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Global Warming: Trend and Variation

Posted on 7 January 2012 by Tom Curtis

Sit on the beach and watch the tide come in.  You will see some big waves, some small.  The water's edge will advance and recede in a way that is not entirely predictable.  But there is an overall patern that emerges as the hours roll by, and the beach narrows before you.  
 
People get this.  Even the mathematically inept do not scurry to sunbathe higher on the beach if they see a larger wave in a receding tide.  They know the difference between trend and variation.
 
The difference between trend and variation can be found everywhere in our daily lives.  As this video shows, it can even be found so simple a thing as a dog being taken for a walk:
 
(Video by Teddy TV, presenter: Siffer, animator: Ole Christoffer Hager)
 
Although the distinction between trend and variation is as commonplace as an incoming tide, or a dog being taken for a walk; when it comes to climate many people seem to forget it.  They cannot find a temperature graph without seeing a trend each time the variation drifts downwards, and noise each time it goes up.   By doing so, they think they can obscure the long term trend.
 
 
Being fair, in this "dog walk" we cannot see the owner directly.  We can, however, infer his path.  It is as simple as looking for the long term trend.  So, when you try to predict likely future temperatures, are you the sort of person who looks at the dog?  Or the owner?

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Comments 1 to 50 out of 86:

  1. What a great video! Will be a wonderful resource when 'debating' with those who confuse one for the other.
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  2. This is a great analogy. With regard to inferring the path, though, we can do a fair bit better than "looking for the long term trend." The physics tells us where the trend is likely to lie and what may affect it. It's as if we had a note from the owner telling us where he was going on his dog walk, and why.
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  3. Exactly. Long term patterns are important.




    [Source]



    [Source]
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    Moderator Response:

    [JH} Please provide citations for graphics included in your postings.

    [DB] Added patrimony of source graphics.

  4. Pirate: What is your point? In your graph I see a decline for 8,000 years and then for the past 500 years an increasingly steep climb to the highest level recorded in the record. The climb is so steep it is not yet visible in your smoothed average. I note your data does not include the record high year of 2010 (or the previous record of 2005).

    A clear change in trend from declining due to natural variation to increasing due to anthropogenic causes is what we are woried about.
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  5. This video demonstrates the difference between weather and climate in a way that should be understandable to most people. It was made for a Norwegian TV documentary called "Siffer" (meaning digits) about numbers and math that was very popular when it aired on the Norwegian public channel NRK last fall.
    Most of you have probably figured out that "klima" means climate and "vær" means weather.
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  6. apirate unwittingly confirms the urgency of the modern temperature rise relative to the HCO. With an outdated wiki graphic at that.

    Fake-skeptic Fail.
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  7. I'm assuming pirate's showing how AGW is definitely real given the presence of the 2004 arrow in the first graph, unambiguously showing how modern warming is far out of line with the multiproxy mean of the Holocene, even the HCO.
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  8. I believe a pirate's first graph is a product of Dr Robert Rohde who was part of the BEST project.
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  9. The source of pirate's second graphic notes that:

    "This figure shows the Antarctic temperature changes during the last several glacial/interglacial cycles of the present ice age and a comparison to changes in global ice volume. The present day is on the right.

    The first two curves shows local changes in temperature at two sites in Antarctica as derived from deuterium isotopic measurements (δD) on ice cores (EPICA Community Members 2004, Petit et al. 1999). The final plot shows a reconstruction of global ice volume based on δ18O measurements on benthic foraminifera from a composite of globally distributed sediment cores and is scaled to match the scale of fluctuations in Antarctic temperature (Lisiecki and Raymo 2005). Note that changes in global ice volume and changes in Antarctic temperature are highly correlated, so one is a good estimate of the other, but differences in the sediment record do no necessarily reflect differences in paleotemperature. Horizontal lines indicate modern temperatures and ice volume. However, since geological records such as ice cores and sediments represent an average often on the scale of thousands of years, direct comparison to current values can be misleading. Larger, short term variations in ancient climate are not present in the fossil record. Hence the comparison is not comparing like with like and is scientifically invalid. Differences in the alignment of various features reflect dating uncertainty and do not indicate different timing at different sites."


