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Climate and chaos

Posted on 7 September 2010 by chuckbot

One of the defining traits of a chaotic system is 'sensitive dependence to initial conditions'. This means that even very small changes in the state of the system can quickly and radically change the way that the system develops over time. Edward Lorenz's landmark 1963 paper demonstrated this behavior in a simulation of fluid turbulence, and ended hopes for long-term weather forecasting.

However, climate is not weather, and modeling is not forecasting.

Although it is generally not possible to predict a specific future state of a chaotic system (there is no telling what temperature it will be in Oregon on December 21 2012), it is still possible to make statistical claims about the behavior of the system as a whole (it is very likely that Oregon's December 2012 temperatures will be colder than its July 2012 temperatures). There are chaotic components to the climate system, such as El Nino and fluid turbulence, but they all have much less long-term influence than the greenhouse effect.  It's a little like an airplane flying through stormy weather: It may be buffeted around from moment to moment, but it can still move from one airport to another.

Nor do climate models generally produce weather forecasts. Models often run a simulation multiple times with different starting conditions, and the ensemble of results are examined for common properties (one example: Easterling 2009). This is, incidentally, a technique used by mathematicians to study the Lorenz functions.

The chaotic nature of turbulence is no real obstacle to climate modeling, and it does not negate the existence or attribution of climate change.

 This post is the Basic version (written by chuckbot) of the skeptic argument "Climate is chaotic and cannot be predicted".

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Comments 1 to 27:

