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By Michael White | July 13th 2009 05:06 PM | 12 comments | Print | E-mail | Track Comments
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About Michael White

Welcome to Adaptive Complexity, where I write about genomics, systems biology, evolution, and the connection between science and literature, government, and society.

I'm a biochemist


... Full Bio

A good video laying out how climate scientists think:

There are problems that attract a different kind of thinker: really complex problems such as the human body, or an individual cell, or the climate system or solar physics. These are subjects that don't fit into the same aesthetic that special relatively fits into. They demand that you deal with multiple conflicting and intersecting elements. They are horribly non-linear right from the word 'go'; they are horribly complex. There is never going to be a theory of climate that somebody will come up with just by thinking about how the climate should work. People have tried, but they all fall pretty much at the very first hurdle. It is 'irreducibly complex'.

And you can't get away from that. You can't think that the climate is going to yield by just thinking about it. It needs to be thought about and measured and analyzed and thought about again and measured and analyzed and all of these disparate elements have to be brought in together. The reason climate models have grown up to be as complicated and as complex as they are, is not due to a lack of imagination. It's because that is how the real world is and that is the way the field has made progress. It hasn't made progress through people sitting in a room coming up with theories for how climate should work.

The field has made progress because people have made complex assumptions; they have built these things into models of varying complexity, all the way to the GCMs, (the big climate models that I was talking about earlier); they have been tested against very complex data from satellites, from intense observation campaigns, from in-situ observations.

Climate scientists take a lot of flak from the public for looking like they can't make up their minds. But these researchers have come up with some pretty smart ways of tackling such a tremendously complex system, and other researchers who build models of complex systems could learn a few things from the climate science community.



Comments

kerrjac's picture
The reason climate models have grown up to be as complicated and as
complex as they are, is not due to a lack of imagination. It's because
that is how the real world is and that is the way the field has made
progress.


Good quote that should be useful for any scientist.

But in wrapping up all of the field's complex complexities, you can't overlook the fact that public funding for climate science has *skyrocketed*. I guess politics is a factor in any scientific field, but it's especially prevalent in this one.

It's amazing how versatile the human mind is that one generation something which is considered complex is reduced to simple common knowledge. You might call this a form of human progress. (Reminds me of a babble I just wrote on simplicity vs complexity http://cntrly.blogspot.com/2009/05/complexity-vs-simplicityand.html).

However I do think that complexity should bring on skepticism. Perhaps in the short run it's an inevitable result of lots of great minds trying to solve a problem, but it should not persist in the long-run. Ptolemy, he was complex.

adaptivecomplexity's picture
However I do think that complexity should bring on skepticism. Perhaps in the short run it's an inevitable result of lots of great minds trying to solve a problem, but it should not persist in the long-run. Ptolemy, he was complex.

I'm not so sure it's a Ptolemy situation in this case - it's more like the situation where we have Newton's laws, but can't calculate anything more than the two-body problem. We know the basic chemical and physical laws of the material that makes up complex systems like cells and the atmosphere, and they are relatively simple.

Ultimately the issue is how can we deal with complex systems, in cases where we can't simply calculate what we want to know from fundamental principles. So the question is, are there simple, quantitative general principles of complex systems at higher organization which we could use? Not necessarily - there may not be any simple, elegant way to grapple with these systems, and then we're stuck with the messy tools we currently use.

kerrjac's picture
Interesting response.

I've less climate science knowledge, but I can't help but throw out my knee jerk reaction: If all the proposed answers are so messy, then might that be a sign that we're asking the wrong questions?

The stock market I think provides a useful analogy. As a phenomena, it's easily quantifiable, and the numbers can guide you, but there's no winning formula to reliably predict future stock prices. Such efforts at "technical analysis" will only take you so far -&even then it's considered more of an art than a science - but its limitations make complete sense: People own companies that are valuable; companies are valuable b/c they make products that people like; and there's no way to predict how much people will like x product over y amount of time, and even if there was, there'd be no way to discern the effect of the company's changing profit on its future stock price.

(Or consider other historical scientific dead ends, such as phrenology or astrology. Areas such as those failed not b/c the models weren't complex enough, but b/c they were barking up the wrong tree.)

Just b/c you have some #'s - be it temperatures or the dow - doesn't
automatically mean that you should be able to come up w/a complex model
to predict them.
Ultimately the issue is how can we deal with complex systems, in cases
where we can't simply calculate what we want to know from fundamental
principles. So the question is, are there simple, quantitative general
principles of complex systems at higher organization which we could
use? Not necessarily - there may not be any simple, elegant way to
grapple with these systems, and then we're stuck with the messy tools
we currently use.


You might try repeating those statements but instead of referring to climate, refer to any quantifiable aspect out of daily life, such as the number of times a human being sneezes in a year, the number of ants living in the world, or the number of leaves that will fall come November. In all of these instances you have well-established simple laws that can be synthesized to come up with a rough guesstimate, and if you're lucky a quantifiable amount of error in either direction. If there were a need to answer the latter questions with a greater amount of exactness, then certainly scientists could *try* to lead the effort. They might start by comming up with similiarly complex models.

