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Jolantru
When sea level is measured is displacement caused by sea going vessels or sunken vessels taken into account?

 
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Sea level is measured for what it is, not what it should be if exceptions were taken in account. It is generally expressed as "mean sea level", meaning the approximate average if the oceans were completely still and tides averaged.

Accounting for floating or sunken man-made objects would compare to the displacement caused by a tiny pebble in an Olympic-sized swimming pool. You may argue that it is measurable. True enough, but the result is negligible and no useful purpose is served from these mathematical gymnastics. Compound these calculations with people are jumping into and climbing out of the pool and they become virtually impossible. Expand this example to a global scale and the futility becomes clear. Especially when you take into account such extreme examples as the Bay of Fundy exhibiting as much as a fifty-five foot difference between high and low tide.

Fanatics blame humans for so-called "Global Warming" that will melt the ice caps. They wail that sea level will rise by hundreds of feet in the near future and we must stop burning fossil fuels that cause the problem.

Not so. Tide gauges around the world indicate a rise in mean sea level of a mere eight inches during the entire 20th Century. Measurements from year-to-year vary widely, but they follow a reasonably steady trend line approximating a 2 millimeter increase every year. The 100-year net result merits little serious interest. If this continues at the current rate, 1,500 years will pass before mean sea level increases ten feet.

If your car only gets 12 miles per gallon, you need not fret excessively over the global impact. Consider, instead, the impact on your wallet.

Comments from Jolantru:
I am very impressed by the simplicity of the answer, I think anyone could understand it. Also the details are interesting and help create a clearer picture.
Mr Craig Brownell
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I recently heard on Discovery or somewhere else relatively reliable that the volume of water in earth's oceans is equal to the volume of earth's moon.

That makes the displacement of ships so small as to be immaterial, probably smaller than our measurement uncertainty.

We used to call that "bugdust"!

robdashu USA
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