    Although the Antarctic ice cores indeed record local temperatures, which are a poor proxy for global temperatures, the temperature scale is intended to indicate global temperature changes. There is, however, substantial controversy over that scale, with Hansen and Sato, for example, arguing that the glacial preceding the current glacial was only 1 degree C warmer than the current glacial rather than the 2-3 degrees C indicated on the chart.

    The source of his first figure states:

    "The main figure shows eight records of local temperature variability on multi-centennial scales throughout the course of the Holocene, and an average of these (thick dark line). The data are for the period from 10000 BC to 2000 CE, which is from 12000 BP to the present time. The records are plotted with respect to the mid 20th century average temperature, and the global average temperature in 2004 is indicated. An inset plot compares the most recent two millennia of the average to other recent reconstructions. At the far right of this plot it is possible to observe the emergence of climate from the last glacial period of the current ice age. During the Holocene itself, there is general scientific agreement that temperatures on the average have been quite stable compared to fluctuations during the preceding glacial period. The above average curve supports this belief. However, there is a slightly warmer period in the middle which might be identified with the proposed Holocene climatic optimum. The magnitude and nature of this warm event is disputed, and it may have been largely limited to high northern latitudes.
    Because of the limitations of data sampling, each curve in the main plot was smoothed (see methods below) and consequently, this figure can not resolve temperature fluctuations faster than approximately 300 years. Further, while 2004 appears warmer than any other time in the long-term average, and hence might be a sign of global warming, it should also be noted that the 2004 measurement is from a single year (actually the fourth highest on record, see Image:Short Instrumental Temperature Record.png for comparison). It is impossible to know whether similarly large short-term temperature fluctuations may have occurred at other times, but are unresolved by the available resolution. The next 150 years will determine whether the long-term average centered on the present appears anomalous with respect to this plot.

    Since there is no scientific consensus on how to reconstruct global temperature variations during the Holocene, the average shown here should be understood as only a rough, quasi-global approximation to the temperature history of the Holocene. In particular, higher resolution data and better spatial coverage could significantly alter the apparent long-term behavior (see below for further caveats). For another estimate of Holocene temperature fluctuations"


    The sentence which I bolded is worth dwelling on. The proxies displayed show a Northern Hemisphere (3 proxies) and tropical (3 proxies) bias, not to mention a Western hemisphere (5 proxies) bias.

    Names are just names, so not a great deal should be read into this, but it is sobering to think that temperatures have now gone well past the Holocene Climactic Optimum and are continuing to rise.

    It is curious that pirate did not show the third graphic from the same < href="http://commons.wikimedia.org/wiki/File:2000_Year_Temperature_Comparison.png">source:



    The current, and very disturbing long term trend is clear. As noted above by Composer, since 2004 the 1998 (& 2002)record has fallen. It should be noted that that record was also exceeded in 2007 and 2009, although those were not record years because lower than the 2005 (and 2010) record. (Data) None of those records are certain because they all lie within error of each other, but all clearly exceed any record prior to 1998.
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  10. And of course pirate ignores the fact that since 8000 years BP, the mean temperature change was bounded by approximately 1 degree (-0.5 to 0.5C). We're now busting out of that range to potentially dire consequences.

    How anyone with any scientific inclination can look at that graphic and not be concerned is astonishing.
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  11. Another excellent resource for me to link to when I am on a debunking mission at other blogs! Shooting down contrarians like pirate, using sober logic instead of their type of religious dogma, is getting to be like shooting fish in a barrel: there is nowhere for them to hide from the light of reason. Keep up the good work.
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  12. Apart from now defining grey body emitters as the new black and autocorrelation as a trick that drives the trend the denialists are grasping at fictional straws. They then claim that the average temperature of our planet has no meaning? By what measure should we judge? Bert
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  13. Love the video!
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  14. It is interesting to think through what happens

    (1) when the leash is removed.

