I've come up with a simple formula that allows converting body weight to the corresponding weight of dry ice (CO2) sequestered by an individual. The magic factor is an astonishingly simple factor of 2/3. The conversion factor is irrespective of weight units (lbs or kilos). I derived the number as follows:
The human body contains 18% carbon by weight, meaning that 100 pounds of body weight contains 18 pounds of carbon. To convert to corresponding pounds of carbon dioxide, I multiplied by a factor corresponding to the increase in mass when carbon "burns" to carbon dioxide = [12 + 16 + 16]/12 = 3.67* This is also just the molecular weight ratio of CO2 to carbon.
These two factors, .18 x 3.67 = 0.66, which is very close to 2/3. That factor, (2/3) multiplied by body weight, gives the corresponding weight of a block of CO2 which all the carbon sequestered in a body would form.
So how much carbon do American adults sequester en mass? The average American male weighs about 190 lbs and the average American female weighs about 150 lbs. Using a 50/50 ratio for males to females and figuring that about 80 % of Americans are aged 15 and up (i.e., neglecting children), I estimate the total amount of carbon dioxide sequestered by the American adult population of 307 M people as follows:
307 M x .80 = 245 million adults. It follows that American men sequester:
245 M/2 x 190 x 2/3 /2000 = 7.8 M tons of CO2; and
American women sequester:
245 M/2 x 150 x 2/3 /2000 = 6.1 M tons of CO2. I converted from pounds to tons using the factor 2000 lbs = 1 ton.
American adults sequester approximately 14 million tons of carbon dioxide. That's got to be on par with a decent-sized forest. Note that men sequester more than women because they are heavier and have more carbon. Obviously Americans -- considered the heaviest of humans -- sequester the most carbon per capita worldwide.
OK, have at it!
*Lavoisier famously showed that metals increase their mass when they burn to their oxides, thus destroying phlogiston theory. I'm showing the same thing here by considering carbon to be like a metal and carbon dioxide to be like a metal oxide.