A first empirical comparison of energy Footprints embodied in trade -- MRIO versus PLUM

The Ecological Footprint as an indicator that accounts for human demand on global bioproductivity sets out to quantify the impacts associated with consumption in a given country, including the impacts associated with trade. The National Footprint Accounts (NFA) by Global Footprint Network (GFN) calculate trade-embodied Footprints by multiplying yield and embodied energy factors with mass volumes of traded goods in a "Product Land Use Matrix (PLUM)". This article compares energy Footprints embodied in trade from and to the United Kingdom in 2002 as calculated by the NFA-PLUM with the results from a recently developed multi-region input-output model (MRIO) for the UK. Although totals for imports and exports are comparable, breaking down the results by economic sectors reveals large differences and hardly any correlation between the two methods. The omission of trade in services (especially transport services) and upstream impacts of energy goods (fossil fuels) and the use of inappropriate embodied energy factors in the NFA-PLUM method are identified as the main reasons for these differences. In the light of the results it seems that a comprehensive Footprint account of trade can better be achieved with an input-output based approach. I conclude that MRIO models - once fully developed - will be particularly suitable in the future to estimate the Ecological Footprints of imports and exports of nations with the possibility to track their origin via inter-industry linkages, international supply chains and multi-national trade flows.