Claims that local food production cut greenhouse gas emissions by reducing the burning of transportation fuel are usually not well founded.

Transport is the source of only 11 percent of greenhouse gas emissions within the food sector, so reducing the distance that food travels after it leaves the farm is far less important than reducing wasteful energy use on the farm.

Food coming from a distance can actually be better for the climate, depending on how it was grown.

For example, field­-grown tomatoes shipped from Mexico in the winter months will have a smaller carbon footprint than local winter tomatoes grown in a greenhouse.

In the United Kingdom, lamb meat that travels 11,000 miles from New Zealand generates only one­-quarter the carbon emissions per pound compared to British lamb because farmers in the United Kingdom raise their animals on feed (which must be produced using fossil fuels) rather than on clover pastureland.

When food does travel, what matters most is not the distance traveled but the travel mode (surface versus air), and most of all the load size.

Bulk loads of food can travel halfway around the world by ocean freight with a smaller carbon footprint, per pound delivered, than foods traveling just a short distance but in much larger(→smaller) loads.

For example, 18­-wheelers carry much larger loads than pickup trucks so they can move food 100 times as far while burning only one­-third as much gas per pound of food delivered.