Analysis of air pollution impacts resulting from freight transportation shifts due to Panama Canal expansion

December 17, 2012
Media contact: Erin Geoffroy,, 512.691.3407
Expert contact: Elena Craft,, 512.691.3452

(Austin, Texas, Dec. 17, 2012) Environmental Defense Fund (EDF) today announced the release of a peer-reviewed report, titled “Panama Canal Expansion: Emission Changes from Possible U.S. West Coast Modal Shift,” in a special issue of the journal Carbon Management. The report is a collaboration of scientists at the School of Marine Science and Policy at the University of Delaware and EDF transportation analysts.

The report focuses on the environmental opportunities presented by the expansion of the Panama Canal for the intermodal container shipping industry, and features a case study comparing estimates of carbon dioxide (CO2) and non-carbon dioxide emissions from Asia-U.S. cargo routes. The report evaluated whether a modal shift of east coast-bound cargo onto larger ships through an expanded canal offers net emission reductions compared with the land-freight truck/rail network via the west coast.

As ocean transport is more carbon efficient than truck or rail, it is expected that the use of larger ships and more water routes will reduce the CO2 footprint of freight transported through an expanded canal. However, the authors found that diverting cargoes from transportation modes with higher emissions per ton-mile, or the emissions released by moving one ton of freight one mile, may not provide emission benefits in this scenario. When taking future cargo volumes into consideration and assuming a 10 percent diversion from the west coast to the east coast, the effects of the expansion on CO2  emissions appear to be negligible due to longer distances traveled.

“While infrastructure investments like an expanded Canal will help shipping shift to lower-emission vessel designs, the multimodal supply chain must be considered a system to fully realize the sustainability benefits of freight innovation,” said Dr. James Corbett, Professor of Marine Policy at the University of Delaware. “We look forward to helping all parts of the freight sector – industry and policy decision makers – visualize the potential for green freight networks.”  

Changes in emissions of criteria pollutants could be regionally significant for air quality due to the localized nature of their environmental and health impacts. The model used in this analysis estimates a 17 percent increase in particulate matter (PM) emissions and an 18 percent increase in nitrogen oxides (NOx) emissions for East Coast routes, with associated reductions for west coast routes. Short sea shipping, the movement of cargo by sea that does not involve crossing the ocean, can potentially mitigate emission increases in regions with higher container traffic volumes. Therefore, system-wide and intermodal consideration is crucial to improve freight transport from origin to destination, not just from port to port.

“As greenhouse gas emissions from freight transportation are expected to increase 25 percent by 2030, this paper plays a critical role in presenting data that focus on the emissions implications of evolving trends within the shipping industry,” said Elena Craft, PhD, a Health Scientist at EDF.

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