Occasionally, to give myself some science/math challenge (beyond the last page of Make magazine), I like to attack a multidisciplinary problem that is (a) completely inappropriate for a man of my education, and (b) has probably already been done by someone with the appropriate education.
A recent “Believe it or not” cartoon led me to data that: of the fresh water in the world only 0.3 percent is surface water which I verified(?) at Wikipedia.com along with the fact that two-thirds of [fresh water] is frozen in glaciers, I started to wonder about how much water the human race contains and where, in relation, that water is (or is going to come from). I wonder about the noise made that the polar ice caps are melting, and I wonder how the volumes and ratios of population growth and polar ice cap melting align, since the water in a living body is stably “trapped” in itself and therefore removed from the global cycle of water circulation.
The pertinent data I can come up with is that the human body is about 60% water in adult males and 55% in adult females, that the sex ratio is commonly assumed to be 105 boys to 100 girls but the current world wide sex ratio at birth is 107 boys to 100 girls. Also, I found data on world population history that I can use to calculate the amount of H2O mass “trapped” in humans. To get conservative figures, I assumed that the average human mass is 60 kg and applied the 100/105 ratio.
1800 1850 1900 1950 1999 2050 2150
World Pop. 978 1,262 1,650 2,521 5,978 8,909 9,746 F. Water 15,743 20,315 26,561 40,582 96,231 143,413 156,887 M. Water 18,033 23,270 30,424 46,485 110,228 164,273 179,707 Total H2O 33,777 43,585 56,985 87,067 206,460 307,686 336,594 Delta H2O 29% 31% 53% 137% 49% 9%
(population in “millions”; mass in Mg)
So I can show the amount of water in humans is currently over 307 metric tons, and the change in that amount over the last 5 decades is an increase of 50%.
I’ve found charts about the rate change in the polar ice caps, but I can’t find anything with actual numbers. Anyone know what that is? or does anyone have arguments about my approach?
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