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.

Thursday, March 09, 2006

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Chaotic Systems are not Predictable

(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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posted by coby @ 3/09/2006 10:34:00 AM  

33 Comments:

  • At March 14, 2006 10:11 PM, Anonymous Anonymous said…

    Following your logic:

    Gas is a dynamic system of colliding molecules, and the complexity of scattering and whole dynamics of which is chaotic, and this was experimentally proven by observation of Brownian motion. Atmosphere, on the other hand, is a collection of space and time averages of mixture of gases (that's why we can and use averages like air temperature outside your kitchen window, and local barometric pressure), and therefore is not an output of a molecular dynamics. Thus, it is a category error to think that weather is chaotic, and, as a collection of averages, must be easily predictable.

    Pretty logical, eh?

    - Alexei

     

  • At March 15, 2006 6:08 PM, Anonymous Anonymous said…

    The word "chaos" has a highly particular technical meaning as a property of some, but not all, dynamical systems. It is often popularly used as a synonym for "random". The technical term for random is stochastic. Some, but not all, dynamical systems are stochastic, usually called "stochastic processes."

    Brownian motion is usually studied as a form of ranodm motion, a stochastic process. However, the usual approximation used for the macrophysics of fluids, such as the atmosphere, begins with the Naviere-Stokes equation. At high enough Reynolds number, turbulence forms and the equation becomes impossible to calculate. So weather forcasters use a variety of approximations, accurate only for a few days.

    Even simpler seeming systems show evidence of unpredictability. The solar system, on a scale of tens of millions of years, shows signs of deterministic chaos according to at least one study. However, we can certainly have high confidence of predicting the positions of the planets for thousands of years into the future.

    Whether the climate is chaotic or random or some of both, the climate prediction models are of a similar character to weather prediction models and planet position prediction models. All these models are predictive into the future, but are not predictive into the far future. The far future for weather prediction is a matter of days. The far future for planet position predictions is millions of years.
    The far future for climate prediction models is, say, one thousand years.

    The basic point is that all these prediction models make simplifying assumptions in order to produce tractable calculations. Can we trust the results? Yes, so long as we do not try to predict into the far future. It doesn't matter whether the dynamical system is chaotic or stochastic or neither. What does matter is model validation.

     

  • At March 16, 2006 10:03 PM, Anonymous Anonymous said…

    There is no fundamental differences between "chaotic" and "stochastic/random" when dealing with dynamical systems. The difference is only in the shape of invariant measure on the corresponding attractor
    (for simple definitions, see http://www.maths.unsw.edu.au/school/articles/dynart.html , internet is wonderful!). Underlying model of Brownian motion is a colliding ensemble of elastic molecules. An ensemble of few molecules is a dynamical system equivalent to a billiard with negative curvature, see
    http://www.ams.org/notices/200404/what-is.pdf
    which leads to a Gaussian-type of invariant measure if the N is big, and hence to "true randomness".
    Molecular dynamics also could be well predictable for few collision events, which gives a prediction power for about 1 nanosecond. The Navier-Stokes equations are derived from considering interaction between elementary volumes of medium containing many molecules. Therefore, my parallel is perfectly valid, and gives a good sense of how absurd the logic of the first comment is.

    Now, you mention that "forcasters use a variety of approximations, accurate only for a few days", and "...all these prediction models make simplifying assumptions in order to produce tractable calculations....It doesn't matter whether the dynamical system is chaotic or stochastic or neither".

    These statements imply that better approximations would give researchers better forecast. This could not be farther from the truth, it is a blatant fundamental misunderstanding of the nature of attractors in real dynamical systems. Complex ("strange") attractors have inherent feature of "hyperbolicity", meaning that two identical systems (weather patterns, climates, etc.) would evolve far apart in their states no matter of how hard you try to improve underlying approximations or purify simplifying assumptions. It is just their nature, and it is pretty robust with regard to purifying assumptions. Exponential divergencies are very hard to fight after certain point in time.