    The dog's path becomes a random walk with a trend (the owner's path).

    (2) the leash is removed, and the owner is now very drunk and in the dark. Now the man's walk is a trendless random walk, but the dog is still "orbiting" him. Or maybe the man is following the dog, the one who knows better how to get home. Or maybe they are influencing each other, while going home very haphazardly? In this case how can you tell the two walks are correlated? This might be important to test for correlation of temperature and CO2 levels, where both have lots of variability.

    Apparently, you look for a "leash" an error correction mechanism between man and dog by subtracting their paths and seeing if it is non-random. If the man calls the dog, it will change direction. If the man hears the dog barking, he will head in its direction. Such stationary linear combinations of non-stationary random variables is called "cointegration".

    Here is an amuusing introduction:

    A Drunk and her Dog

    I wondered if the technique could be used to check correlation of CO2 and temperature. A standard denialist trope is that correlation between their rise is only coincidence.
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  15. Link in last post does not work. Try this in your browser

    http://www.jstor.org/pss/2685084

    Or Google cointegration drunk woman dog
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  16. Shoyermore @14, making a line red in colour does not make it a link.

    As for the possibility that the owner is drunk, we can subtract from the dogs path the effects of likely distractions. If the owner is drunk as well, the result will still be a random walk. As it happens, it isn't:

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  17. Shoeymore @14 tries desperately to avoid the consequences of accepting this simple and elegant animation...
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  18. When new trends appear to be establishing themselves, we should ask ourselves why? Can we explain it with past effects and cycles? Has a new driver/variable recently been thrown into the mix that appears to explain the new trend?

    Mainstream CO2 warming theory fits well into what would otherwise be more puzzling.
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  19. I think the original source of the images in @3 is the Global Warming Art gallery of Robert A, Rohde, as noted by Rob H @8. The gallery contains a number of images that serve as a useful resource.

    As noted by Tom Curtis @9, the first image in @3 emphasizes an important point, namely, that no single record (e.g., GISP-II ice core) provides an accurate representation of global temperature. Note in particular the wide range of temperatures in the early Holocene among records from different regions. Just because Greenland experienced rapid warming in the past, or the fact that Greenland experienced temperatures in the early Holocene that exceeded temperatures that occur there today, cannot be used as evidence that the entire Earth experienced such rapid warming or warm temperatures.

    Excellent video by Teddy TV.
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  20. skywatcher #17, I accept completely the consequences of this elegant animation. I was just point out possible variations of the scenario, which make it more interesting.

    Tom Curtis #16, I know the subtraction of the paths in the case of cointegration would not be a random walk. That is exactly the point I am making. Is it possible to show that CO2 and temperature rise are cointegrated? PS I gave the link in #15. The problem is the link itself, not me.:)

    Obviously, I did not make myself clear initially.
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  21. Shoyemore @20, it is certainly possible to show that CO2 forcing and temperature rise have been co-integrated over the last 40 years, and more accurately that GHG forcing plus anthropogenic aerosol forcing and temperature rise have been co-integrated over the course of the 20th century. I refer you again to the discussion of Foster and Rahmstorf (2011) where I believe this discussion would more properly belong. (It is not off topic here per se, but a more detailed mathematical discussion is more appropriate in a thread discussing a detailed mathematical treatment.)

    With regard to your attempted link @14, I believe there was a problem with your html code. Your @15 and my @16 where cross posted.
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  22. The point of the graphs I posted were to show the long term patterns and trends as the original post and video showed. Especially the longer graph with it's classic sawtooth pattern shows pretty much the same movements as the video clip. The Earth's temperature oscillates over time in a fairly regular pattern.

    Sure, there are perturbations within the overall movements. Certainly CO2 is a GHG. Certainly human activities affect CO2 levels. But, the overall pattern stays the same.

    And, FWIW the tide on that beach with the cartoon dog is going to ebb. We can't forget that.
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  23. pirate#22,

    Are you conflating forced variation (what you call the 'classic sawtooth pattern' of glacial cycles) with the pseudo-random tendencies of a dog on leash?

