We are in the midst of a great migration to cities.  The number of farms and people engaged in agriculture continues to decline.  Yet human ingenuity has produced abundant resources of food, through innovation and technology.  

Historically, when disaster has struck and we have been threatened as a species, we’ve always seemed to find a way out, particularly with respect to our food supply.  This has resulted in increases in population, which then takes us to the next crises.

This cycle is replicated throughout history.  It is what MacArthur fellow and Columbia Professor, Ruth DeFries calls a cycle of Ratchets, Hatchets and Pivots.  She explains in her book The Big Ratchet: How Humanity Thrives in the Face of Natural Crisis.

My conversation with Ruth DeFries: