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Food Footprint: Cal experts calculate your diet’s carbon cost

September 17, 2013

What’s the carbon footprint of a chicken leg? How many tons of CO2 were emitted during the making of your salsa? Have you considered the environmental consequences of your clove of garlic?

After spending the past year-and-a-half pondering exactly those kinds of questions, an international team of engineers with one foot in Berkeley has come up with a new method of measuring the climate-warming impact of individual food products. That isn’t just for the benefit of eco-conscientious shoppers wracked with uncertainty over which non-dairy milk is the greener option. If approved by the state’s Air Resources Board—which hired researchers from Berkeley, Northwestern, and the European consulting firm Ecofys to come up with this new methodology—this could prove useful to the state bureaucrats charged with overseeing California’s cap-and-trade policy.

Under this system, codified within the “Global Warming Solutions Act” of 2006, the total tonnage of global-warming gases emitted by high-emitting industries is capped—a cap which is lowered from one year to the next. The right to pollute beneath that legal limit is bought and sold in the form of “allowances”.

To make that transition towards carbon-constricted capitalism a little easier for California industry, in these first few years of California’s cap-and-trade’s implementation, most of the carbon allowances are handed out for free to polluting businesses based on how much each one has emitted in the past. The message for those covered companies: Allow your emissions to creep up and pay for the privilege. Likewise, proactively green businesses will be rewarded with the extra allowances they don’t use, which they can sell to their dirtier competitors.

That presents a big question for regulators: How many allowances does each business get? Stepping back, how does the state even go about deciding this? This was the question put to Eric Masanet (who recently left Lawrence Berkeley National Lab for Northwestern), Margot Hutchins at Berkeley, and Paul Blinde at Ecofys.

Europe, the largest jurisdiction to implement a climate-minded emissions market, only offers limited guidance, according to Hutchins, associate director at Berkeley’s Laboratory for Manufacturing and Sustainability. Whereas in the E.U. greenhouse gases disproportionately come from large-scale, homogenous industrial processes—the making of cement, the manufacture of glass making, and the extraction and refining of oil and gas—the California economy is based much more on food and agriculture.

And tracing the greenhouse-gas-emitting legacy of a barrel of oil on one hand, and a can of beer on the other, are entirely different processes.Calculations are particularly complicated in cases of food production that takes only one input but produces multiple foodstuffs. or so-called “branching facilities, says Hutchins.

“In a dairy facility that makes both milk and cheese, you are using different amounts of energy to get two different products,” says Hutchins. In other words, when it comes to greenhouse gas emissions, there is no such thing as a “typical” dairy farm. Emissions will vary dramatically from one facility to the next based not only on the scale of production, but on the particular mix of dairy-derivatives it produces. Climactically speaking, not all lactose is created equal.

“Part of our methodology development was just trying to figure out where to draw the line,” says Hutchins. “Is it important, for instance, to differentiate skim milk from whole milk? What about different types of tomato paste?”

Pasta sauce aficionados take note: it turns out that the more concentrated the paste, the more energy required to produce it.  

Hutchins and her research team, which included Dr. David Lettieri, Dr. Vince Romanin, and PhD candidate Maribel Jaquez, received varying degrees of cooperation from major manufacturers in the sugar, beer, poultry, and dried seasoning industriesas they sought to peek inside facilities and suss out their respective production processes. Meanwhile, Northwestern’s Masanet focused on tomato canning, dairy, snack food and wine. Ecofys concentrated on petroleum and glass.

And from product to product, even within the same industry, those emissions varied wildly.

“Some of the sites we visited have been in use for 50 years,” notes Hutchins. “Comparing them to facilities from the past five years, you get a sense of the strides we’ve made in terms of energy efficiency, which is really encouraging. But it also raises a bigger question of what to do with those old 50-year-old facilities, which might play a very big role in their communities.”

After posting the methodology on its website for public review earlier this month, the state’s Air Resources Board will hold a hearing on whether to adopt the system on Oct. 24th. If it does, it will mark the first time that product-by-product emissions benchmarks are recognized by law.

For those who tract the minutiae of environmental policy, this is no small matter. In a report by Daniel Kammen and Christopher Jones, professors at Berkeley’s Energy and Resources Group, the consumption of food can make up between 10 and 30 percent of the carbon footprint of a typical American household.

“For Californians who eat meat, it is often 20 percent of their overall carbon diet,” Kammen tells us. “The food footprint is a big deal.”

By bringing food under the umbrella of an emissions reducing cap-and-trade system—something the Europeans chose not to do—and making sure that its emissions are accurately accounted, California would be tackling what has been an untouched source of overall greenhouse gas emissions.

“California really is an interesting state in the way that it has set a precedent in so many areas,” says Hutchins. “This is the first time anyone has taken a crack at emissions benchmarks for food, and I do expect that it will be considered elsewhere.”

—Ben Christopher

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