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There are 7.614 billion humans and counting. On average a human being consists of 60% water. With that water being locked away from natural circulation for an average of 80 years. Are there any adverse effects this could have on global weather patterns?

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  • $\begingroup$ You assume that if the water wasn't "locked away" in human bodies that it would not be locked away in some other place instead. Why? $\endgroup$ – Solomon Slow Apr 11 '18 at 14:19
  • $\begingroup$ Total volume of all of the human bodies on Earth is less than one billionth of the total volume of all of the world's oceans. $\endgroup$ – Solomon Slow Apr 11 '18 at 14:20
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Humans are not locking up water. You can use mass conservation and Kirchoff's first law (where you replace charge with water) to see why: if water was accumulating in human bodies, they would tend to get bigger. Over the span of a year a human consumes somewhere around half a ton of food and water, yet our weight usually doesn't go up that much per year.

Second, the total mass of all human water is on the order of ($7.2\times 10^9$ people)(62 kg)(65% water) =$2.9\times 10^{11}$ kg. This is a bit more than the water stored in the London storage reservoirs (0.2 km$^3$), nothing significant globally when you consider real lakes, rivers and seas.

(Atoms that get integrated in DNA in long-lived cells like neurons are taken out of circulation for a few decades, but the total mass is tiny.)

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  • $\begingroup$ Humans do get bigger over time. We are born 8lb grow 180lbs in the fisrt 22 years. Some more some less. Kirchoff's first law?? $\endgroup$ – jpmh78 Apr 12 '18 at 22:32

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