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Jared, you wrote:
"And that's the point. The earth's spin rate CAN be changed, and there  are
environmentalists suggesting that we're already changing it or bordering  on
changing it."

We have changed it. No doubt about it. But the change  is miniscule. Huge
reservoirs created in mid-northern latitudes especially have  moved a significant
amount of mass closer to the Earth's axis of rotation  (poleward). But this
change in rotation rate is almost certainly unmeasurable  and in any case would
be masked by much larger natural changes. The big loop  current in the Gulf
of Mexico this summer (the one responsible for "cooking"  Katrina and Rita into
super-storms) piles up more water in one place than most  any of those
reservoirs. Here's a GIF of the beast from the end of  August:
http://www7320.nrlssc.navy.mil/global_nlom32/navo/GOM1UV/TOPEX+ERS2+GFO+MOD_SS
HUV_GOM1UV_20050831.001.gif
This  map is showing sea surface height. It's over half a meter higher than
the rest  of the Gulf at the center of that swirling eddy. By the way, the
above URL  should be all one line. I expect it will be split up in transit.

And:
"So, let the billion chinese sneeze instead of throwing rocks. OK?  Plain
thrust
vector, a billion weak rocket engines."

That still won't  work. The air "catches" the sneeze and rather quickly
transfers that momentum  back to the Earth. Unless they sneeze above escape
velocity.

And:
"The point being, a sufficiently motivated civilization could easily change
or
standardize the spin rate of their planet, if they had any desire to do  so."

Yes. I agree. It's merely a matter of money. But I suspect any civilization
with sufficient wealth to micro-manage their planet's rate of rotation  will
find better ways to spend their time! 

-FER
42.0N  87.7W, or 41.4N 72.1W.
www.HistoricalAtlas.com/lunars

   

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