Last week, we looked at New York Times columnist Mark Bittman’s argument that “It’d be even better, really, if most of [our food] came from within a few hundred miles of where we live.” We were skeptical that Bittman’s “locavore” ethics were good for consumers or the environment, and it seems we had good reason to be. Steve Sexton, writing at the “Freakonomics” blog, estimated the increased costs of a locavore world on people and the environment. Sexton argues that local food ethics are based on false premises that fail to note the gains from comparative advantage and scale economies.

He writes:

Implicit in the argument that local farming is better for the environment than industrial agriculture is an assumption that a “relocalized” food system can be just as efficient as today’s modern farming. That assumption is simply wrong. Today’s high crop yields and low costs reflect gains from specialization and trade, as well as scale and scope economies that would be forsaken under the food system that locavores endorse.

Sexton’s estimates are more staggering than his arguments, which rely on widely accepted economic theory about the division of labor and efficient production. He estimates that “a locavore-like production system would require an additional 60 million acres of cropland, 2.7 million tons more fertilizer, and 50 million pounds more chemicals.” We knew modern industrial agriculture had strong economies of scale, but the degree of efficiency in modern agriculture is notable. The land saved by doing things the non-locavore way, by Sexton’s estimate, is larger than the total land area of Utah.

So locavorism may not be wonderful for preserving wild lands or green space, but it’s at least less carbon-intensive, right? Wrong. Sexton cites a Harvard economist who suggests that “going local” would not reduce emissions from transportation (the supposed environmental justification for the “100-mile diet”). That doesn’t even include any emissions from producing an additional 2.7 million tons of fertilizer and 50 million pounds of chemicals, or the emissions from the tractors and combine harvesters tending additional farmland.

Reducing the land-productivity of agriculture is bad not only for the environment but also for people. Sexton says that “experts estimate that in the next 50 years, the global food system likely needs to produce as much food as it did in the previous 10,000 years combined.” It is only thanks to agricultural innovators like the late Norman Borlaug that Sexton can write, “From roughly 1940 to 1990, the world’s farmers doubled their output to accommodate a doubling of the world population. And they did it on a shrinking base of cropland.”

With the world’s population passing 7 billion on its way ever higher, now is not the time for trendy activists and first-world foodies to “turn back the clock” on agriculture. The world’s poor can’t afford it.