As one with just about exactly the right \"little knowledge\" of science to be dangerous - I have been wondering about the following.

According to the story I heard about the \"butterfly effect\", it was discovered when a climatologist had to interrupt a long climate model, so took a printout of values from one point in the middle of a run, and simply input those values to start another run when he could come back. He was shocked to see a different set of results come out, and upon further investigation, he discovered that the different pattern arose because the printouts were only displaying 8 digits while the internal memory of the computer was carrying the values to greater precision, and thus the values were different by very small amounts. I understand this to imply that very small differences in values like wind speed can have some impact on weather patterns.

The second consideration is simply thermodynamic - energy can not be created nor destroyed (as long as we understand mass as carrying the potential energy identified in Einsteinian relativity theory). As a very specific example, this would imply that a wind energy farm, that uses wind to generate electricity must be extracting at least some of the energy of the wind, presumably by reducing its velocity.

The question that I have is, given reasonable estimates of the efficiency of wind turbines, how much energy can we extract from wind before that would start to have effects on our weather.

Has anyone ever done even simplistic examinations of this kind of topic? If so, what kinds of results have they obtained?

Thanks for any answers you might have.

all the climatologists are on vacation! ;-)
your first paragraph presumably refers to Lorenz (he of the "Lorenz equations" and "Lorenz attractor" etc), as he discovered these accidentally:

http://www.geom.uiuc.edu/~worfolk/apps/Lorenz/
http://mathworld.wolfram.com/LorenzAttractor.html

as to the second paragraph, I imagine the size and energy cumulatively from wind is so much greater than what we can "take" from it that we're safe? It would be interesting to measure and compare with say, CO2 levels which we can see are from worldwide industrialization/autos/etc. I suppose in some "butterfly flapping its' wings" way that "robbing" some of the power from the wind in, say, a wind farm in Denmark would mean that something bad happens in China. But I'm a computer geek and not a "climatologist"!

> I imagine the size and energy cumulatively from
> wind is so much greater than what we can "take" from it that we're safe?

I think the energy taken from the wind by a natural windbreak of various sized trees and shrubs - which convert it mostly to white noise I imagine - would be much larger than that taken by a windmill. Either way, the real difference between wind and fossil fuels is that wind power converts energy which is already in the environment, channels it and eventually it gets released back into the environment. With fossil fuels, and nuclear fuels for that matter, the energy was safely locked up so burning it gives a net increase which is what drives the climate change.

Basically, climate change is caused by a change in the net energy in the system which is what drives it, caused by for example increased solar activity, increased greenhouse gases which reduce radiation back into space, burning of fossil fuels. But... You also have to include in the list things such as planting trees which also have an effect. Simply redistributing a constant amount of energy won't change anything, however many butterflies you have on the job.

Just wondering if Lornix did ever find this thread on the PHP board:

http://www.climateprediction.net/board/viewtopic.php?t=2401&start=0