    More, you mention that "chaos ... as property of some, but not all, dynamical systems.", Yes, strictly formally this is true. However, one need to assign a realistic numerical measure to chaotic and non-chaotic systems. If you just look around, how many laminar systems you can find, as compared to turbulent one? I submit that it will be a tough search, and the answer is probably "negligibly small to none".

    You already have mentioned the other end of the spectrum, solar system. Please take a look farther in space:

    http://arxiv.org/PS_cache/astro-ph/pdf/0410/0410258.pdf

    The author concludes: "As we saw, chaos is an inevitable ingredient of the Universe". BTW, the article contains 47 references to relevant studies, not just one...

    In short, on every classical scale of the Universe, from molecules to galactics, the chaos is a norm of dynamics, while the smooth, solvable, and totally determinnistic motions are rather exceptions. For this reason, there is absolutely no scientific reason to assume that the large dynamical system of coupled atmosphere, ocean, and plate tektonics is an exception. As the report concludes, chaos just needs particular efforts to deal with. Maintaining that the Earth is flat is not constructive.

    The basic point is that it is of fundamental importance to identify the hyperbolic attractor that governs climate behavior, in order to explain historical data. The "equillibrium" attractor (which currently is in favor among certain dominant group of researchers) is a ridiculous oversimplification of the problem. The other assertion of fundamental importance is that the equillibrium on Earth is not static as currently assumed in all "force-feedback" speculations, but the "eqiullibrium" is dynamic, which means that what needs to be compared are RATES OF CHANGES in concentrations and temperatures, or the "balance" equations must be differential at least, not just "CO2in = CO2out + fossil_emissions".

     

  • At March 31, 2006 10:21 AM, Anonymous Anonymous said…

    I am not sure what do you mean under "change of perspective" and what makes the chaos theory possible or not, the perspective is apparently more complex than the relationship you just described. Strange attractors in complex spatially-distributed systems are complex, their "shape" evolves on a hierarchy of time and space scales.

    Let me give an example: it is commonly accepted that the turbulence is a manifestation of a motion on a strange attarctor. By averaging this motion over a reasonable time, say, seconds, one can obtain a sort of "system characterization", turbulent viscosity. However, this averaging does not prevent our atmosphere from having Rossby waves and hurricanes. No matter how do you try to better estimate the turbulent viscosity, hurricanes and planetary waves will be there. Similarily, averaging the strange attractor of weather over 30 years does not remove its large-scale dynamics. To be sure that this large scale dynamics exists, it is sufficient to look at historical glaciation/deglaciation data.

     

  • At April 05, 2006 3:08 AM, Anonymous Anonymous said…

    One of the important characteristics of chaotic systems is that they are chaotic at all scales. Climate is simply a whole lot of weather; weather is chaotic, so how is climate not? Quantifying a chaotic (non-linear) system does not make it determiinistic, regardless of how spiffy your simulation or how many computers you throw at the problem...

     

  • At April 05, 2006 10:46 AM, Blogger coby said…

    "One of the important characteristics of chaotic systems is that they are chaotic at all scales."

    If this is true, then clearly climate is absolutely not chaotic. The existence of perfectly regular diurnal and seasonal cycles disqualifies climate as chaotic by your definition.

    Further, your claim that any system that encompasses subsystems that are chaotic must itself be chaotic does not strike me as reasonable. If I close all the doors and windows in my house and leave the ventilation system running at one setting we will end up with a consistent pattern of air movement. This is built on top of the chaotic behaviour (brownian motion) of the air molecules but is not itself chaotic.

     

  • At April 05, 2006 3:48 PM, Anonymous Anonymous said…

    Whether or not you think it reasonable, it is in fact, the case. Regular (appearing) cycles do not mean what you seem to think, either. The "regular" ice age cycle appeared after a transition from a time when there was no such cycle; the system changed to a new attractor - that's what chaotic systems do. There is a subtlety to natural, non-linear systems that makes them anything but deterministic.

     

  • At April 05, 2006 10:15 PM, Anonymous Anonymous said…

    Coby, your example is simplified to the level of absurd, and also is not fully defined. When you say "leave the ventilation system running at one setting", do you mean "air conditioner", or only ventillation? What about the outside temperature?