    Forced variation is not 'perturbation.' This was about short-term variation on an underlying trend, which has nothing to do with the graphs you post.

    The tide will indeed ebb, because it is driven by the interaction between the moon and the earth. The appropriate analogy here would be: What would the tides look like if we added substantial mass to the moon?
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  24. apiratelooksat50 @22, so your point was to show that "the overall pattern stays the same" in the same way that the overall pattern of CO2 levels has stayed the same:



    Is that right? Or was your point that the overall temperature pattern will stay the same even though humanity have radically altered the level of one of the main forcing agents?
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  25. As pirate has raised the issue of the basis of the saw tooth pattern of the dog's wanderings, the following is the smoothed annual values of the GISS global-land ocean temperature index from 1992 to 2010 for comparison:



    The resemblance to the dog's path is striking. However, no part of the video's logical point depends on that comparison. However, as Muoncounter notes above, comparison of the pattern with forced variations operating over thousands of years entirely misses the point.
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  26. Pirate#22- It is disingenuious to extend the analogy in the manner that you did.For that comparison to hold,there would have to be no other positive forcings in the level of the ocean other than the moon's gravity.Are you denying that CO2 is a positive forcing that is increasing?
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  27. When and why, Pirate, will it ebb? Sometime after humans stop pouring GHGs to the atmosphere? Or in the next 20 years, due to some as-of-yet-undiscovered natural cycle?
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  28. For the lay reader, apiratelooksat50 has a background in teaching science at the high school level in the US, plus a professional career in environmental science. For over a year he has been following an agenda of "It's not happening", "It's not us", "It's not bad".

    Now he has seemingly moved on to the "It's a natural cycle" meme. My take on his most recent comment above is that he has carefully crafted his statement to imply that, since all the previous 'oscillations' of Temps and CO2 showed lockstep integration of peaks & valleys that somehow, mystically, temps will 'drag down' CO2 (because, surely, with his background he cannot be intimating that the well-understood radiative physics of CO2 do not apply to fossil-fuel-derived CO2, can he?)...

    If so, his comment is crafted on presumption. The presumption that CO2, normally acting as a feedback of temperatures, can not also act as a forcing (which it can) on temperatures. Therefore, one can only infer at what the temperature response will eventually be to the rise of CO2 that mankind has caused (the rate of which is higher than anything during the last 255 million years, covering multiple mass extinctions):

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  29. DB,

    pirate's failed 'tides must ebb' analogy actually reveals a wide hole in his defensive line. Tides rise and fall because they must - not because of random perturbations; tides are 'forced.' Temperature rises because it must - it is forced by the physical environment. CO2 is a massive change in that environment. What environmental change does pirate envision - on a time frame comparable with the recent warming - that will force temperatures back down?

    Or have we come back to those 'natural cycles'? An argument as lucid as 'the Great Pumpkin'?
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  30. Pirate: it is still not clear what you are claiming. If you mean that temperature and CO2 are linked, which the data in the graphs you posted supports, then Tom's graph here shows that we should expect a temperature rise of about 12C (!!) from the current CO2 level. How high will it have to go before you are worried?

    Or are you suggesting that the temperature is not linked to CO2 at all and we should expect the previous glacial cycle to continue? Can you provide a cite to support such an extraordinary claim?
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  31. michael sweet @30, you have over interpreted the graph. The temperature indications are for local, Antarctic temperatures, not global temperatures. Daniel Bailey's equivalent graph @28 is scaled for global temperature changes. Further, GHG forcings only represent about 45% of the total forcings going from glacial to interglacial, with the rest coming from albedo changes. Therefore the expected temperature change from the increase in CO2 is well short of of 12 degrees C.
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  32. muoncounter

    Indeed, apiratelooksat50's defense is as porous as that of the Detroit Lions. Basically, the point is to chase the guy with the ball to the end zone repeatedly, with the hopes that he eventually gets tired and stops.

