“When humans took up farming, they became more disruptive still. According to the paleoclimatologist William Ruddiman, the adoption of wet rice cultivation in Asia some five thousand years ago may have released so much methane into the atmosphere from rotting vegetation as to have changed the climate. “A good case can be made,” he suggests, that “the people in the Iron Age and even the late Stone Age had a much greater per-capita impact on the earth’s landscape than the average modern-day person.”