    In any case, your example is not worth to examine just to find that there will be substantial temperature fluctuations in any case, and their frequency spectrum will be continuous down to zero.

    To better understand what kind of real science is involved in much simpler cases (that include hydrodynamics of a fluid with two diffusive additions, say, temperature and salinity), I would refer you to the following article:

    [Knobloch, Moehlis 1999]

    If you want some sensation, look at the Figure 4: don't the bursts just look like glaciation-deglaciation periods? But more seriously, look what does it take to analyze even earliest instabilities and bifurcations even in highly-purified models. Although the article never mentions "ocean" or "atmoshpere", I can tell you that experimental studies (upon the whole theory was inspired) were conducted under proposals related to physics of Earth.

    Cheers,
    -aap

     

  • At April 06, 2006 5:08 PM, Anonymous Anonymous said…

    On a second thought, I'd like to take it a bit back with regard to your ventillation example. But first about "perfectly regular diurnal and seasonal cycles". Obviously you are very wrong with this statement: the diurnal and seasonal cycles are far from perfect, yesterday it was cloudy, today it is sunny and hot, a very big difference. Winters happen to be mild or harsh, same for summers.

    Regarding your example, let's first fully define external conditions for it. Since you are in Canada, let's assume that it is cold outside, and even is you close all windows and doors, your walls will be conducting heat, so the ventillations alone will not work for your comfort. Therefore there must be a heater in your house, and let's assume that the heater is quite powerful. So what do you do? You turn your ventillation on, and the heater control on. The ventillator will stirr eddies of cold air that are falling down along the colder walls and windows, your computer also generates some warm exhaust, so there will be some turbulent mixing in air resulting in fluctuations of temperature near the surface of where you sit, SST, Seat Surface Temperature. But the global house temperature will be gradually dropping until the sensor in your heat controller flips and turns the heat ON. Then a strong wind of hot air will blow for a few minutes warming your house (we agree that your heater is powerful) until the sensor reaches upper threshold of control setting, and shuts the heater OFF. Then the ventillator will continue to blow, room temperature slides gradually down and down, and the cycle repeats. Now, I bet you will have substantial difficulties if you want to predict precisely when the heater will turn ON and OFF, although all long historical records show some visual periodicity. So, I think that this analogy should be good. What you only need is to figure out what flips the IR shutter on our Earth :-)

     

  • At April 06, 2006 5:30 PM, Anonymous Anonymous said…

    I think an important aspect of calling climate chaotic (rightly or wrongly), is that when you get a trend, you can't expect a straight line. Thus at some times you get accelerated warming much greater than the actual trend. Positive feedbacks can have a major effect for a time and then just peter out. While you wait, things look far worse than they are.

    I expect that such an effect is short term and unpredictable.
    How could it be otherwise?

    Another point is "Climate forcings in Goddard Institute for Space Studies SI2000 simulations" by

    Hanson et al 2002 refers to unforced variability as "chaotic" :

    "A fundamental challenge regarding climate is to
    determine how much of observed climate change is a
    response to climate forcings, as opposed to chaotic
    (unforced) variability. A climate forcing is an imposed
    perturbation of the Earth’s energy balance with space.
    Forcings arise naturally, as with aerosols injected by volcanic
    eruptions, and from human activities, as with increasing
    greenhouse gases."

    It's the start of the introduction on page one:

    http://pubs.giss.nasa.gov/docs/2002/2002_HansenSatoN.pdf


    Doug L

     

  • At April 07, 2006 5:31 PM, Blogger coby said…

    Doug,

    It is not my position that there no chaotic aspects to climate, even if you are restricting your self to discussions of global mean temperature. I only object to people cliaming it is chaotic on all time scales. Object is not the right word, perplexed might describe it better.

    I thought Alexi and I had come to an agreemet earlier somewhere that climate exhibits chaotic behaviours on many different scales, but it is broadly deterministic in response to external forcings on the time scales that humans care about, ie up to several thousand years.

