question on whether climate is chaotic or not


by Coldcall
Tags: chaotic, climate
Hepth
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#19
Dec1-09, 09:36 AM
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Quote Quote by Andre View Post
Nevertheless, predictions go nowhere when when it is based on flawed interpretations of proxies of the climate of the past.
Or when your analysis and models can change faster than the time needed to test predictions. At least the advancements from it (modeling) will benefit us one way or another.
Coldcall
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#20
Dec1-09, 09:45 AM
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Quote Quote by Andre View Post
Exactly, and that's also the big problem. Everybody does. The general picture is lacking if you can only think for your own expertise and have to rely on others like CRU personel for the rest.
I'm certainly no expert on chaos theory and non-linear system, however i am facinated by them from a layman's perspective and have read just about every book on the subject.

So for me, i have always been sceptical of the level of certainty declared in these climate models as i know that they MUST inherently be based on chaotic physcis as is just about every other natureally occuring system in the universe. I will happily eat humble pie if someone can prove to me that climate systems are not chaotic. I'll feel really stupid but i'll eat the pie :-)

However i do agree with you, and follow both WUWT and Climate Audit, who have i think been really unfairly labelled as cranks. But I'm not knoweldgable enough on the Co2 - temp link to comment other than i have noted the apparent problems with causality dynamic between the two in the historical record - as best we can make out.
Coldcall
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#21
Dec1-09, 09:56 AM
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Quote Quote by turbo-1 View Post
That's a perfect "gotcha" question because demanding a yes or no answer assumes a dichotomy in a complex situation. It is quite possible that climate is chaotic on small scales, yet more predictable on larger scales or over time, or when observations are averaged, etc, etc. That's what the models are for.
How can a chaotic system be more accurately predictable over longer time spans when those intial condition errors grow exponentially? I'm not sure you understand how small inaccuracies turn into very large disturbances the longer the clock is running.Thats just chaos theory 101.
D H
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#22
Dec1-09, 10:58 AM
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Quote Quote by Coldcall View Post
Chaotic systems are not predictable with any level of certainty at which one can rule out surprise behaviour.
That is wrong.

I suggest you read up on the n-body problem because it is unsolvable (from any practical perspective)
That is also wrong.

But let me ask you : is climate a chaotic system?
This question is irrelevant if the timescale at which chaos ensues is far beyond the scope of the timescale of human concern.
Xnn
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#23
Dec1-09, 11:47 AM
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Coldcall;

I have a Math Professor buddy that specializes in Choas theory who might be able to help explain. However, my impression is that while weather is clearly choatic, the climate is not depending on how climate is defined.

In other words, over longer time periods, choatic properties diminish.
turbo
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#24
Dec1-09, 01:47 PM
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Quote Quote by Coldcall View Post
How can a chaotic system be more accurately predictable over longer time spans when those intial condition errors grow exponentially? I'm not sure you understand how small inaccuracies turn into very large disturbances the longer the clock is running.Thats just chaos theory 101.
And that statement shows a fundamental misunderstanding of natural systems, which have feedback mechanisms, damping factors, etc.
seycyrus
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Dec1-09, 02:02 PM
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Quote Quote by turbo-1 View Post
And that statement shows a fundamental misunderstanding of natural systems, which have feedback mechanisms, damping factors, etc.
But his statement concerns an understanding of chaotic systems. I think it is apparent that chaotic systems do necessarily contain feedback mechanisms, IIRC.

He is asking whether this natural system can be classified as a chaotic system. Does it meet the strict definition regarding sensitivity to initial conditions, density of strange attractors, and mixed topology?

I like the answer that seems to be "weather is chaotic, but climate is not". Certainly food for thought.

Regarding the one guys, ambiguous sounding answer (it *might* be). Perhaps he is merely voicing his uncertainty whether the weather can be *proven* to meet the strict definition.
Sorry!
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#26
Dec1-09, 02:19 PM
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I think that's enough about chaos system in regard to the climate. I kept noticing it come up in the Politics forums but the person was told to discuss it here so I thought I would have a looksie. D H best answered the post about chaos theory that keeps popping up in these threads. Coldcall your understanding of chaos theory is completely off-base my man.

You strike me as a layman who read in such and such a philosophical physics book then this and that out of context (or maybe, most likely actually, the book/article didn't explain it properly) and you think that's what it is. (Without any more research.) I remember running into the exact same problem you have when I took a philosophy course and we got into the subject of Philosophy of Science and we started learnin all these different theories... the best thing to do is ALWAYS check up EVERYTHING.

EDIT: Well then looks like you already admitted most of this anyways:

I'm certainly no expert on chaos theory and non-linear system, however i am facinated by them from a layman's perspective and have read just about every book on the subject.
Read some more.
D H
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Dec1-09, 02:59 PM
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Quote Quote by seycyrus View Post
I like the answer that seems to be "weather is chaotic, but climate is not". Certainly food for thought.
On a very long time scale, I cannot see how climate can be anything but chaotic. The Earth's axial tilt, argument of perihelion, and orbital eccentricity are climate drivers. On a long time scale those orbital parameters are chaotic because the solar system is chaotic. The Sun was once thought to be highly stable. However, other stars of the same type, age, chemical makeup, and size as the Sun have been observed to have chaotic output; there is no reason to think our Sun is any different.

