "if A causes B, and there is more A, then there should be more B").

    All of these studies have arrived at bupkis as far as evidence, either empirical or logical, for marked contribution to the current warming, except for CO2. In addition, it would be a very surprising result if we were not seeing warming from CO2. That would require lots and lots of research funding, because it wouldn't make any sense.

    As far as anthropogenic versus other "types" of CO2... CO2 is CO2. It's merely a question of what is causing CO2 levels to rise, and that is unquestionably the result of burning huge quantities of fossil fuels (i.e. carbon that has been sequestered under the ground for hundreds of millions of years, with no way until now to get out).

    So, no "sole" focus, and no "anthropogenic" form of CO2.

    In fact, your entire statement reeks of a denier trying to color things in a certain way, rather than that of a person truly looking for education.
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  50. 43, apriatelooksat50,
    Does anyone have a source for a chart showing the other greenhouse gases and their relationship with the temperature cycle?

    First problem, what is "the temperature cycle?" No such thing. You mean "relationship with global temperatures," period, no "cycle."

    Beyond this, there are several ways to look at this.

    The first way to look at it is relative strength as a greenhouse gas, molecule for molecule, and that in itself is an oversimplification. A molecule will absorb (and emit) energy in varying wavelengths, based on its geometry, and that has to be taken into consideration when looking at the absorption/emission profile of the body in question (i.e the Earth). You have to study molecular physics to understand that. There aren't really any simple numbers (this is twice as strong as that).

    The second way to look at it is their relative prevalence in the atmosphere. The most common by a mile, and from that point of view the "strongest," is H2O. CO2 is pretty much next. Methane, CH4, is molecule for molecule a "strong" greenhouse gas, but there's a lot less of it.

    The third way to look at it is the way they get there, and how long they stay. If there's no ready source, or if they don't hang around, any effects on global temperatures would be transient. H2O is the most common, but it's also the most malleable, in that it's prevalence should be pretty directly tied to temperature. As temperatures go up, H2O goes up, and temperatures go up further. As they go down, H2O goes down, and temperatures drop further.

    CH4 is in short supply partly because its residence time in the atmosphere is short... when it gets there, it doesn't stay there long. So it's not going to be that big of a danger in the long term.

    The thing about CO2 is that once it gets into the atmosphere, it takes a long time to "fall out." It mixes well, and the greatest sink -- the ocean -- is temperature dependent. The higher the temperature of the ocean, the less CO2 it absorbs from the atmosphere (or, to put it another way, the more CO2 it releases into the atmosphere, depending on the balance at the time).
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