  1. Roulette is a chaotic system. Nevertheless, you can easily predict the odds of winning. If they change much from their predicted values banks will notice. Chotic does not means that average behaviour is unpredictable. Only the short terms trajectory is. This is why this si called deteerministe chaos. Nevertheless, you might observed unpredictable jump in dynamics. Pickover called them "magic doors". This is a well documented phenomenon.
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  2. But everybody is fast on the draw to attribute the heat wave of 2010 or the monsoon disaster in Pakistan to climate.
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  3. Not so, TOP. Although it is projected/predicted that global warming will result in higher global temperatures (and therefore hotter heatwaves) and more/heavier precipitation in certain regions, I can't see where "everyone" is attributing particular heat-waves or monsoon disasters to climate, let along global warming. They do, however, add to the long list of evidence backing the theory of global warming, and are more significant than the claims of the so-called skeptics whenever we have a local cold spell or lots of snow.
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  4. Top: "But everybody is fast on the draw to attribute the heat wave of 2010 or the monsoon disaster in Pakistan to climate." No they're not. Some people have started asking what statistical methods might allow us to attribute probabilities that these sort of events are climate-change driven.
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  5. Dan, that's an interesting comment about determining probabilities for extreme weather events. For instance, the Russian heat wave and wildfires... this is a weather event which has never happened before in recorded history. As I see it that means either it wasn't possible under previous climate conditions or it would have required such a rare combination of factors that it just never happened until now. If it were possible to put numbers to that it'd go a long way towards putting the whole 'no single weather event can be directly attributed to global warming' bit into proper perspective.
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  6. TOP - "everybody"??? The science position is that warming results in more energy and more water in the atmosphere so extreme events will become more common. This is a statement about trends not events. I suggest you get your science from scientists.
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  7. Dan Olner (#4), Tamino has tried this: http://tamino.wordpress.com/2010/08/12/red-hot/
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  8. "This is, incidentally, a technique used by mathematicians to study the Lorenz functions." Mathematicians were the ones who invented collatorised debt obligations, which is a fancy way of saying 'passing the buck whilst at the same time generating fees'. "Models often run a simulation multiple times with different starting conditions, and the ensemble of results are examined for common properties". Strange that they you don't mention the key issue, that the value of the components of the simulations (not starting points) aren't varied because that would produce an outcome not suited to the researcher. You only mention the starting conditions can be changed/variable. So you are willing to assume initial conditions can vary, but none of the model factors/conditions/inputs vary over time, or could be wrong, or the values themselves could themselves be subject to initial conditions. Very telling.
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  9. thingadonta, your comment probably will be deleted because of its assertion of researchers intentionally biasing their results in the direction they want. You could just as well have written your comment without that attribution of ill intent. But to your complaint that items other than the starting points are not varied: Please notice that this particular post is about chaos. The key aspect of chaos is that minor changes in the starting conditions cause big changes in the local/near-term trajectory of the system. That is why changes in starting conditions are mentioned in this post. Other aspects of climate models are not relevant to this particular topic of chaos. Please stay on topic.
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  10. "I suggest you get your science from scientists. " scaddenp most people don't get their science from scientists but filtered through the news. If a scientist or science institute put out a press release suggesting the Moscow and Pakistan events are tasters of whats to come from climate change it's impossible not to think that the two things are not going to become linked. In this article NOAA have been very clear in their explanation that the recent winter snows in the US are related to two weather events coming together in a rare conjugation and equally clear that these events have nothing to do with climate change. NASA GISS discuss Moscows summer events under the headline "What Global Warming Looks Like". It's actually possible to be equally clear about the Pakistan and Moscow events being linked to very specific weather conditions. These were driven by changes in the jet stream. Leading to heavy monsoon rains falling in the mountainous catchments of Pakistans rivers rather than lower down on the plains. This paved the way for the terrible flood surges. The jet stream shift also allowed hotter weather to move north over Moscow. It's very easy to be as clear that these events are unrelated to climate change but NASA GISS choose not to do this. I see why NOAA are so clear about the cold winter, some were using it to suggest the end of global warming. Without resorting to bias and underhand tactics I can't explain why NASA GISS can't be equally clear about this summers events. This scaddenp is propapanda dressed up as science.
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  11. Or what about these quotes from Kevin Trenberth in a Reuters article. This is science from the scientists via the media. Don't forget the fear mongering 'War on Terror' quote from the senior scientist at the end of the piece. All good science!
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  12. Sorry, where in the NASA GISS piece does it say that the extreme events were caused by global warming? Record temperatures and extreme event are CONSISTENT with global warming but its drawing a long bow to suggest that this is propaganda not facts. I don't think the NOAA article is clear that events have nothing to do with climate change. Its pointing out that cold spells aren't inconsistent with climate change. However, I don't think we actually know a warming planet will affect the patterns responsible for those weather events yet. Papers to contrary welcome. It seems hardly surprising to me that you get more precipitation in places in a warmer world, and that if temperatures drop below zero, then it will fall as snow.