Gerhard Adam's picture
If all the proposed answers are so messy, then might that be a sign that we're asking the wrong questions?

Bear in mind that it was weather prediction that lead to some of the early work in Chaos Theory, so it shouldn't be too surprising that even a deterministic system like the climate can be tough to get a handle on (for the long term).  The problem with weather is that you can never be precise enough to establish all the initial conditions that can influence the results.  The longer the time span you're trying to predict, the greater those slight inaccuracies are amplified resulting in major errors in long-term predictions.

When you're dealing with climate the problem gets even bigger because it's like trying to build a model that accurately predicts the weather over the entire planet for years .... so it's going to get messy and VERY approximate.  On the one hand, this makes some people say that the science is unreliable, so (depending on their political agenda), they want to blow off the concerns.  The flip side, is that Chaos Theory says that any turbulent system is subject to extreme reactions with even minor variations, so the concern of even slight warming trends is a real cause for concern because if the system degenerates into chaos, then the shift can be sudden and extreme.


The problem is that if the system does become chaotic, then no one can predict with certainty what it's going to do, other than be erratic, highly unpredictable, and probably not a lot of fun to be in.



adaptivecomplexity's picture
Bear in mind that it was weather prediction that lead to some of the early work in Chaos Theory, so it shouldn't be too surprising that even a deterministic system like the climate can be tough to get a handle on (for the long term).

Chaos theory and the weather make a great example of why, even if we know much about the system, it's extremely difficult to predict. Let's say you can describe a weather system with a set of 30 differential equations, and you know those equations are right, that they correctly capture the relationships between various components. There is still the matter of getting the parameters and input conditions right, and, as you say, in chaotic systems, small changes in parameters can make a big difference in behavior. Parameters and input conditions vary widely in nature. So even if we have a model with all of the correct equations, we still can't predict very well.

Hank's picture
Weather is a different animal; no one injects wishful thinking bias into weather projections (CNN producers do, maybe) but if a climate scientist takes 50 data points and then makes a numerical model and then makes a projection, that's a lot of room for error and if there is any bias at all, it gets magnified.   The problem is they don't like to lay out the details of models because they're worried what skeptics will do with it; they become the thing critics worried they have become.

In biology, nothing would ever get done if you sat around and worried what creationists would do with it.


Gary Herstein's picture
Weather is a different animal because being a chaotic system it lacks large scale structural stabilities.

kerrjac's picture
That sounds interesting. Any good modern books you might recommend on Chaos Theory?


adaptivecomplexity's picture
My favorite technical book is Nonlinear Dynamics and Chaos, by Steve Strogatz. If you like math, then you'll find this very readable.  My favorite popular book (and one of my all-time favorite science books) is Chaos, by James Gleick - one of the most exciting science stories I've ever read.

adaptivecomplexity's picture
You might try repeating those statements but instead of referring to climate, refer to any quantifiable aspect out of daily life,

Right, I don't mean to limit myself to climate science. But the complex systems we're talking about aren't quite the same thing as the # of leaves that fall or # sneezes. You're right that we have a well-established, simple concept that gives you a great estimate of those types of things - the Central Limit Theorem.

It would be fantastic if we could come up with something as elegantly simple as the CTL to understand the behavior of systems like a cell or the planetary climate. But there just may not be anything out there - you mention the stock market, and that's a good example. The behavior of some systems in nature may forever as hard to predict as the stock market - there is no reason that things must be captured by simple rules. We don't know yet.

Hank's picture
I don't think climate scientists deserve as much sympathy as they get here.   In biology, or in physics, no one circles the wagons around a hypothesis.    Mainstream journalism began to die 40 years ago when it became fashionable to do good works rather than journalism.    In the 1970s and on, the reputation of journalism was so partisan that most of the people who went into it were partisan; they weren't breaking form, like Walter Cronkite, that was their form.  Now look what we have as a result.  None of them can be trusted.

So it goes with climate science.    By vilifying the scientists who disagreed with one pet hypothesis in otherwise a solid theory, they have made it so most of the people who go into climate science next year will be interested in advancing the cause of CO2-based global warming and not science.  The IPCC did more of a disservice to science than Bush ever did by throwing all those who disagreed off the committee in 2001.    

Climate science would not be considered 'science' at all on this site if we used the same methodology and called it sociology; in too many cases it is conclusions drawn by people who are not statistical experts or proficient in numerical modeling of any kind.   In too many cases they are matching data to the topology they want.   

The competent climate scientists need to not engage in "well, we can't dispute X because he's on our side about global warming" thinking and instead side with taking back their discipline from the zealots.

adaptivecomplexity's picture
Climate science would not be considered 'science' at all on this site if we used the same methodology and called it sociology; in too many cases it is conclusions drawn by people who are not statistical experts or proficient in numerical modeling of any kind. In too many cases they are matching data to the topology they want.

I don't think that's true at all. The guys who do the major modeling (and there aren't that many groups) know their stats. In any field (and biology is no exception) you get people who don't know stats publishing bad stats. But I don't see any evidence that the major conclusions of the field are drawn primarily by people who don't know their math.

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