A Few Things Ill Considered

A layman's take on the science of Global Warming featuring a guide on How to Talk to a Climate Sceptic.

Tuesday, January 17, 2006

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Climate is Always Changing

(Part of the How to Talk to a Climate Sceptic guide)

This article has moved to ScienceBlogs

It has also been updated and this page is still here only to preserve the original comment thread. Please visit A Few Things Ill Considered there. You may also like to view Painting With Water, Coby Beck's original fine art photography.

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18 Comments:

  • At March 17, 2006 5:12 PM, Anonymous Alexi Tekhasski said…

    You say: "The present day climate change is very well understood and is different"... I thought that your bolg was designed to defend this "well understood" position against those many who find that all your "answers" are full of logical holes, therefore the effect is hardly "well understood".

    Then you continue: "Simply noting that something happened before without humans does not in any logical way show that humans are not causing it today". Your construct your line of reasoning on a premise that "climate has varied in the past ... for many different reasons", and therfore you deny any fundamental and persistent physical reason behind historical climate changes. You point now is that human are just another reason for climate change. Your presumption of "many reasons" can be (and likely is) completely false.

    Then you mention that "cause for that cycle [130ky] is fairly well understood to be the results of changes in the orbit of the Earth. These cycles are well understood." This statement of yours is in complete contradiction to facts and scientific opinions, since the very same article, just few paragraphs above your citation,

    http://en.wikipedia.org/wiki/Milankovitch_cycles#100_ky_problem

    states completely opposite:
    "...eccentricity variations have a significantly smaller impact on solar forcing than precession or obliquity and hence might be expected to produce the weakest effects. However, observations show that during the last 1 million years, the strongest climate signal is the 100,000 year cycle", and "Observations show climate behaviour is much more intense than the calculated variations", and
    "...No reason for this change has been established", etc.

    Then you proceed: "The other important difference between the glacial-interglacial cycles and today is the rapidity of the current change".
    As it has been noted elsewhere, the historical data are effectively integrated (=averaged) over several hundred years, so the actual amplitude of past spikes cannot be determined. The data, even after historical averaging, are not smooth, and still are very spikey, which indicates that original concentrations could easily be ten or more times higher then the averages. Therefore there is no data to compare current detailed observations with, and your statement cannot be supported by the data you mention.

    Regarding your concerns about catastrophes to biosphere: since the climate in known to catasrtophically swing between ice ages and warm ages, the part of biosphere that was not fit to adapt to these changes has only one way - to die. I don't think that my kids have less survival skills than dinosaurs, therefore I see no reason to worry about that sort of changes.

    As you can see, none of your arguments are valid.

     
  • At March 17, 2006 6:17 PM, Blogger coby said…

    Re the purpose of the blog: no, it is meant to provide the simple and solid answers to the ignorance and illogic that passes for scepticism in this politically motivated debate. The fact that people who *don't want* to understand do not understand is no reflection on how well understood things are by knowledgable, intelligent and honest people.

    Your second paragraph is non-sensical as written. But, you are the one who denies there are any deterministic physical mechanisms influencing the climate, not I. A large CO2 pulse is the primary physical mechanism behind today's change, past changes have had different causes some well understood, some less so. This article addresses the simple logical fallacy that climate change has happened without human influence, therefore this climate change is not human influenced.

    Re: Milankovich cycles, the article should read "These orbital cycles are well understood". You are correct that there are still some problems getting the modeled effects of those cycles ("well understood") to match the observed response ("fairly well understood"). No one ever said there is no work left to be done.

    Yes, the ice cores don't resolve decadal fluctuations, but can you provide any reason to expect the kind of huge flucuations you fantasize about above, besides the fact that it is not impossible based on this data alone? There is no evidence in any other records where such resolution is possible of the kind of enormous flucuations you are postulating. The proxy reconstructions of the past 1 and 2 thousands years also lend weight to the notion that the current global climate change is not normal in its rapidity.

    The large swings between glacial and interglacial climates are an order of magnitude slower than the current change. Google "Paleocene Eocene Thermal Maximum" for an historic analogue to today's potential catastrophy.

    As you can see, all of my arguments still stand.

     
  • At March 18, 2006 4:51 PM, Anonymous Alexi Tekhasski said…

    No, your arguments fail. Try to average current CO2 data over 500 years, and see what you will get.

    About Milankovich 100ky cycles, I repeat: "Observations show climate behaviour is much more intense than the calculated variations". Translation: intense climate behavior have no current explanation within simplistic theory of climate forcing. "Much more intense than calculated" does not fit the definition of "fairly well understood", sorry.