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  13. Science says extreme event will become more common, Trenberth notes that dealing with an extreme event may make the Russians realise that all in not a bed of roses with global warming. What he is not saying is that heat wave was caused by global warming. Only - get used to them because they are going to become more common.
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  14. Wow, HR @10, that's an amazingly biased reading of two very conservative, patient articles explaining weather and climate variability. I'd be thrilled if the people in the news media read and understood those two articles, because if they did, climate reporting would be much more level-headed, even, and accurate. If anyone is interested, NOAA has a nice interactive graphic on how arctic ice retreat can affect winter weather in eastern North America and eastern Asia. It should definitely be linked to in some of this site's responses -- like the "gee, it's cold in X today, where's the global warming?" response.
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  15. re 9 Tom Dayton I'll try and keep out assertions of ill intent. However, researcher bias is well-known, its not necessarily deliberate or conscious, its largely unconscious/assmumptive, and it includes experiments/models being affected by the researchers themselves not only in selection and design, but also as the experiment/model proceeds. "The key aspect of chaos is that minor changes in the starting conditions cause big changes in the local/near-term trajectory of the system" I always thought chaos was deined as a system in continual instability/flux, not just at the starting point, but ongoing, at the 'edge of chaos' so to speak. Such is also the argment for tipping points as a system proceeds. I fail to see why it should only apply at initial conditions. I had just writte the above when I checked and found that wiki actually states that mathematicians only define chaos are dependant on initial conditions (http://en.wikipedia.org/wiki/Chaos). Ah, those mathematicians are at it again-re-defining concepts based on the own field's assumptions; but wiki does mention, in passing, that this definition is done "ignoring the effects of the uncertainty principle"-which most scientists know is pervasive, ongoing over a the course of time or model or experiment, and can't actually be 'ignored' to suit assumptions in a model.
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  16. No, thingadonta, mathematicians did not redefine the concept of chaos based on their own field's "assumptions." Researchers discovered a phenomenon that exists in nature, and reused a common English word as its label, but in doing so they clearly specified its precise meaning in that technical usage. The opposite frequently happens as well--clearly defined scientific terms often become lay terms with much less clearly defined meanings.
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  17. thingadonta - can I suggest you move this "models arent reliable". The source code for models are public domain; a massive literature covers them. What you state is valueless FUD without some evidence to back your assertion of bias unconscious or otherwise in the models. Actually I do think there is one bias in the models - that they accurately reflect known physics.
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  18. HR #10, can you say definitively that the jet stream shift and other weather conditions (e.g. generally higher local temperatures / increased water vapor content in the atmosphere) which led to the Russian heat wave and Pakistan monsoons were even possible under the climate of a hundred years ago? If not (and the answer is definitely "not") then you REALLY need to ponder the old adage about glass houses and stones before you go start making definitive statements and accusations of scientific bias. Because even setting aside that they DIDN'T say those things were "caused" by global warming... you saying they weren't is every bit as unfounded as it would have been if they had said they were.
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  19. #18, the jet stream shift that caused the heat wave (Meridional flow) was of course "possible" 100 years ago and there were outlier years. But you are generally correct that the Meridional flow is more likely now than it was 100 years ago. See Figure 3.10 here www.salemstate.edu/~bhubeny/Hubeny_Dissertation.pdf for example. This particular paper does not discuss what causes the jet stream shifts. But please don't put words in HR's mouth: he did not say "caused", only "related". Also he did not mention "increased water vapor content" although it would be interesting to see how that might be linked to a jet stream shift. It seems to me that jet stream shifts have a lot more effect on water vapor than water vapor has on jet stream shifts.
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  20. HumanityRules writes: NASA GISS discuss Moscows summer events under the headline "What Global Warming Looks Like". This seems like an entirely reasonable headline to me. Global warming does not mean that every place will be a tiny bit warmer each year than it was the previous year. Spatial and temporal variability continues, but there are proportionately more extreme warm events and fewer extreme cold events. Eventually, conditions that were previously extreme on the warm side become normal, while conditions that were normal on the cold side become rare. Thus, the GISS headline is literally correct: the summer of 2010 is an indication of where we are headed. It is a good example of What Global Warming Looks Like -- a planet that still has spatial heterogeneity in climate, but where in a given month the few cooler-than-normal places are outweighed by a lot of somewhat-warmer-than-normal places and a couple of extraordinarily-hotter-than-normal places. That IS what global warming looks like, HR, and GISS is entirely correct to say so. In contrast, the occasional spatial or temporal cold anomalies (like parts of the US last winter) are best described as reminders of the climate we're leaving behind. They're not representative of what most places will feel like most of the time in 2020 or 2040 or 2060. So the asymmetry you object to in how people respond to warm vs cold anomalies is actually entirely reasonable. HumanityRules continues: It's actually possible to be equally clear about the Pakistan and Moscow events being linked to very