Joel Cohen
Mathematical Biologist, Rockefeller University
03:00

A Handy Example of Human Wastefulness

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Of Earth’s ice-free land, we have about 130 million square kilometers to work with, about 8% of which goes to creating foods that go directly to humans while another 30% is spent making food for farm animals—a population expert explains.

Joel Cohen

Joel E. Cohen is a mathematical biologist and Professor of Populations at Rockefeller and Columbia Universities. His research deals with the demography, ecology, epidemiology and social organization of human and non-human populations and with mathematical concepts useful in these fields. The author of 14 books, he has been honored with numerous awards, including the Sheps Award from the Population Association of America, the Distinguished Statistical Ecologist Award, the Tyler Prize for Environmental Achievement in 1999 and the Mayor's Award for Excellence in Science and Technology from the Mayor of the City of New York, Michael R. Bloomberg in 2002. Professor Cohen has been elected to the National Academy of Sciences, the American Academy of Arts and Sciences and the American Philosophical Society. He lives in New York. 
Transcript
QuestionHow much of our available land do we use in creating food

Joel Cohen: Well, the ice-free land of the earth, you know, the world is mostly water, like about 71% water, and 29% is land. Now, some of that land is under ice, Antarctica and Greenland, so let's put that aside. If you're only dealing with the ice-free land, it's about 130 million square kilometers, okay? Of that, humans use 38% for agriculture. So almost two-fifths of the entire surface of the earth is now devoted to making food for you and me, and 6.8 billion other human beings. That's a huge chunk of the earth's surface for humans to be manipulating. 

Of that 38%, I'm going to divide it into 2 pieces, 8% and 30%, okay? The 8% grows cereal grains for humans to eat, that go into human mouths—rice, wheat, corn, and then other grains also, okay? The 30% feeds our domestic animals. So the way we use the land, we're using 30% of the entire land area of the earth free of ice to feed our domestic animals. And of the cereals we grow, one-third goes into the mouths of animals and about half goes into human mouths, and about one-sixth goes into the mouths of the machines, our pets, for bio-fuels, and for starches and for other industrial uses. 

So we can say that the production of food by humans has had a huge impact on the use of land on the earth, on the extinction of species due to burning of forests and change of grasslands by animals. And if you look at the amount of energy that the domestic animal populations consume, it's about twice that that all humans consume. So even though we consume a lot, our domestic animals consume about twice more. 

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