Have you swallowed the 'Computer Model' lure as well as the hook, line and sinker?

Question

Computer models break down with the number and uncertainty of parameters. Climate models have MANY parameters that are VERY hard to quantify. This is why weather models break down rendering weather predictions of more than a few days unreliable.

http://www.americanthinker.com/blog/2007/10/science_earth_climate_is_too_c.html

So, Dana, you think it is remarkable that computer models fit the data? Of course they fit! That is the data that was used to construct the model in the first place. That is called "backfitting".

You should learn the science of computer modeling, data sampling and statistical analysis if you are going to use those very things to affect policy.

Bob, the models work for airplane design because the parameters are known, few and very quantifiable. Climate models, on the other hand, have more parameters and these parameters are weakly understood wrt causes and affects.

You've got it, Vlad! Seems like the models are only a suggestion. You've got to build it and see what happens.

Jablob,

"Digital modeling is not some sort of alchemy. Theoretical science is based on mathematics" You'd think that.

"Mathematics is internally consistent and irrefutable." Not true--at all.

Answer 1

Anyone can take snippets of complex issues out of context and spin it any way they like.

Digital modeling is relatively new. However, humans have been using analog modeling since the dawn of time; the sundial, Stonehenge, mechanical clocks, the abacus, mechanical calculators and the Antikythera mechanism are examples.

Early computer models of the climate were able to show the direction of the change and some hints at the magnitude, and confirmed earlier theoretical predictions. Later models confirmed the trend and narrowed the range of uncertainty. Surely models are imperfect and are constantly improving, but this is not the point. As different investigators approach the problem with different computational methods, the different models all show the same trends and general outcomes. As greenhouse gasses increase, average temperature increases. Warming will be greater at the poles and at night. As atmospheric moisture increases due to the ability of warmer air to hold more moisture, precipitation events will become more intense. These effects are occurring now exactly as the models predicted.

Digital modeling is not some sort of alchemy. Theoretical science is based on mathematics. Mathematics is internally consistent and irrefutable. A theoretician uses mathematics to prove that his theory is internally consistent. The theory may have no practical application at this point, but it is a valid framework for further study and application. Newton remains a giant because the calculus he invented has endless applications. Empirical scientists design experiments to test the theory. After the theory and the mathematics have been proven to be correct by direct measurement through experimentation, the same mathematics from the theory is used to design the model. Models are used to design nuclear weapons, chart spaceflight, model astrophysical phenomena like star and galaxy lifecycles, model particle interactions in nuclear physics, model biochemical reactions for the design and efficacy of drugs, model population growth, model economic systems, model thermodynamic systems for combustion and engine design, model material behavior for structural design, and more I haven’t thought of. The point being that the models aren’t “tweaked to get the answer you want”. They are used every day around the world by scientists and engineers to make things that work.

Computer modeling has opened a new chapter in science. Empirical scientists were once limited by that which they could construct and observe. Now we can take models, which are proven to be internally consistent because they arrive at the same results obtained from direct measurement, and drive them beyond the directly obtainable. We can drive them into the future, into the past, speed them up, slow them down, enter parameters that would be unrealistic or uneconomic or impossible for a researcher with practical constraints. Sometimes the models produce nonsense. Sometimes they produce results that the researchers are unable to explain, and thus open a new field of inquiry. It is a new frontier.

It amuses me that people use weather models as proof they are no good. “We can’t predict the weather next week, who is to say what will happen in 100 years?” The point is we can predict the weather next week with some accuracy. We can predict the weather tomorrow within a degree or two of temperature and an hour or two of when the precipitation will arrive. That is an incredible achievement.

edit:
Interesting. How is it that all the things designed with computer models work? What is theoretical science based on? And which part of mathematics is refutable? Seriously dude, you got one up on Newton and Gödel.

Answer 2

I think they did a neat trick when they switched "model" for "simulation". Yes while computer simulations are used in the design of a lot of tech now. They always seem to want to test at least a scaled down version in a wind tunnel or water tank first before they go on with real life concepts.

Answer 3

This is somewhat true. Where it cannot predict the daily temp down to a degree, it can predict trends based on past and current weather patterns. And thats all they are really doing.

What computer models and science cannot do is tell us what the weather was like a million years ago. They can get a "median temp" over a few centuries, but nothing that anyone would really put their life on the line for.

Answer 4

Apparenlty many have. What they don't realize is that even today's super computers still do a very lousy job of modeling things like ocean currents, winds, and moving gasses.

None of which have anything to do at all with global climate models.

Answer 5

People have a choice. They can believe a right wing political site. Or they can believe scientists:

http://environment.newscientist.com/channel/earth/climate-change/dn11649

Computer models are used to design the planes you fly in. They have been used in historic mathematical proofs:

http://www-history.mcs.st-andrews.ac.uk/HistTopics/The_four_colour_theorem.html

This argument is political, not scientific. The fact that it's being circulated by computer is, however, very amusing.

Answer 6

Once Venus the line hit me side the head but there was no hook on the end of it.

Answer 7

Actually you've got it exactly backwards. The fact that there are so many parameters makes it amazing that the climate models have matched the temperature record over the past century this accurately:

http://en.wikipedia.org/wiki/Image:Climate_Change_Attribution.png

And thus proves that the AGW theory is very likely to be accurate.