    Essentially the football version of how to catch a knuckleball.
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  33. Muon at 23
    No, I am not conflating the two. I am extending the concept to long term instead of short term.

    In your mind, what is forcing the variation in the sawtooth graph?

    TC at 24
    No to your first paragraph and yes to your second.

    Tmac at 26
    I plainly stated that CO2 is a positive forcing that is increasing.

    DSL at 27
    Do you think there is not a natural cycle? There certainly is one – look at the graph. Humans have only been radically altering the planet for a very short geological time.

    DB at 28
    When the temperature in red begins to match the CO2 in blue, I will concede. It is going to take quite some time before we can say for sure.

    In the meantime we should all be doing the “right” things as I’ve posted before. Including, but not limited to: conservation and developing new energy sources.

    Muon at 29
    The Earth’s temperature certainly rises and falls because it must. CO2 is a player, but not the driver.

    Sweet at 30
    I am saying that CO2 and temperature interact in a complicated way. All you have to do is look at the lag. So, no to the presumption of your last paragraph.
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  34. pirate#33 "I am not conflating the two."

    Conflation: ... the practice of treating two distinct concepts as if they were one does often produce error or misunderstanding, as a fusion of distinct subjects tends to obscure analysis of relationships which are emphasized by contrasts.

    You took an example of pseudo-random variations about a long term trend and an example of forced variations and stated, "it's classic sawtooth pattern shows pretty much the same movements as the video clip." Your words, "pretty much the same" seem to me to treat the two as if they are one.

    Such apples and oranges comparisons are of no value to the teaching of science; in fact, they lead to logical fallacies.

    "Minds, like rivers, can be broad. The broader the river, the shallower it is. Therefore, the broader the mind, the shallower it is."

    As a science teacher, you should be aware of the dangers in modeling this behavior.
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  35. apirate... The "sawtooth pattern" you see in the longer geologic record is actually much more similar to the tide example being used. There is a known forcing causing those changes. With the tide it's the moon orbiting the earth. With the glacial-interglacial cycles it's the rather more complex pattern of Milankovitch cycles.

    What's being explained by the video is the noise over the signal in both of these cases. As the moon "forces" the sea level to rise the noise over the signal is the waves coming in. Some big ones, some small ones, but over time all leading to a rise.

    As orbital factors "force" the climate out of a glacial cycle there is noise over the signal of warming and cooling occurring along the way, but all with a trend toward warming.

    With climate today the "force" is us through our changing the radiative properties of the atmosphere with the burning of fossil fuels. That creates the trend. Within that trend there is the variation. That trend will only change and begin coming down when the forcing changes direction.
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  36. 33, Pirate,
    CO2 is a player, but not the driver.
    This is false, and a mere assertion on your part. We've been over the science on this, and you made no effort to refute it. Do you have a case to make that supports your contention?

    Something that amounts to at least a little more than "gee, this has never happened before, so it can't be happening now"?
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  37. apiratelooksat50 says:
    "When the temperature in red begins to match the CO2 in blue, I will concede."
    It already has begun to do so. Perhaps you missed the graphic Tom Curtis has so thoughtfully provided for edification purposes in Comment 10 above?
    "It is going to take quite some time before we can say for sure."
    Actually, we can tell that it already has. You continue to argue, with no supportive evidence, that "It's Not Us".

    That you repeatedly choose to deny the science, as a science teacher, is both ironic and revealing.

    You are simply trolling now. Everyone: I suggest we no longer continue to feed this troll.
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  38. Muon at 29 and DB at 32
    That's pretty funny. Just make sure you aren't becoming
    this guy.
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  39. OT:

    Very funny song from some Australian chaps: Denial Tango.

    This verse pretty much sums up the denial attitude: "I'm skeptical of everything I just don't wanna know"
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  40. Rob at 35
    The tide rises and ebbs due to the influence of the gravitational forces of the moon. There are other factors involved that create the "noise".