    That strikes me as a very reasonable description.

     

  • At April 07, 2006 7:57 PM, Blogger coby said…

    Alexi,

    Much as I love analogies, I won't pursue this one. I had a singular purpose and just wanted a thought experiment to refute the principle behind "Climate is simply a whole lot of weather; weather is chaotic, so how is climate not?" That principle seems to be: if A is chaotic and B is made up of lots of A's then B must be chaotic.

    So I want a simple system to refute this on principle. How about this: billiard balls are made of molecules, all of which are moving in a chaotic manner. This principle implies that the motion of billiard balls on a billiard table is chaotic. While you may have some interesting argument that makes such a claim it will be irrelevant for the purpose of any player of billiards.

     

  • At April 10, 2006 6:02 AM, Anonymous Anonymous said…

    Heh. Nice try. A billiard ball is hardly an example of a dynamic system: lacking the impetus of the cue, it'll just sit there.

    Not so, weather and climate.

    Weather displays cyclic variation, as does climate; no numerical model in existence can accurately predict the weather five days in advance. he range of the local climate can help to rule out things like snow at the equator - there's an underlying pattern tp weather as well as climate. But perturbations to the system, such as storms (in the case of weather), or everyone's favorite, "forcing due to greenhouse gases" (in the case of climate) produce a chaotic result; they do not lend themselves to accurate prediction. 'Tis the way that it is.

     

  • At April 10, 2006 6:51 AM, Blogger coby said…

    What is your evidence that the climate responds to external forcings in a chaotic manner? "Tis the way is it" not counting as such.

     

  • At April 10, 2006 9:00 AM, Anonymous Anonymous said…

    It's a non-linear system; the vast majority of differential equations that play a role in natural systems are non-linear (turns out that the Shockley Diode Equation that led to the transistors that led to the microelectronics that make your little blog possible is a rare linear, first-order differential equation). "Chaotic" is how one describes the behavior of a non-linear system.

     

  • At April 10, 2006 9:29 AM, Blogger coby said…

    I suggest you revisit the definitions of chaotic and non linear systems, and then come back to "my little blog" with an answer to my request for evidence that the climate responds to external forcings in a chaotic manner.

    Thanks.

     

  • At April 10, 2006 3:20 PM, Anonymous Anonymous said…

    "In nonlinear systems one encounters such phenomena as chaos effects, strange attractors, and freak waves." From the Wikipedia "Nonlinearity" link you provided. Okey-dokey.

     

  • At April 10, 2006 3:53 PM, Blogger coby said…

    "chaos theory describes the behavior of certain nonlinear dynamical systems that under certain conditions exhibit a phenomenon known as chaos."
    from the chaos wiki link. It looks to me like non-linear does not equal chaotic. Some are, but they are not all by definition. Your quote does not say that all non-linear systems exhibit all of these behaviours.

    So what is you evidence that the climate system is chaotic?

     

  • At April 11, 2006 1:27 PM, Anonymous Anonymous said…

    Coby, it is sufficuent to look at the ice core data. One has to really stretch his imagination to declare this kind of signal as "global equilibrium" and try to calibrate his models on accidentally-flat segments of data.

    Speaking about your billiard example, it is a great analogy! First, it really separates internal molecular dynamics of a system component (a ball) from the whole global system (billiard). In my hydrodynamical example, one may have a false impression that better averages over macroscopic volumes of gas or fluid could improve on predictability of turbulence. The case of a billiard ball is perfect in this sense.

    Second, ironically, billiards ARE chaotic systems even if the ball is ideal, and regardless to your simplified principle; Google for "Sinai billiard" or "Bunimovich staduim". There is one very relevant corollary from this fact "for the purpose of any player of billiards": they shouldn't expect to win the game with one shot. You can predict the motion for one-two or three collisions, but then all bets are off. Similarly, if the climate is on the move, it will likely to go on until it hits some natural wall (we know from geological history that the Earth climate does have "walls").

