Integrated Economic and Physical Information for Environmental Footprint Modelling

A nation’s consumption of goods and services causes various environmental pressures all over the world due to international trade. We use a multiregional input−output model to assess three kinds of environmental footprints for the member states of the European Union. Footprints are indicators that take the consumer responsibility approach to account for the total direct and indirect effects of a product or consumption activity. We quantify the total environmental pressures (greenhouse gas emissions: carbon footprint; appropriation of biologically productive land and water area: land footprint; and freshwater consumption: water footprint) caused by consumption in the EU. We find that the consumption activities by an average EU citizen in 2004 led to 13.3 tCO2e of induced greenhouse gas emissions, appropriation of 2.53 gha (hectares of land with global-average biological productivity), and consumption of 179 m of blue water (ground and surface water). By comparison, the global averages were 5.7 tCO2e, 1.23 gha, and 163 m blue water, respectively. Overall, the EU displaced all three types of environmental pressures to the rest of the world, through imports of products with embodied pressures. Looking at intra-EU displacements only, the UK was the most important displacer overall, while the largest net exporters of embodied environmental pressures were Poland (greenhouse gases), France (land), and Spain (freshwater). ■ INTRODUCTION Among the many environmental concerns the global community will be faced with in the 21st century, three major challenges stand out as particularly important. First, considerable efforts are currently directed toward the task of minimizing anthropogenic greenhouse gas (GHG) emissions and the potential harmful climate change effects caused by them. Furthermore, the rapid growth in population and material wealth over the previous century has led to widespread concerns about the state of two resources of vital importance to all life on earth: freshwater and biologically productive land. These three areas of concern are all highly important, and, though essentially different, they are all interconnected and mutually influencing each other, and direct efforts to alleviate one problem might well imply hidden trade-offs with others. As such, it is reasonable to suggest that these (and ideally other) environmental challenges should be assessed simultaneously when politicians and leaders are shaping policies and making investments with a sustainable future in mind. However, assessing the environmental impacts of GHG emissions and human appropriation of land and water at the macro level is nontrivial, and several approaches exist. Based on the argument that environmental pressures are ultimately driven by consumption of goods and services, several studies and pressure indicators follow the principle of consumer responsibility and attempt to allocate full life-cycle environmental responsibilities of purchased commodities to final consumers. As a way to communicate this idea to a wider audience, the “footprint” term has been adopted for various quantitative measures of environmental stress that adhere to the principle of consumer responsibility. Galli et al. define a “Footprint Family” of three of the most well-recognized footprints available, to be used in assessments of the three environmental issues discussed previously. The Footprint Family includes the carbon footprint (CF), the Ecological Footprint (EF), and the water footprint (WF). The carbon footprint is a measure of total GHG emissions embodied in consumption, measured in tons of CO2-equivalents. 3 The Ecological Footprint quantifies embodied biological resources in terms of required area of biologically productive land. The measurement unit is the global hectare (gha), which is defined as a hectare of average productivity. Finally, the water footprint measures direct and indirect freshwater requirements in m, Received: May 15, 2012 Revised: September 10, 2012 Accepted: September 26, 2012 Policy Analysis pubs.acs. org/est © XXXX American Chemical Society A dx.doi. org/10.1021/es301949t | Environ. Sci. Technol. XXXX, XXX, XXX−XXX distinguishing among green water (direct rainwater consumption by plants), blue water (ground and surface water), and gray water (a measure of water pollution expressed as the water requirements to dilute emissions). Footprint indicators are commonly used for assessments at the individual or company level; however for policy making purposes it is useful to construct footprint accounts for countries or regions instead. Such national footprint accounts can provide understanding of the relative importance and nature of a country’s impacts in a global perspective, and shed light on the underlying drivers of these impacts. Moreover, the footprint approach allows a quantification of impacts of domestic consumption on nature worldwide. Several attempts to construct national footprint accounts have been made: Global Footprint Network (GFN) regularly constructs national accounts of Ecological Footprints for most countries of the world, addressing both land use and CO2 emissions; 6 the Water Footprint Network has made similar accounts for water footprints; and Hertwich and Peters presented carbon footprint accounts, which were later updated by Peters et al. and are displayed online at ref 10. Consumption-based accounting adds considerably to analysis complexity compared to territorial accounts, because products may accumulate significant embodied impacts far upstream in complex international supply chains. Multiregional input− output (MRIO) analysis is able to account for complete supply chain effects by taking a top-down approach. While MRIO analysis has been systematically applied in carbon footprint calculations, the Ecological Footprint and the water footprint were developed as bottom-up approaches based on direct land and water use of key sectors. Still, there have been several studies that have used input−output (IO) techniques for measuring EF and WF. Lenzen and Murray and Wiedmann et al. demonstrated the advantages of using IO for EF accounting. McDonald and Patterson used MRIO to analyze regional interdependencies for New Zealand’s EF, while Feng et al. used a global MRIO model to calculate WF, following similar MRIO-based analyses for China. A material footprint, quantifying the cumulative amount of material natural resources (domestic extraction used all over the world) embodied in the consumption of the EU, has been estimated by ref 17 and denoted as raw material consumption, which belongs to a group of economy-wide material flow indicators. In this study we analyze environmental footprints of the EU27 countries, and how environmental pressures are displaced among them and to the rest of the world. We present comprehensive accounts of the three footprints, calculated using a common model frameworkbased on a global MRIO modelto account for supply chain effects (see the Supporting Information (SI) for detailed accounts). A drawback to input−output based EF and WF assessments has been loss of detail at the product level, because land and water use depend heavily on agricultural products, which are usually aggregated into a few bulk categories in input−output tables. The extended MRIO model used in this work partially overcomes the traditional disadvantages of low product detail within the MRIO system by including satellite accounts track the production and international trade of a range of specific primary crop and forestry products. By quantifying three different footprint indicators simultaneously and under a common methodological framework, we are able to assess pressures on three different compartments of the environment in a coherent manner, allowing a fuller picture of the true environmental pressures put on the planet by consumption activities in the EU. This should help to avoid environmental pressure shifting caused by focusing on a sole type of environmental problem. We include carbon footprints (CF), blue water footprints (WFb), and land footprints (LF) in our analysis. The LF is equivalent to the Ecological Footprint excluding carbon uptake land, since this is directly related to CO2 emissions already captured by the CF. We also chose to focus on the blue component of the water footprint, since gray water is not a measure of water consumption in the direct physical sense but of water pollution, and green water is direct rainwater consumption, which as argued by ref 20 is a pressure that would be double counted in combination with the LF; however the interested reader can find results for the complete EF and WF indicators, as well as a discussion of the various footprint indicators, in the SI. Note that according to the “Driver, Pressure, State, Impact, Response” (DPSIR) framework used by the European Environmental Agency, these are all pressure indicators. They present a single quantitative measure, which can be broken down in more detail, but they do not assess the resulting impacts. A key interest for this analysis has been the displacement of environmental pressure through trade. We speak of a displacement when the environmental pressure occurs in another country than the country of final consumption of the product whose production is the immediate cause of the environmental pressure, following the discussion of land use studies. In other words, if a pressure is displaced from country A to country B, emissions, land use, or water use occurring in country B serve the consumption in country A. Previous research on displacements of environmental pressures through international trade has indicated that Europe generally tends to have net imports of embodied pressures from other regions of the world. For the water footprint, the results of Hoekstra and Mekonnen indicate that a large share of the water footprint of European countries (especially in western Europe) tends to be external compared to developin