    If we apply that analogy to the temperature/Milankovitch cycle connection then the orbital forcing correlate with the moon's gravity. Other factors along the way are the noise. That would include GHGs.

    Is there definitive proof that the effect of the GHGs is enough to override the orbital factors as we should be heading into another glacial period?

    Thanks for you civil tone and I am willing to listen.
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  41. "Is there definitive proof that the effect of the GHGs is enough to override the orbital factors as we should be heading into another glacial period?"
    That would depend on what your meaning of "definitive proof" is.

    Try Tyrrell 2007 and updated info found in Tyrrell 2011:
    "the next ice age (or the next several ice ages) may be avoided"
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  42. pirate#40: "Other factors along the way are the noise. That would include GHGs."

    A leap of illogic. You must know by now that Milankovitch variations are small and require feedback in order to cause large scale temperature changes. GHGs provide that feedback and hence are not noise.

    "Is there definitive proof that the effect of the GHGs is enough to override the orbital factors"

    The very curve you posted (and seem to think is the key exhibit here) shows just how GHGs amplify - not override - orbital factors. Are you familiar with Caillon et al 2003?

    CO2 is not the forcing that initially drives the climatic system during a deglaciation. Rather, deglaciation is probably initiated by some insolation forcing , which influences first the temperature change in Antarctica (and possibly in part of the Southern Hemisphere) and then the CO2. This sequence of events is still in full
    agreement with the idea that CO2 plays, through its greenhouse effect, a key role in amplifying the initial orbital forcing.


    If you profess to understand the 'CO2 lags temperature' argument (which you seem to find so compelling), you have some homework to do.
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  43. Pirate,

    Continuing the analogy of cyclical climate change as tidal rising & ebbing, GHG increase would translate to adding more volume to the sea. There would be variation along the trend. Sea level would still periodically fall, with the ebb point being, not consistently, higher than the previous rise points.
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  44. apirate.... With glacial-interglacial cycles GHG's work to amplify the signal coming from orbital forcing, as do other things like ice albedo. The noise is just the way the climate responds to those forcing and feedbacks over shorter periods.

    The "definitive proof" is merely physics. We know what atmospheric gases have radiative properties. We have clearly quantified those radiative properties and we can measure the radiative imbalance resulting from increasing GHG concentrations in the atmosphere. That's the settled science. As Stephen Schneider stated in the video I posted a week or so ago, "You can't add 4W/m-2 to the entire surface of the earth and expect nothing will happen."

    The noise is a function of the climate system itself. Climate is complex and it responds in a wide variety of ways whether the forcing is from orbital factors or it's us adding GHG's. The direction of the forcing is clear. The shorter term ups and downs are expected and somewhat unpredictable. The trend is predictable.

    Can you predict how far up the beach each wave will reach? No. Can you predict whether the tide is coming in or going out? Yes. That's basic physics.

    Within the glacial-interglacial cycle can you perfectly model the shorter term noise of warming and cooling? No. Can you model the glacial-interglacial cycles themselves? Yes. It's basic physics.
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  45. apirate... "Is there definitive proof that the effect of the GHGs is enough to override the orbital factors as we should be heading into another glacial period?"

    To more directly answer that question I would have to say that science understands the amount of forcing coming from orbital cycles and those very much pale in comparison to the radiative properties of man-made GHG's. I believe the data is contained within Caillon 2003 that muoncounter linked to.

    This is also discussed in Miller 2010 where they state that orbital factors are actually acting to drive a "neo-glacial" cycle starting about 5000 years ago. What we've done is counteracted that orbital forcing with anthropogenic GHG's.

    The uncertainties outside of "settled science" have to do with other factors. No one here would ever claim that climate science has this locked down. There is always more to know. That we are driving warming is settled science. Exactly how the climate system will respond to that warming is still uncertain.
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  46. "Is there definitive proof that the effect of the GHGs is enough to override the orbital factors as we should be heading into another glacial period?"