     
  • At March 18, 2006 5:34 PM, Blogger coby said…

    Let's take that average from now until 500 years from now instead, then see it it would show up. Anyway, by what mechanism to you propose CO2 was injected into the atmosphere so suddenly and absorbed so quickly that it is not resolvable in the ice cores?

    You might want to check into some of the recent research into the PETM and note that that disturbance, comparable to where we are heading, lasted about 100K yrs.

    The orbital forcings of the glacial interglacials were small but amplified by ice albedo feedbacks and GHG feedbacks and I believe the models can come close to approximating most aspects of those cycles. The wiki article is not very clear, and if it says what you take it to mean, I don't think it is correct.

    Still standing.

     
  • At March 18, 2006 11:06 PM, Anonymous Alexi Tekhasski said…

    I think I am not explainig this clearly. Say, you have the following yearly concentrations of CO2 (in some arbitrary units) with "unprecedented" 1000% jump in one year, from 1 to 11:

    1,2,1,1,2,3,1,1,11,13,12,10,11,10,11..

    Then the data bins were sitting in a stack for 400,000 years, so each concentration gets diffused into neigbouring bin, say, over a distance of 2-3 bins, both ways, so each bin is a running average over five years. The result is:
    1.4, 1.8, 1.6, 1.6, 3.6, 5.8, 7.6, 9.4, 11.4, 11.2, 10.8.....

    As you see, now the biggest jump is only 60%, from 3.6 to 5.8, or 5 times smaller than the original jump from 1 to 11. I hope you now get the idea why the data averaged over 1000 years may have the spikes and jumps well concealed (actual CO2 records have the average time resolution of 1460 years BTW). Corollary: you cannot derive any conclusion how precedented or unprecedented is the current jump in CO2 concentration based on ice core data.

    About orbital forcing: fine, small differences in insolation were amplified by ice albedo feedbacks and GHG feedbacks (on the way down I guess), but then what? Some flip-flop happens, so the ice age gets abruptly terminated, for unknown reasons. Right? Is this what do you call "well understood" and "most aspects"? And how we are supposed to handle all this hand waiving, "feedback here, feedback there.."? Which model came close to reproduce abrupt glacial terminations?

    So, we obviously have to sit down, write a time differential for every essential component of climate, equate it to corresponding in and out fluxes ("feedbacks"), add nonlinear interaction to ensure "boundness", and... Guess what will we get as a starting point? Maybe this?
    http://www.copernicus.org/EGU/npg/12/npg-12-311.pdf

    Therefore, we are back to the original concern: does the Earth climate need different reasons every time it "changes"? Is the antropogenic influence really that reason this time? Or maybe the climate oscillates by itself, and the small insolation periodicity is just a pacemaker? I guess the politically-aggressive climatologists and their apologists need to work harder, learn some modern mathematics, to understand the real nature of climate.

     
  • At March 19, 2006 6:13 PM, Blogger coby said…

    Thanks for the number series, it is useful. I understood that to be the effect you were talking about and I agree it is an apt analogy. I would like to interject that "the devil is in the details" and there are many other indicators and clues so I don't know if it is as straightforward as you have it illustrated, paleoclimatologists may be able to infer a bit more (or a bit less, I don't know). I suggest reading the relevant papers for details, the IPCC report would be a good starting place. Regardless, I am satisfied with this example and it supports what I am trying to say. Yes, the suddenness of the event is not resolvable, but the magnitude is mostly preserved, you focused on single jumps and not overall departures from a baseline. I would like to remind you that the 100ppm CO2 rises (smoothed over multi-century samples) in the glacial record took 5-10K years, I'm not sure what you are suggesting might have really happened, certainly not that our 100ppm in 1.5 century jump is not unusual.

    As another general comment about your line of reasoning, the fact that the ice core record does not conslusively rule out huge and erratic jumps and dips in CO2 on decadal scales is not evidence that it was going on either. Your corollary is technically correct, but there needs to be a mechanism for quickly removing CO2 and I don't know what you have in mind.

    Back to orbital forcing, the terminations took 5-10K years, sudden is a relative term. The terminations were initiated by increased insolation in the NH causing ice to melt and the resulting feedbacks of albedo and GHG. I would speculate that the faster rate of of rise compared to fall is due to ice sheet dynamics, ice sheets breakup faster than they form. Also CO2 is slower to be removed from the atmosphere than added.