    Another misconception of yours is about how climate responds to external forcings. No one insists that it responds in a chaotic manner locally (in time and state), an attractor is called "an attractor" because local perturbations eventually decay, the motion gets attracted back to the attractor, and continues along it, simple or strange one. Climate response to perturbations is in little way indicative of the global nature of it's dynamics.

     

  • At April 11, 2006 4:36 PM, Blogger coby said…

    Hi Alexi, you may have heard this one:

    A mathematician and a physicist agree to a psychological experiment. The (hungry) mathematician is put in a chair in a large empty room and his favorite meal, perfectly prepared, is placed at the other end of the room. The psychologist explains, "You are to remain in your chair. Every minute, I will move your chair to a position halfway between its current location and the meal." The mathematician looks at the psychologist in disgust. "What? I'm not going to go through this. You know I'll never reach the food!" And he gets up and storms out. The psychologist ushers the physicist in. He explains the situation, and the physicist's eyes light up and he starts drooling. The psychologist is a bit confused. "Don't you realize that you'll never reach the food?" The physicist smiles and replies: "Of course! But I'll get close enough for all practical purposes!"

    In short, I don't think we really disagree alot on the technicalities of climate prediction, I think we just differ in whether or not it is worth trying.

     

  • At June 01, 2006 9:43 PM, Anonymous Anonymous said…

    Coby,

    Are you sure that the psychologist correctly estimated the direction to move the chair? If, as you said, the room is large, the chair may end up way off the meal location.

    (this seems to be a very good example how local "sensitivity" measurement may end up completely useless for real practical purpose)

    :-) :-)

    - Alexi

     

  • At February 20, 2007 5:01 PM, Anonymous Anonymous said…

    Now Coby is saying that Meteorology follows nice perfect smooth sine-waves.

    -TEMPERATURE!

    -PRECIPITATION!

    -CLOUDY OR CLEAR!

    All perfect little sine-waves acording to the neo-Communist Coby.

     

  • At March 14, 2007 11:02 AM, Anonymous Anonymous said…

    I was bemused to discover, when following a link to "How to talk to a climate sceptic" to discover that a comment I have made on RealClimate had triggered a thread here.

    It inspired some sensible comments and more than a little huffing and puffing that missed the point.

    The point is that "chaos" has a precise mathematical definition. It is a property of some, but not all, non-linear dynamical systems.

    Weather is a dynamical system consisting of physical, chemical, and biological properties of a approximate sperical shell -- the atmosphere and the oceans -- with some boundary effects from the land surface and outer space. It is almost certainly chaotic.

    Climate is a collection -- varying according to the tastes of the compilers -- of spatial and/or time averages of the weather system. It is not a dynamical system (if you don't agree, I would be happy to contemplate pointers to a description of a dynamical system for which climate is the output). Saying that climate is chaotic is a category error that applies a property of one category -- dynamical system -- to something that doesn't belong to that category -- climate.

    Alexi's gas-atmosphere-weather example actually makes my point, although he indulges in a bit of bait-and-switch. The accomplishment of statistical mechanics was to show that appropriate statistical averaging of the output of a chaotic molecular-billiard-ball can be used as a derivation of Carnot's empirically-discovered (-invented?) laws of the thermodynamics of macro-scale gas systems. Carnot's laws are not chaotic. Weather is itself a dynamical systems whose components include the atmosphere. Weather is almost certainly chaotic. Climate is a collection of spatial-temporal averages of weather. It is not the output of any dynamical systems and, thus, cannot be said to be chaotic.

    Perhaps Alexi is using the PoMo LitCrit or the Greek Mythology definitions of "chaos", in which case, I suppose he can say anything about it he wants.

    Contrary to Alexi's assertion, there is a 'fundamental difference between "chaotic" and "stochastic/random" when dealing with dynamical systems', although the presence of noise in all physically measured systems can make it difficult to distinguish between them. The following quote from the Non-Linear FAQ explains the distinction:

    "Define the error as the difference between the time evolution of the 'test' state and the time evolution of the nearby state. A deterministic system will have an error that either remains small (stable, regular solution) or increase exponentially with time (chaotic solution). A stochastic system will have a randomly distributed error."