That is on a *long* time scale, of course. On a short time scale, there is no reason (yet) to think that climate is not predictable (so long as we / Mother Nature don't flip the climate to some other stable attractor any time soon.)
seycyrus
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#28
Dec1-09, 03:20 PM
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Quote Quote by D H View Post
On a very long time scale, I cannot see how climate can be anything but chaotic. The Earth's axial tilt, argument of perihelion, and orbital eccentricity are climate drivers. On a long time scale those orbital parameters are chaotic because the solar system is chaotic. The Sun was once thought to be highly stable.
I concede this point. I had not considered such exo-planetary influences as being climate drivers. This is a rather broad scope. However, see below.

Quote Quote by D H View Post
However, other stars of the same type, age, chemical makeup, and size as the Sun have been observed to have chaotic output; there is no reason to think our Sun is any different.
Is it correct that multiple interacting chaotic systems MUST combine/interact to form another chaotic system?

Quote Quote by D H View Post
...climate is not predictable (so long as we / Mother Nature don't flip the climate to some other stable attractor any time soon.)
The size of the delta required to flip to another attractor and the required time scale involved is really what is being discussed. I think the OP was trying to address this.

Are you not *sorta* in agreement with the OP? I believe the OP is expressing confusion over some scientists inability to classify the climate as a chaotic system.
D H
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Dec1-09, 04:26 PM
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Quote Quote by seycyrus View Post
IAre you not *sorta* in agreement with the OP? I believe the OP is expressing confusion over some scientists inability to classify the climate as a chaotic system.
No. I was talking about the mainstream AGW claims, e.g. post #23, the predicted warming cited in the IPCC, etc. Those claims do not assume climate is chaotic. They do assume that climate is predictable in the short-term (10-100 years is short-term in climate science). I believe the OP was coming in with a misperception of chaos theory and with a hidden agenda based on this misperception, to wit:

"If the climate is chaotic, then why are you climate scientists pretending you can model climate?" For example, this post (emphasis mine):
Quote Quote by Coldcall View Post
Okay but i dont get how that answers my question re climate and chaos, and the fact that there appears a need for agw to argue that climate is not chaotic (hence predictable), ...
The OP continues with
but then they claim that a little more Co2 (initial condition) will cause tipping point leading to run-away gw.
The claims of a "tipping point" are pure alarmism, in my opinion, and those alarmists have about the same amount of scientific credibility as those who say global warming doesn't exist (period). That "tipping point" stuff does form a nice basis for science fiction movies --- and for scaring the masses.
Astronuc
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Dec1-09, 04:49 PM
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Of course climate is chaotic given that the inputs are chaotic.

Look at solar cycles - which are mostly, but not precisely periodice (~ 11 years).

Look at volcanic eruptions - which are relatively random events - some of which have a dramatic impact on climate.

But one can have bounded chaos, which means one cannot predict the trajetory precisely, because one cannot predict the future, besides the fact that there is still much we do not know.
sylas
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#31
Dec1-09, 05:18 PM
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Quote Quote by Astronuc View Post
Of course climate is chaotic given that the inputs are chaotic.
I tend to use the word "chaotic" to mean arbitrarily small changes in input can lead to large changes in output.

The notion of "tipping" point is related but not quite the same. It refers to cases where a system can slip from one comparatively stable condition to another as you pass a certain threshhold. A system with hysteresis, for example, has tipping points.

The clearest example of tipping points so far in this thread would be the ice ages. The evidence is not completely conclusive, but it is widely considered that ice ages over the Quaternary period, which we can see in the graphs of the thread, are caused by small changes in Earth's orbit; and moving in or out of an ice age occurs as a tipping point is passed, leading to a cascade of changes in the whole climate system that together raise, or lower, temperatures more than one would expect from the orbital changes alone.

The Quaternary contrasts with more stable conditions earlier in the Cenozoic, and one major hypothesis for this relates to the particular arrangements of land masses, which contribute to the conditions that allow for the tipping point. Specifically identified features have been the almost enclosed northern Arctic ocean and the existence of a contrasting case in the South, with a free passage for ocean circulations around the Southern Antarctic oceans.

Look at solar cycles - which are mostly, but not precisely periodice (~ 11 years).

Look at volcanic eruptions - which are relatively random events - some of which have a dramatic impact on climate.

But one can have bounded chaos, which means one cannot predict the trajetory precisely, because one cannot predict the future, besides the fact that there is still much we do not know.
Yes indeed. The 11 year solar cycles are poorly understood, but they are periodic, not chaotic. They also have a comparatively small impact. There may be stronger impacts from longer term and much more mysterious cycles, in which the 11 year cycle may be totally suppressed. This is often proposed as a factor in the "little ice age". Interestingly, the 11 year cycle seems to be particularly slow getting started for the next solar maximum at present.

