7 Billion and growing
The human species is constantly striving for growth - something must fuel it
The importance of the exponential function.
"The greatest shortcoming of the human race is our inability to understand the exponential function." - Dr. Albert Bartlett. Modern agriculture is the conversion of petroleum into food. So basically, no petroleum, no food. Petroleum is necessary to make fuel for the ships, planes, and trucks that import and export food. Machinery necessary to garden i.e. plows, harvester, spreaders, etc.