On May Day 2000, I participated in a “guerrilla gardening” action in London, digging up Parliament Square to plant crops. It was a utopian gesture—one of many made in those years by people opposed to the so-called Washington consensus—intended to reveal a glimpse of the beach beneath the street. I remember watching a man shin up a statue of Winston Churchill with a strip of turf and drape it over the old boy’s head to give him a mohawk. Shorn of political context, the image now appears on postcards.

Deep ecology, localism, and opposition to genetically modified food were…