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Wednesday, February 07, 2007

Chaos and the weather

The tone on the "Right" and the noises out of their Echo Chamber have been a bit shriller since the release last week of the report by the Intergovernmental Panel on Climate Change linking human activity to global warming. Last May I gave instructions on "How to be a Climate Change Denier":

1. Climate change? What "climate change"?
2. It's all a myth. Not happening.
3. And we had nothing to do with it, so there's no point in changing what we're doing.
4. Besides, people pay good money to travel to the tropics each year. Now they don't have to travel so far!

There have been some developments in these areas since then. #1 seems to have fallen out of favor, but it still gets dredged up once in a while. #2 has been refined to declare that the myth was invented by Al Gore (see the "ManBearPig" episode of South Park) to get attention, or by the Weather Channel to garner ratings. #3 is expanded to include every possible natural phenomenon that can influence the climate - trees that emit greenhouse gases, volcanoes, solar cycles, solar flares - and to seize on them as being the major, or even the sole, causes of climate change. #4...well, #4 is openly stated in an article in this year's Old Farmer's Almanac (which has been running annual articles by climate change deniers for the past few years). George Will tiptoes up to the point of saying it in his "Last Word" piece "Inconvenient Kyoto Truths" in this week's Newsweek:

Was life better when ice a mile thick covered Chicago? Was it worse when Greenland was so warm that Vikings farmed there? Are we sure the climate at this particular moment is exactly right, and that it must be preserved, no matter the cost?
There is a concept of a "tipping point", a point beyond which a system will begin to change at an accelerating rate without further input. Imagine putting a wooden board on a table so that it is hanging off a little. You can push that board out a little bit, and a little bit more, and a little bit more, and nothing much will happen - up to a point. Push the board just far enough and the mass of the board hanging off the table will equal the mass on the table - but the board will stay in place. A little bit further and it will begin to tip, but a degree of friction at the point of contact will keep the board from slipping off the table. A little bit more and the board will slip off the table. You can probably catch it, and drag it back, and reset the arrangement, if you're fast enough. Do that, because we'll be needing it in the next paragraph.

Now this time, line wineglasses up along the board. What happens when we reach the tipping point? Can you reset the wineglasses that smashed on the floor?

Reset the board, replace the broken wineglasses. Now add marbles, toy cars, cubes of Jell-O, a television or two, and a pack of marmosets. What happens when we reach the tipping point?

None of that has anything to do with what I'm about to say next.

I have a degree in Physics. I even did some time in graduate school. I was there to study Non-Linear Dynamics, the Physics of complex systems, known in popular literature as "Chaos Physics". I planned to have a Ph.D. by age 27 and use it to write books explaining complex Physics to the common layman. Things didn't exactly go as planned.

If you're interested in Chaos Physics, the best introduction I know of is James Gleick's book Chaos: Making a New Science. He's not a scientist, but he wrote the book after interviewing and working with a lot of people who are. In one of the earlier chapters he talks about the discovery that models of the interactions of air, land, and water that form the systems that determine our weather are irreducibly complex. That is, no matter how far down you measure data to determine the starting point for your models, there's always a level of precision below that that has an important effect. This is what's known as "sensitive dependence on initial conditions": start your calculations off using data that is precise to three decimal places, run your model for a certain period of time, and you will get one result. Start the same calculation using data with four decimal points of precision and run the model for the same amount of time, and you will get a different result. The longer you run your models - which are iterative models, where the results of cycle 1 become the inputs for cycle 2, and the results for cycle 2 become the inputs for cycle 3, and so on - the farther apart the final results will be. There is no practical level of precision that can be used to determine the inputs for meteorological models that can give results that are even marginally approximate for more than about three days out. Which is why I scream at the TV every time the weatherman gives a 5-day, or 7-day, or even 10-day forecast.

(One of the fun things with these equations is that if you start off with the right inputs you can create some really dramatic results. For example, there are lots of ways of throwing the system into a self-reinforcing Ice Age, and there are lots of ways of producing a permanent Greenhouse Effect. There are lots of ways that temperatures can flip-flop...well, chaotically. The inputs for these results are not always what you would expect.)

So, given that, is prediction hopeless when it comes to weather, especially long-term trends?

