World Econ. http://doi.org/kfq (2013)

Carbon dioxide emissions from international freight and passenger transport only amounted to about 5% of global energy-related emissions in 2001. However, this fraction is likely to rise due to growing international trade, and the increasing use of more carbon-intensive air transport to move goods across borders.

Frank Vöhringer of the Ecole Polytechnique de Lausanne, Switzerland, and colleagues analysed changing patterns of carbon emissions from international transport worldwide by looking at different trade and climate policy scenarios. They found that if international cooperation leads to trade liberalization, with no climate policy enforced, about half of the increase in world emissions is due to international transport. If international cooperation includes trade and climate policies (carbon taxes), trade-related emission sources become less important, but emissions from international transport increase regardless of the carbon tax coverage. In particular, if a carbon tax is imposed only on rich countries — excluding air and water transport from the tax base emissions from international transport increase by 11.6%. Assessments of trade and climate policies should therefore consider international transport emissions.