    Alexi is correct that more precise approximations do not make chaos "go away", but that fact is not relevant to the question of whether it is correct to describe climate as chaotic.

    Best regards.

    Jim Dukelow

     

  • At March 14, 2007 3:22 PM, Anonymous Anonymous said…

    Alexi writes:

    "In short, on every classical scale of the Universe, from molecules to galactics, the chaos is a norm of dynamics, while the smooth, solvable, and totally determinnistic motions are rather exceptions. For this reason, there is absolutely no scientific reason to assume that the large dynamical system of coupled atmosphere, ocean, and plate tektonics is an exception."

    I agree with the second sentence, but not the first, although I don't think GCMs incorporate plate tectonics, other than putting the appropriate pulses of ash and sulfuric acid into the atmosphere when attempting to reproduce known climate history.

    The first sentence peculiarly asserts that chaos is the norm of dynamics at all scales in the universe. This presupposes a quantitative measure of some sort on the collection of dynamical systems at all scales, which I am reasonably sure does not exist. Second, systems with purely deterministic dynamics are pretty common. Looking just at fluid flow, chaos/turbulence shows up at a Reynolds number of 2000, gove or take a factor of two. An increase in fluid velocity and/or a decrease in fluid viscosity and/or an increase in the characteristic distance of the flow will tend to increase the Reynolds number. The corollary is that high viscosity flows, low velocity flows, and flows at small scales will all tend to be laminar -- that is, purely stably deterministic and not chaotic. You can see laminar flows in your kitchen as you pour the honey or run the faucet at very low flows. The flow of blood in your body is mostly laminar, enough so that "carotid bruie", the noise of turbulence in the carotid artery in the neck, is an important diagnostic sign for partial blockage of the carotid artery, which threatens the blood supply to the brain. Ocean currents, other that the highest velocity currents, will be laminar, because of low velocities. Flows in the earth's mantle will be laminar because of low velocity and high viscosity. Etc., etc., and so forth.

    Best regards.

    Jim Dukelow

     

  • At April 30, 2007 10:03 PM, Anonymous Anonymous said…

    Jim, you are confusing several different concepts. First, dynamic systems are completely deterministic, by definition. A dynamic system can have an attractor that has chaotic properties. It is still a fully-deterministic system, in the usual sense that the time trajectory of its state is fully determined by its initial state, forever. The attractor can be very complex and can exhibit ergodic properties with a certain invariant measure. In this case the behavior may look random on certain time scale. A system is "stochastic" when the randomness of its subsystem is postulated or introduced via some iterative mathematical constructions, usually when the actual nature is hard to calculate from first principles, or the nature is well known, like a Gaussian noise. It you look at what I wrote, you may find out that I tried to avoid the term "stochastic system" where possible. So, your "Non-linear FAQ" (without reference) is simply, unconditionally wrong.

    Now, any finite smooth function on a chaotic attractor is still a chaotic function, especially if the function does not convolve state trajectories for longer than some characteristic time scale of the solutions. 30-year average of a weather attractor (coupled with ocean dynamic and carbon pumps) is a simple smooth function with a kernel that is much shorter than experimentally observed glaciation/deglaciation cycles. Therefore, it is chaotic, which can be supported by instrumental observations of continuity of its power spectrum.

    Lastly, even flows in the earth's mantle are pretty much turbulent, although it is a special form of convective turbulence. To enjoy some science of mantle convection, you can visit this site:
    http://www.gps.caltech.edu/~gurnis/Movies/movies-more.html

    Yes, there are laminar flows. However, I challenge you to take your own example of the facet flow in your kitchen. Considering that your facet is about 30cm above the sink surface, please go ahead and try to determine the turning range of the facet knob that would generate a laminar flow in the jet. I bet the range will be _ZERO_. Try it.

