An analysis of oranges transported to market in four US cities shows that fruit imported from farms thousands of kilometres away can have a smaller carbon footprint than fruit that travels much shorter distances.

Eric Bell and Arpad Horvath at the University of California, Berkeley, looked at the ‘cradle-to-market’ greenhouse-gas emissions of oranges that travelled from agricultural regions, including those in California, Florida, Mexico and Chile, to four destinations: New York City; Los Angeles, California; Chicago, Illinois; and Atlanta, Georgia. The authors found that how an orange travels to market can be a bigger factor in the size of its carbon footprint than the distance it covers.

That’s because oranges freighted from afar are often transported by container ships and trains, which can carry much larger quantities than trucks and use much less fuel per kilo of oranges. For example, oranges that travel from Mexico to New York by truck have a travel-related carbon footprint six times larger than that of oranges that travel from Chile to New York by container ship, even though the distance from Chile is more than twice that from Mexico.