"All that is grassy is not green," begins Glaeser, in his most recent attack on planning efforts to implement large-scale metropolitan farming, which he believes "will do more harm than good to the environment."
"While neighborhoods benefit from the occasional communal garden, it is a mistake to think that metropolitan areas could or should try to significantly satisfy their own food needs. Good environmentalism is smart environmentalism that thinks through the total systemic impacts of any change. Farm land within a metropolitan area decreases density levels and pushes us apart, and carbon emissions rise dramatically as density falls."
Additionally, he cites a study which found that growing certain crops or livestock less suited for a given climate significantly increases the amount of greenhouse gas emissions and fertilizer required for growing, to the point where it is actually more environmentally friendly to grow where it is most suitable and then have the products shipped over long distances to consumers.
Thanks to Scott Ulrich