specific weather conditions. [...] It's very easy to be as clear that these events are unrelated to climate change Like CB Dunkerson, I observe that you write this with a great deal of certainty, which IMHO is entirely unjustified. How do you know that these events are unrelated to climate change? That's a remarkable statement, one that's far more extreme than anything one generally sees from the "mainstream science" position on this website (and far more radical than anything in the GISS article you dismiss as "propaganda"). I'm sure you're familiar with the "loaded dice" analogy. AGW doesn't deterministically and singlehandedly cause particular heat waves, droughts, or floods. But it loads the dice in favor of more heat, and in favor of greater heterogeneity in the hydrologic cycle. When you roll a six on a loaded die, you can't say that the loading caused the six, but you can certainly say that it affected the probability (and that an abnormal string of sixes is "what the dice will look like" if we keep loading them). In contrast, HR, your definitive statement "It's very easy to be as clear that these events are unrelated to climate change" is rather shocking. HR concludes: Without resorting to bias and underhand tactics I can't explain why NASA GISS can't be equally clear about this summers events. This scaddenp is propapanda dressed up as science. I strongly disagree. The GISS article seems entirely appropriate in its discussion. Let's quote the relevant section:
    Climate anomalies in the Northern Hemisphere summer of 2010, including the heat in Eastern Europe and unusually heavy rainfall and floods in several regions, have received much attention. Are these climate anomalies an example of what we can expect global warming to look like? [...] The location of extreme events in any particular month depends on specific weather patterns, which are unpredictable except on short time scales. The weather patterns next summer will be different than this year. It could be a cooler than average summer in Moscow in 2011. But note in Figure 1, and similar maps for other months, that the area warmer than climatology already (with global warming of 0.55°C relative to 1951-1980) is noticeably larger than the area cooler than climatology. Also the magnitude of warm anomalies now usually exceeds the magnitude of cool anomalies. What we can say is that global warming has an effect on the probability and intensity of extreme events. This is true for precipitation as well as temperature, because the amount of water vapor that the air carries is a strong function of temperature. So the frequency of extremely heavy rain and floods increases as global warming increases. But at times and places of drought, global warming can increase the extremity of temperature and associated events such as forest fires.
    That's not "propaganda", that's carefully-written and entirely reasonable explanation of the relationship between underlying trends and superimposed spatio-temporal heterogeneity.
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  21. #20 Ned at 22:33 PM on 8 September, 2010 In contrast, the occasional spatial or temporal cold anomalies (like parts of the US last winter) are best described as reminders of the climate we're leaving behind. They're not representative of what most places will feel like most of the time in 2020 or 2040 or 2060. Do you mean the recent cold spell in Bolivia, unprecedented in recorded history that emptied rivers there of fish and wreaked havoc on wildlife is supposed to be a reminder of the climate we're leaving behind? Sounds funny.
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  22. Did you actually read the article you linked to, BP? The existence of an anomalously cold winter in parts of South America is a fact, but there's actually a great deal of uncertainty about the specific event you're referring to and the relative importance of different causes. In any case, you apparently missed the point of my comment. Claiming that individual cold snaps in place X or place Y are somehow meaningful indicators of trends in climate is like claiming that individual cases of infant deaths here or there mean that we haven't made any progress on reducing infant mortality rates. Or like claiming that because your uncle Afred was a lifelong smoker and lived to be 92, smoking does not reduce life expectancy. Emotionalism isn't a very good substitute for reasoning, IMHO.
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  23. Or like claiming that because a birdie dropped from the leaning tower of Pisa flies away happily, dropping objects heavier than air does not necessarily make them fall down.
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  24. Not necessarily a very good analogy, BP, since the bird isn't just a statistical outlier from the same distribution as the rest of the heavy objects. Its behavior can be ascribed to obvious physical processes. Climate is very "noisy" at short spatial and temporal scales. Thus, one can almost always find some individual location that's abnormally cold at some particular point in time. Pointing to such areas may convey a misleading impression of long-term trends in global climate. I think my lengthy comment above provides a more useful framework for understanding things.
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  25. #24 Ned at 00:53 AM on 9 September, 2010 Its behavior can be ascribed to obvious physical processes I wonder if anyone were capable to implement a computational birdie model based on those obvious physical processes that could predict the trajectory of birdies dropped. Or even say anything meaningful on the statistical population of such trajectories.
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  26. By birdie do you mean something to do with golf? A model for predicting ball location based mostly variation of angle of strike and force? Okay, so there is wind and bounce too but this doesnt seem either difficult nor to involve an dynamical system theory either. Of course the theory wont help you get one...
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  27. As far as I can tell, BP's contributions to this thread consist of the following: * A lot of fish died in Bolivia. * Something unclear about a "birdie" dropped from the leaning tower of Pisa. The point of the first comment seems to be that the fish might have died because it was cold, and if it was cold in Bolivia recently then global warming isn't occurring. Or something like that. I have no idea what the point of the second comment is. Perhaps it's an attempt to illustrate the subject matter of this thread (chaos) by randomly posting irrelevant remarks and seeing where the discussion goes?
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