Here’s an article from Landscape and Urban Planning making a connection between urban agriculture and greenhouse gas emission reductions. It makes sense – any food that comes from nearby will reduce transportation energy use, air pollution, and carbon emissions. We could either decide to do this for ethical reasons, or we could build more of those external costs in the price. It probably makes sense to do some of each.

The expansion of urban agriculture assists in reducing greenhouse gas (GHG) emissions not only by producing food but also by reducing the amount of food transported from farming areas and therefore reducing the food mileage. This study seeks to estimate “the expected GHG reduction effect” in the case of a revitalization of urban agriculture. For this purpose, this study first calculated the area available for urban farming by targeting the metropolitan area of Seoul and then calculated the production per unit area by focusing on “the crops suitable for urban agriculture”. Using this estimated value, the study estimated crop production, the resultant food mileage decrement, and the reduction of carbon dioxide (CO₂) emissions that could be obtained if the Seoul metropolis introduced urban agriculture. The results estimated that if the Seoul metropolis implemented urban agriculture in a 51.15 km² area, it would be possible to reduce CO₂ emissions by 11.67 million kg annually. This numerical value is the same amount of CO₂ absorbed annually by 20.0 km² of pine forests and 10.2 km² of oak tree forests that are 20 years old. From the perspective of GHG reduction effects in the transportation sector, urban agriculture is expected to produce a considerable effect in diverse aspects such as the habituation of green growth, self-sufficiency, and food security.