    "Which model came close to reproduce abrupt glacial terminations?"
    This google search yields some interesting looking results:
    http://scholar.google.com/scholar?q=glacial+cycles+model

    "Therefore, we are back to the original concern: does the Earth climate need different reasons every time it "changes"?"
    Well, it seems to me you have yet to present a good reason why I should accept your assumption, upon which all of your arguments rest, that the climate is not deterministic albeit complex, on the timescales that humans care about, and therefore predictable given adequate information. Your "climate is chaotic" line is your premise, never your conclusion.

    "Is the antropogenic influence really that reason this time?
    According to all those who dedicate their lives to understanding it, yes.
    http://illconsidered.blogspot.com/2006/02/there-is-no-consensus.html

    "I guess the politically-aggressive climatologists and their apologists need to work harder, learn some modern mathematics, to understand the real nature of climate."
    I guess the intelligent part of the discussion is over.

     
  • At March 19, 2006 8:09 PM, Anonymous Alexi Tekhasski said…

    "Regardless, I am satisfied with this example and it supports what I am trying to say."

    ??? Now I guess the intelligent part of the discussion is over. My example was designed to refute your argument that "The rate of warming is on the order of 10 times faster today than seen in the ice cores." I have proven to you with layman numbers that you have no data of adequate quality from past proxies, therefore your argument is false, and cannot be used. And you are satisfied?

    About "CO2 removal mechanism". This is a last straw from you. The ice records are full of stepwise jumps, just as my "numerical" example shows. I don't need any fast removal mechanism to disporive your argument. Please remember, the argument was about "unprecedented rate", not about unprecedented spike.

    Back to orbital forcing. I used the term "abrupt termination of ice ages" as it is commonly accepted in literature, so there is no need to bring up any special timing, it is irrelevant. Now, about 100ky forcing. As I understand the discuccion in
    http://en.wikipedia.org/wiki/Talk:Milankovitch_cycles
    (section "Effect of Eccentricity"), the overall effect from changes in eccentricity is less than 0.1%, yearly-averaged. Now you need a really hard time to explain how this miniscule difference can trigger any ice age termination, especially if some researchers here claim that there is no excessive sensitiviy in climate to external conditions.

    More, a recent technically-advanced re-evaluation of Milankovic forcing,
    http://ocean.mit.edu/~cwunsch/papersonline/milankovitchqsr2004.pdf
    shows that "In no case, including a tuned core, do these forcing bands explain the overall behavior of the records." How does this work improves your statement that "cycles are fairly well uderstood"?

    Further, following your google hint, a few models popped up, e.g. this one that says in abstract:

    "A box model of the ocean-atmosphere-sea ice-land ice climate system is used to study a novel mechanism for self-sustained oscillations of the climate system on a time scale of 100,000 years, without external forcing."

    You are asking, why should you accept my "assumpion" about climate as being driven by internal dynamics? Maybe simply because your current assumption of globally-stable equillibrium failed to explain any of critical events in climate history? Isn't it enough for a good reason? Maybe you need to stop wasting your life on apparently wrong side of the argument?

    I think this topic is finished.

     
  • At March 19, 2006 9:10 PM, Blogger coby said…

    There are historical precedents for large and sudden jumps in GHG concentration. They include catastrophic releases of methane clathrates, massive volcanism events, and centuries long natural coal fires. These GHG perturbations last millenia. Look into the PETM event. The estimates for GHG increases are on the same order as what we are doing plus a century or two of the same. This perturbation lasted 100Kyrs.

    Look at it here, 55Myrs bp. The ocean sediment used to reconstrict that event only resolves to around 5Kyrs.

    I took your numbers as part of our discussion of CO2 levels not temperature. You are correct that the ice cores can not rule out global temperature jumps as fast as today's, and I acknowledge without hesitation that I have simplified things, with an inevitable loss of information, in the wording you are quoting. But it is just that, a simplification, not a falsehood and I am totally comfortable leaving out of this simple argument the possibility of unexplained wild jumping for which there is no indication whatsoever.

    And I guess I need to remind you once again that the past is just that, the past. We can learn alot from it, and we must strive to understand and explain all the evidence we can dig up, but it does not change the nature of what is happening today. Today, humans are pumping large quantities of a very important GHG into the atmosphere and it is driving a climate change unprecedented in the history of civilization. You insist we can not rule it out of the history of the glacial cycles, I say so what, humans are driving today's change.

