J. Environ. Econ.Manag. http://doi.org/h5j (2012)

Greenhouse-gas emissions from international trade come not only from producing the goods exchanged, but also from transporting them between countries. Largely overlooked, international transport emissions may change the ranking of countries by emissions per dollar of trade.

David Hummels of the University of Oregon, USA, and colleagues collected data on worldwide trade by transport mode — maritime, land and air — to estimate the amount of greenhouse-gas emissions associated with production and international transportation of traded goods from 23 sectors in 2004. They find that international transport is responsible for 33% of worldwide trade-related emissions, and over 75% of emissions for major manufacturing categories. They also discuss whether considering transport emissions increases the overall level of emissions from trade and illustrate how importing goods from low-emission producers can decrease a country's emissions, in the case of efficient transport.

Finally, they show that with full liberalization of tariffs and growth in gross domestic product concentrated in China and India, transport emissions grow much faster than the value of trade, due to trade shifting toward distant trading partners.