    Regards,
    -Al Tekhasski

     

  • At July 18, 2007 12:03 PM, Anonymous Anonymous said…

    http://grida.no/climate/ipcc_tar/wg1/504.htm

    The climate system is particularly challenging since it is known that components in the system are inherently chaotic; there are feedbacks that could potentially switch sign, and there are central processes that affect the system in a complicated, non-linear manner. These complex, chaotic, non-linear dynamics are an inherent aspect of the climate system.

     

  • At July 18, 2007 12:04 PM, Anonymous Anonymous said…

    suck on that lib. let's see you weasel your way out of this one!

    Global warming = liberal propaganda

     

  • At July 18, 2007 1:19 PM, Blogger coby said…

    Charming.

    As your own quote states, there are components of the climate system that are chaotic, this does not mean that the systm as a whole is chaotic nor that all aspects of it (such as global average temerature) are chaotic.

    Hope that isn't too "liberal" for you.

     

  • At July 18, 2007 2:20 PM, Anonymous Anonymous said…

    Good job lib. Cherry picking as usual.

    "In particular, these arise from the non-linear, chaotic nature of the climate system …"

    Why don't you just admit that you believe in this nonsense cause you have a liberal bias and the whole point behind these bogus apocalyptic predictions made by these fake models is so you libs can force more socialism on america. That hansen fella had alot of forsight. He anticipated the collapse of his ideal society (the soviet union), so in 1988, he went before congress and made bogus predictions as to how the climate was going to change. too bad alot of people believed him, cause a decade later, patrick michaels showed that hansens predictions fell short of what actually happened. yeah, ok, these climate models are accurate; and communism works. good job coby.

     

  • At July 18, 2007 2:39 PM, Blogger coby said…

    Um, speaking of cherry picking, you do realize you are quoting from the IPCC report, a report that clearly reflects a scientific position that the climate system is predictable in ways useful for policy decisions. Climat science does not seem to agre with your opinion, and unfortunately in matters of science not all opinions are equal.

    Very funny stuff about Hansen and communism btw, but you need to update your paranoias, islamic terrorists are the Enemy now.

    Patrick Michaels' testimony about Hansen's predictions was perjury.
    (check here)

     

  • At July 18, 2007 2:54 PM, Anonymous Anonymous said…

    funny how you link back to your own blog. Yeah, no bias there.

    You and your fellow liberal zombies take the IPCC reports for gospel! If they say it, it must be true. Why not be consistent and accept that EVEN they say that the climate is chaotic. That probably explains why hansen's predictions were false because the climate IS chaotic and there's error in the initial conditions and such errors propagate exponentially! You can't even tell me what temperature it will be 5 days from now, and so you and hansen have the nerve to tell us that we need to change our lifestyles (and wreck the economy in the process) to avoid some "catastrophe" that's predicted by some fake climate model. You sound like Al Snore. I better check what you quote from these "scientific" reports. You might just tell me the oceans will rise 22 meters when the report itself only says it will rise 23 inches!

    I eagerly await your incoherent angry-liberal response.

     

  • At July 18, 2007 3:10 PM, Blogger coby said…

    I link to my own blog because I have addressed these same tired old arguments before, why should I redo it with some random individual who doesn't even have enough guts to use a ficticious screen name let alone his own? All of my articles are well sourced, I ask no one to just take my word for any of it.

    Climate prediction is a boundary conditions problem, not an initial conditions problem. When these model experiments are run the begin by running the model with static forcings until an equilibrium is acheived. Inital conditions ar not important, as opposed to weather prediction.


    Hansen's predictions were spot on.
    http://illconsidered.blogspot.com/2006/04/hansen-has-been-wrong-before.html

    Can you please provide some justification for your chicken-little alarmism that reducing CO2 emissions will wreck the economy?

    I eagerly await your incoherent angry-liberal response.

    LOL! Thanks for that, I can always use a good laugh! You really need to develope a sense of irony...

    (was that angry and hateful enough for you?)

     

  • At July 18, 2007 3:18 PM, Blogger coby said…

    Sorry, osta link:
    http://illconsidered.blogspot.com/2006/03/we-cant-even-predict-weather-next-week.html

     

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