Tracing it Back, and Farther Back Still

By Adam Brock

Reading Joel Makower’s most recent article on Cooler, a carbon-neutral online retail portal, I came across UC Berkeley’s Lifecycle Climate Footprint Calculator – one of the best tools I’ve seen yet for quantifying environmental impact. What sets the Berkeley tool apart is that it attempts to put a number on the emissions that are more than one step removed from our consumer choices. From the methodology report (PDF):

The model assumes that consumers are ultimately responsible for not only end‐use impacts, such as air emissions from the burning of fossil fuels in automobiles, but also the indirect environmental impacts resulting from the production of goods and services throughout the commodity and service chains.

The Berkeley researchers are tackling head-on the question at the heart of any environmental impact assessment: how far back do you go? If you’re footprinting, say, a banana, do you include the emissions from producing the fertilizer used to grow it? What about the emissions from the mining operations used to extract the phosphorous for the fertilizer? Ideally, it should all be factored in – but practically, it’s another story. Trying to collect and crunch all that data is a pretty insurmountable process.

So how did Berkeley do it? By piggybacking on another clever tool, Carnegie Mellon’s Economic Input-Output Life Cycle Assessment (EIO-LCA). Rather than trace back the impact from every individual product and process, EIO-LCA assumes that emissions between sectors of the economy match up with economic activity between those sectors, data that’s readily available. Drawing from a matrix provided by the Department of Commerce, the model will show, for instance, that a million dollars of economic activity in aluminum production also generates $258,000 in alumina refining and $168,000 in power generation and supply – numbers that can then be used to estimate emissions from those secondary activities.

Neither Berkeley’s tool nor the Carnegie Mellon database it draws from can be considered entirely accurate; it’s an admittedly shaky assumption, for one, that carbon emissions are directly tied to dollars. Still, these tools at least try to capture what nothing else, at this point, can: the ways in which our consumer choices reverberate back through the economy. It’s an important consideration – and one that the fledgling science of ecofootprinting has yet to account for.


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