Not to mention the 'luxury' of feeding millions of people worldwide using fossil fuels.  

1930 - One farmer supplied 9.8 persons in the United States and abroad

1954 - Number of tractors on farms exceeded the number of horses and mules for first time

1960 - One farmer supplied 25.8 persons in the United States and abroad

There are now 751,000 farmers in the US.  

Today's American farmer feeds about 155 people worldwide.  

How will we feed the difference between 25.8 persons and 155 persons when we no longer use fossil fuels?   

Just let those 149 people per farmer starve?  We don't have the horses or oxen to even go back to the 1954 level of feeding people.   

We also can't get the food that is grown to the hungry without diesel trains and trucks and oil-fired ships.