Volcanic eruptions do have a dramatic impact; though it tends to be in the form of random "spikes" that then die away in the years following an eruption; or the decades following an eruption if it is a big one. The very fact that there is a recovery after an eruption indicates that the climate system itself is not chaotic, even though the input may be unpredictable.

The frequency of eruptions world wide can vary; a period of time with comparatively few major eruptions is sometimes proposed as a contributing factor for the rise in temperatures in the early part of the twentieth century.

The comment about "bounded chaos" is particularly important. Weather is certainly chaotic. Climate, however, is usually defined as the range (or bound) within weather is found. The bound itself is not obviously chaotic at all. It may have tipping points -- as we see suggested in the ice ages -- but the response seems to be much too regular to be truly chaotic, in the normal sense of the word.

In my view, the evidence shows that climate is complex, and hard to predict; that it does have tipping points although it is very hard to identify them precisely; but it is not actually chaotic, as the word is usually defined.

Cheers -- sylas
Astronuc
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#32
Dec1-09, 05:46 PM
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Quote Quote by sylas View Post
I tend to use the word "chaotic" to mean arbitrarily small changes in input can lead to large changes in output.
Chaos refers to predictability, where 'stability' refers to the impact of change on output.

The notion of "tipping" point is related but not quite the same. It refers to cases where a system can slip from one comparatively stable condition to another as you pass a certain threshhold. A system with hysteresis, for example, has tipping points.
Tipping point is different, and the real issue is one of desirable or compatible outcome with respect to the process.

Nature (a physical process) is self-regulating. The real issue with respect to 'climate change' is whether or not any change is compatible with human existence.

If climate change (warming or cooling) is occurring, then one has to consider at what point does it become incompatible with our currently way of living. This matter is a different topic.

However, the question (OP) is about whether climate is chaotic or not, and I believe we have demonstrated that it is.

The 11 year solar cycles are poorly understood, but they are periodic, not chaotic. They also have a comparatively small impact. There may be stronger impacts from longer term and much more mysterious cycles, in which the 11 year cycle may be totally suppressed. This is often proposed as a factor in the "little ice age". Interestingly, the 11 year cycle seems to be particularly slow getting started for the next solar maximum at present.
The Maunder minimum would represent an aperiodic (chaotic) event. And yes - the Sun is unusually quiescent at the moment - yet another aperiodic (and unpredictable) event. Who would have predicted that 11 years ago, let alone last year, or 6 months ago. Of course, it could return to it's more usual trend in the next few days, weeks, months or years. But we just won't know until it happens.

Volcanic eruptions do have a dramatic impact; though it tends to be in the form of random "spikes" that then die away in the years following an eruption; or the decades following an eruption if it is a big one. The very fact that there is a recovery after an eruption indicates that the climate system itself is not chaotic, even though the input may be unpredictable.
Recovery on a different climate trajectory.

Another term for chaotic is 'noisy', and the 'noisiness' can be insignificant (even if not predicatible, but it's nevermind) or it can be significant.
Astronuc
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#33
Dec1-09, 09:38 PM
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Time out pending moderation. So save your thoughts.

Thread is re-opened. Please keep posts on-topic, which is about "whether climate is chaotic or not".

Claims and assertions must be supported by evidence from textbooks, scientific journals, and other peer-reviewed sources.
seycyrus
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#34
Dec2-09, 08:27 AM
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Quote Quote by Astronuc View Post
Of course climate is chaotic given that the inputs are chaotic.
I do not know if this is correct. Do chaotic inputs into a system *always* lead to chaos? Is this proven in chaos theory? This is the question I was trying to get at when I questioned D P.

I wonder about the human body as an example. I believe that certain subsystems are chaotic, but the whole is not...?

Is the current notion that the entire universe is chaotic, but simply riding along in an attractor?

Edit: I am reminded about a certain chapter intro in Hitchhikers guide to the Galaxy.
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Dec2-09, 09:06 AM
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Vanesh already sumarized perfectly what I have on my mind when I hear words "weather", "climate", "chaos". My $0.02 is: single nuclear fission event is unpredictable, mass of the sample large enough after time t can be predicted with a very high precision. So I can imagine situation in which weather is chaotic as it is, but climate is quite predictable if you know how to describe it properly. Whether that's the case I have not the slightest idea.
Andre
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#36
Dec2-09, 09:08 AM
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Quote Quote by Astronuc View Post
Please keep posts on-topic, which is about "whether climate is chaotic or not".
However, the OP states:

Quote Quote by Coldcall View Post
.....Their argument is more or less that because climate changes over longer periods they dont need to treat it like a chaotic system (with all the inherent unpredictability that comes with a chaotic system).

But then on the other hand, they claim that a moderate increase in Co2 will cause this "tipping point" to occur causing run-away global warming....
It appears that the intention was to discuss contradictions between chaotic behavior and triggering runaway conditions.


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