Yes, Consumption Really Does Drive Climate Impacts and Resource Use
Intuition has long suggested that consumption plays a key role in driving climate impacts and resource use. A recent article in Yale’s Journal of Industrial Ecology brings rigor and detail to this understanding. Using a new multiregional input-output database (EXIOBASE 2.2), which describes the world economy at the detail of 43 countries, five rest-of-the-world regions, and 200 product sectors, the authors are able to trace the origin of the products consumed by households and represent global supply chains for 2007. It shows that household consumption contributes to more than 60 percent of global GHG emissions and between 50 percent and 80 percent of total land, material, and water use.
Traditionally, the analysis of household environmental impacts has been based on national statistics and production systems, treating imported goods as if they had been produced in the country where they are consumed. The energy and emissions intensities of products produced in different countries can be quite different, however, reflecting a combination of differences in the structure and efficiency of economies and in the product mix being produced.
The article, “Environmental Impact Assessment of Household Consumption,” advances the understanding of the impact of consumption by distinguishing between direct impacts (e.g., CO2 emitted when driving a car), indirect impacts (CO2 emitted by a truck transporting products to a supermarket which are then purchased by consumers) and indirect foreign impacts (CO2 emitted when the products are manufactured in China and then sold in another country). This perspective is important: The research shows that 80% of the impacts that can be attributed to consumers are not direct impacts, but are the environmental effects from actually producing the goods and products that we buy.
Households in the United States alone contributed to a quarter of global emissions in 2007, or 5.6 gigatons of CO2-eq (the unit used by researchers to express the sum of the impacts of different greenhouse gases, such as carbon dioxide, methane, nitrous oxide and sulfur hexafluoride). The U.S. contributed 18.6 metric tons (t) CO2-eq per capita (CO2-eq/cap) whereas the world average is 3.4 t CO2-eq/cap. In terms of the total final demand, the U.S. GHG emissions were 4.9 times higher than the world average from a consumption perspective while the emissions were only 3.9 times higher from a production perspective. Thus, the U.S. is a net importer of GHGs embodied in traded goods, largely owing to household consumption — 74 percent of the country’s final demand. Mobility, shelter, and food are the most important consumption categories across the environmental footprints. Globally, food accounts for 48 percent and 70 percent of household impacts on land and water resources, respectively, with consumption of meat, dairy, and processed food rising fast with income.
The new rigor and detail enabled by the use of EXIOBASE 2.2 goes beyond presenting a snapshot of household emissions and resource use. It provides a different perspective on what shapes environmental and resource footprints. And, it is hoped, a foundation for strategies for environmentally-driven changes in household spending.
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