    The correct scientific phrasing of that would put all the caveats in, "as far as we know", "very likely", "within this margin of error", "90% confidence" etc etc. And I invite you to put my feet to the fire in the comments. But these articles are a layman's expression of the high level view and are for laypeople to read. If they want the details, they can follow the links (I must put more substantiation in). Bottom line, this is not a scientific paper, there will be loss of information, but the essential message is correct!

    "The rate of warming is on the order of 10 times faster today than seen in the ice cores."
    This is absolutely true. You want to point out that we can't rule out very short lived jumps and dips, I am more than happy to say you are correct. You want to say therefore what's happening today may be natural, I will point out you are wrong.

    "The ice records are full of stepwise [CO2] jumps"

    Where are the 100ppm stepwise jumps? There aren't any.

    I will seek advice and consider weakening my claim of "fairly well understood" glacial cycles.

     
  • At April 05, 2006 1:33 PM, Blogger coby said…

    Hi Alexi,

    You are correct that it is not justifiable to say that the observed behaviour of the climate during the glacial cycles is well understood. I have ammended the original article above with that in mind.

     
  • At April 27, 2006 8:25 AM, Anonymous Peter K. Anderson a.k.a. Hartlod(tm) said…

    Seems most concepts in this discussion have already been given treatment.

    'Ice cores' are of little valid use in construction of inference, with far too many assumptions being made about their 'content'.

    "Greenhouse" behavior, let alone an effect, is not evidenced by the materials involved as part of their actual properties, so cannot be expected to exist.

    The recurring glaciations of the last ~2 to 3 million years are themselves placed within an irregularly periodic oscillation that carries climate away from such recurrences for irregular periods, again in various amounts of millions of years.

    So 'interglacial periods' are infact only relevant within specific portions of the overall climate oscillation whilst the irregular periodicity of the entire process(es) makes any claim relating to 'rate' as meaningless, there is no 'correct and natural rate' that could be expected.

    The real issue we all face is that little IS known, and supposition and opinionation involving 'greenhouse' concepts is NOT uncovering any amount of 'truth' and are infact misdirecting 'other' research.

    What Humanity IS altering is weather patterning, and THAT can be so done in a few hundred years, and the process of Humanity producing these alterations is around 300 years old, perhaps back even 400 years, tied to the growth (and sprawl) of the Human population.

    It is that citations of 'chaos' theory are being made within attempts to explain the 'lack of performance' of 'greenhouse based models', as are many other of the 'claims' regarding 'complexities' in general. Perhaps it would be easier if more attention was made of what the materials present CAN do and how they can behave.

    AS such, 'dedicating a life' to 'understandings' involving 'greenhouse concepts' is NOT of any great use in understanding what is REAL about the climate we all exist within, and never will be.

    Your's, Peter K. Anderson a.k.a. Hartlod(tm)
    From the PC of Peter K Anderson
    E-Mail: Hartlod@bigpond.com

     
  • At July 08, 2006 9:07 AM, Anonymous Anonymous said…

    RE Alexi Tekhasski's March 18 post:

    Suppose it is true that there is diffusion within ice cores of the sort alluded to in the post. The example Alexi gives is over-simplified (but in a reasonable way). Diffusion operates in a similar way to the example given - it basically results in a time series being convolved with a smoothing kernel. I would think it would be pretty straightforward to estimate the kernel from first principles (and yes, I realize that it is going to vary over time). Once one has done so, it is not particularly difficult to (partially) invert this kind of smoothing. The electrical engineering literature is full of papers on doing exactly that.

    Diffusion does destroy high frequency information, and the inversion process amplifies (some) noise. However, there are plenty of techniques for working around these problems, especially if one has some basic knowledge of how the underlying system behaves (we do) and is looking for specific features (we are). To answer the question at hand, we don't need a perfect reconstruction of the original signal, but rather to identify large transients and estimate their magnitudes / slopes.

    The point of all this is that Alexi's assertion, "I have proven to you with layman numbers that you have no data of adequate quality from past proxies, therefore your argument is false, and cannot be used", is false. Signal processing techniques can detect big enough spikes even in the presence of diffusion and noise. It may well be that ice core data are too noisy for a 100 ppm spike in CO2 levels lasting for a few centuries to be detectable, but to make such an assertion, Alexi has more work to do.

     
  • At August 17, 2006 11:00 PM, Anonymous Alexi Tekhasski said…

    RE Anonymous response of July 8, 2006:

    In your own words, you realize that the convolution kernel is going to vary over time. What you failed to realize is that it is far from straightforward to estimate that kernel from first principles, since many other mechanisms are involved. One is the process of percolation through porous firn; it was acknowledged that this process can last up to 5000 years under conditions of Antarctica, hence even ice core researchers themselves have to introduce "time lag" between ice age and air bubbles age. What they apparently overlooked is the effect of data smoothening, the effect I humbly pointed out to.

