We still haven’t reached peak oil . But peak milk happened in 2004, peak soybeans in 2009, and peak chicken in 2006. Rice peaked in 1988.

A new study published in Ecology and Society explains that 21 key resources that humans rely on–mostly food–have already passed their peak rate of production.

“Peak,” in this case, doesn’t mean that we’re actually producing fewer chickens or less milk yet. Instead, the researchers looked at the fact that the rate of production has plateaued, at the same time that population is increasing.





“We wanted to develop something like early warning signals,” explains Ralf Seppelt, a researcher from the Helmholtz Centre for Environmental Research in Germany, who worked on the study with colleagues from Yale University and Michigan State University.

“We approached the whole thing with an open mind,” he says. “We didn’t want it to be apocalyptic. We tried to seek patterns that give reliable information about how we really harvest the Earth, knowing that no one really wants to experience the time when the whole thing plateaus.”





The researchers analyzed production rates over time for 27 key resources, including some fossil fuels. But while they found that nonrenewable resources like coal, oil, and gas haven’t peaked, most foods have.

“We were actually surprised to find so many peak year signs–surprised that this is such a consistent pattern happening in the last 10-20 years,” Seppelt says.