Well, to an arbitrary level of precision, yes. But meteorologists can look at trends, and records, and can compare where we are to where we've been. And computers can run thousands and hundreds of thousands of models of how the global climate will behave based on the best data available, with slight variations taken into account. These models can have their results polled and analyzed. If 99,999 out of 100,000 simulations say you're screwed, then you're probably screwed.

And that's the sort of analysis that went into the report that was presented last Friday, the same report that is saying that human activities are connected to Global Warming. The report that is being dismissed by non-scientists on the "Right" as being "not science." (Who would know better what is not science than a non-scientist?) But, really, did anyone expect them to admit that they have been wrong all along, that their delays in taking action prior to this point may have taken us beyond the point of no return?

That tipping point that I mentioned? The thought experiment involving the board, and the table, and the wine glasses, and the marmosets?

Icebergs are calving at rates not seen before. The ice caps are melting faster and faster. Things aren't just getting worse, the rate at which things are getting worse is accelerating. And human activities are pushing on the board, pushing it towards the edge of the table.

I think we passed that tipping point some time ago.

So we can try to save what wine glasses and marbles and Jell-O cubes and marmosets we can. Others will smash to the ground, beyond the point of repair. Maybe things have gone far enough that we can't stop the process.

Hang on. It's gonna be a hell of a ride.

6 comments:

whimsicalnbrainpan said...

That has always been my fear, that it is too late. Which is not to say that we shouldn't try and change our ways.

tiffany said...

sometimes i think i should never have children.
because, you know, if things get ugly--won't it be more bearable if i don't have to see my children suffer?

anyway.
that was way too depressing a thought for this early in the day. i think i better go check my myspace or something.

Ashley said...

I agree that was a bit depressing to read.
You should check out Jenni's fiance's live journal. He's a climateologist (sp?) and he usually has some good information about global warming. Although he hasn't posted too much lately because he's working on his masters.
livejournal.com/users/shadbolt75

Anonymous said...

I think we're clearly past some tipping point in the system. Average global temperature are displaying sharp increases. Good global assessments and looking at the behavior of things that integrate the effect of temperature over time (like glaciers) are key indicators of effect. Higher global temperatures (and receding glaciers) are proof that global warming has already taken place.

That leaves many questions: will it be short lived? are we the cause? it is bad? will it become a runaway event (and we all die)? what damage will it cause? can we take action to control it or circumvent the damage?

My short beliefs are not likely, yes, yes, no - buts lots of people will die, lots, and yes.

I am very pessimistic about any serious short term changes because we are so dependent upon fossil fuels. I don't think our collect imagination is up to it.

The problem I have with nay-sayers is that the evidence is so deeply multi-dimensional. Denying it is a bit like denying evolution. There is such an abundance of evidence, but their arguments seem to occur at the fringes. It is like saying the house isn't on fire because it hasn't burnt down yet. I've never heard one nay-sayer even say what might definition would be that defines a level of global warming they would call global warming. Is it +5 degrees? +10 degrees? How hot does the world have to be until you think it is getting hotter.

I once defended a study that appeared to hinge on a single highly statistically significant result. It was an excellent example of choosing the most sensitive endpoint for a study. When the issue arose that appeared as if so much hinged on this result, I pointed out that really every feature of the data showed the effect you would expect if the treatment worked like it was hypothesized to work. The data were wonderfully corralated, but we had the vision to pick the most sensitive measure of effect.

The nay-sayers are like tobacco lawyers and statisticians say that the study only shows it is 99% likely that smoking causes cancer. Hence, you can't prove that so and so really died from smoking.

Unfortunately, many people will always choose to look away from evidence that goes against their self interest or personal beliefs.

Super G

D.B. Echo said...

"It is like saying the house isn't on fire because it hasn't burnt down yet."

That is brilliant. That sums it up, right there. Did you just make that up? 'Cause I didn't get any hits on that phrase on Google, so I'm thinking you just made that up. You totally own that phrase. It makes me want to do a post that says "SuperG Hits One Out of the Park." Brilliant!

Anonymous said...

Ha ha ha - no I've haven't heard the phrase used before - but feel free to use it without reference.

Good luck w/Chris.

George