    The other effect is formation of various clathrates under enormous pressure of ice sheets, and unknown dynamics of their formation over thousands of years, and gas release during bore extraction, storage, and sample preparation. As result, the model for the "smoothing kernel" will include dozens of unknowns, and would require severe parameterization with no experimental basis to establish it. In addition, the samples have very speculative and uneven time sampling, and are already decimated to an average sampling rate of 1500 years between data points.

    Given all that, I would assert that solving the inverse scattering problem of this epic proportions is impossible, and the assertion that it is "not particularly difficult" is simply ridiculous. The electrical engineering literature might be full of toy examples, but extraction of parameters even of one-dimensional transmission line from TDR experiments still requires substantial "user intervention" and heavy guessing. The point of this remark is that no one up to present date has conducted any analysis of this sort on the ice core data, therefore my assertion that currently "you have no data of adequate quality from past proxies, so the argument of "unprecedented" growth cannot be used" is perfectly valid and is true. As result, your conclusion about who has more work to do is completely misplaced. I think I have done enough job to bring this problem up; now it is your (and AGW proponents) turn to do more work, present full analysis of errors accumulated along the whole process from air occlusion to sample extraction, and prove that there are no spikes or steps in historical CO2 concentrations.

    I wish you good luck in this process.
    - Alexi

     
  • At December 16, 2006 12:24 PM, Anonymous Anonymous said…

    I've read this entire page now, very heated debate, and even changed coby's introduction on page. I man not have all the facts but what i keep understanding more and more is the political agenda behind global warming. The UN does not want the world to stop polluting, it wants the U.S. to stop polluting and to basicly cripple its economic capabilities because they are technologicly dwarfing the rest of the world, leaving it behind.

    Alexi your a very smart guy and i would like to chat to you 1 on 1 a bit.

    Coby the vast majority of your "facts" are extreamly bias and full of holes. And yet you describe Alexi as being closed minded and unaccepting of the GW caused humans. Everytime i view your links that you post to me to convince me of GW caused by humans you do the exact opposite becuase you get shut down so bad by people with more solid opinions with less holes. You are fighting for the wrong side of the arguement. Lets prepare for global warming, not cut emmission and hope it goes away like you dream it to happen.

    How is it that we find the wooly mammoth flash frozen in the glaciers?
    How is it the in the pre historic erra fossil evidence shows that we lived on a tropical planet with far higher temperature than we have now that remained fairly consistent for that erra?

     
  • At December 16, 2006 12:38 PM, Blogger coby said…

    Anonymous,

    Eloquently describing the beauty of the green sky and tossing off unsubstantiated aspersions on the motives of all those who insist it is blue does not alter the reality of the situation.

    It is oh so easy to speak in such generalities and sound as if you are well informed, but we have all seen this trick before. Pick a scientific issue and present some scientific arguement or listen to the people who know better.

    Thanks for the comment.

     
  • At December 16, 2006 12:46 PM, Anonymous Anonymous said…

    i'm moderatley informed yes, but even at that i'm smart enough to see that at least if this problem is indeed happening from humans that cutting Co2 Emmission isn't going to solve the problem, according to your science its too late.

    Your information is not being lost Coby, information is simply contradicting yours as sceince and more developed opinions are created. Wouldn't you say your opinion would have seemd alot stronger 10 years ago?

     
  • At December 16, 2006 1:01 PM, Blogger coby said…

    If you compare the 1995 IPCC report to the 2001 report you will not find things seem either better or less certain. The 2006 report will be available in a couple of months, let's see what has been retracted/revised down.

    I don't recall anything I hae written in these articles being contradicted. There surely are contentious scientific points in climate science but I tend to discuss only those that are well established and only disputed by the well meaning though uniformed or the intentionally in denial.

     
  • At December 16, 2006 2:23 PM, Anonymous Anonymous said…

    You failed in this article to some extent to prove that statement "I tend to discuss only those that are well established and only disputed by the well meaning though uniformed or the intentionally in denial"

    After reading the blogs alot of the time your position doesn't seem so hold much water afterwards. But you have definatley helped inform me on alot of things that i didnt' know about global warming so i thank you for that.

     
  • At July 11, 2008 11:06 PM, Blogger yezi said…

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