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?

  • $\begingroup$ 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

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.)

| cite | improve this answer | |
  • $\begingroup$ 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

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.