Fig. 5.

Number of years of phytomass food potentially available to feed the global human population. Calculated from the total stored phytomass energy of the planet divided by the metabolic energy needs to feed the global population for 1 y (i.e., joules/joules per year = years) assuming an 8.4-MJ per capita daily diet for the entire year. Rapidly decreasing trend line indicates increasing dominance of phytomass by humankind. For reasons given in the text, these values are very conservative. Little margin remains to safely continue the current trend.