    "proof" and science have a difficult relationship. However, since the forcing due to GHG is larger than the forcing due to milankovich, is that arithmetic inequality a good enough proof for you?
    ie maximum milankovich forcing per century at 65N at 0.25W/m2
    cf 1.66W/m2 for CO2 alone for whole globe?
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  47. You might also note that milankovich forcings have always been with us but can only initiate an glacial/interglacial cycle when GHG concentrations are low enough for the ice-albedo feedbacks to be significant.
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  48. pirate @40, it is by no means obvious that we would currently be heading into an ice age even without human generated CO2. Based on modelling, the current milankovitch forcings are such that we would enter an ice age only with CO2 concentrations below 220 ppmv


    Caption:
    "Orbiting the Sun. Long-term variations of eccentricity (top), June insolation at 65°N (middle), and simulated Northern Hemisphere ice volume (increasing downward) (bottom) for 200,000 years before the present to 130,000 from now. Time is negative in the past and positive in the future. For the future, three CO2
    scenarios were used: last glacial-interglacial values (solid line), a human-induced conc entration of 750 ppmv (dashed line), and a constant concentration of 210 ppmv (dotted line).
    "

    (My emphasis. Source, Berger and Loutre 2002)

    As I have argued elsewhere, it is by no means clear that we would have entered an ice age without pre-industrial anthropogenic CO2 emissions, but it is certainly clear that we will no with industrial CO2 emissions. At least, not for the next 50,000 years.

    I would suggest, however, that this topic is off topic for this thread.
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  49. pirate @33, you now claim that:

    1) The overall temperature pattern will stay the same even though humanity have radically altered the level CO2 (from your response to my 24); and

    2) CO2 is a positive forcing that is increasing (from your response to Tmac at 33).

    Given the scale of the CO2 increase relative to normal glacial levels, and the scale of likely future anthropogenic increases in CO2 levels as shown by DB, these claims are only consistent if net feedbacks are negative so that the increase in temperature due to increased CO2 is much less than the 1.2 degree C increase expected from doubling CO2 with no feedbacks. Not only does such a low response fly in the face of all the evidence on climate sensitivity; but it is also inconsistent with such large temperature changes between glacials and interglacials as shown in the chart you presented. That change is almost entirely due to feedbacks on a locally large but globally very small (<< 1 w/m^2) milankovitch forcing, and if feedbacks are net negative, such a large feedback is in fact impossible.

    Consequently your beliefs as presented in this thread (because they are contradictory) are not even rational, let alone based on the scientific evidence.
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  50. Often there is something going on in the minds of 'skeptics' that can explain this sort of behaviour. While they use the label 'skeptic' for themselves which implies a dispassionate bur reasonable doubt, in reality what is actually going on for 'skeptics' is actually something else.

    An actual disbelief in the warming in the face of the evidence.

    Or more importantly perhaps a 'need' to disbelieve; damn the evidence, this CAN'T BE TRUE.

    One of these so called 'skeptics' is actually like someone who is looking for the loose thread that they can tug on to make the whole tapestry unravel. How often do you hear AGW described as a 'house of cards'. What a reassuring image that is to them. Pull the right card out and the house comes tumbling down.

    That whooshing sound you just heard wasn't the sound of cards falling, but rather a huge exhalation of breath. Thank God. This idea that we so desperately needed to make just go away turned out to be 'just a house of cards'. We can all breath a sigh of relief and go back to a life where there aren't any threats, where we all feel safe & comfy.

    Where as the image that AGW is like a jigsaw puzzle is deeply disturbing. If one piece doesn't fit, that doesn't make the whole puzzle wrong. Which is such a terrifying thought.

    Because this is the underlying thing revealed by the most vehement, angry, vicious flavour of 'skepticism' The desperate fearfulness of its adherents. Simple rule in life - when you see Anger, look for the Fear that underlies it.

    So when a 'skeptic' cherry picks a short term trend to say - "see, see, see. Its stopped warming. So much for all your Warmist's theories". Stop and listen for the whoosh; The sense of relief that the fearful feel when they think they have found release from their fear.

    Oh that life were so simple.
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