Circle of Responsibility

Low Carbon Diet

In the United States, mitigating climate change has largely been debated as a matter of reducing the amount of carbon dioxide emissions generated as a result of burning fossil fuels to power vehicles, buildings, and other energy users. While these concerns are critically important, a refined view of the problem shows that changing the global food system is also imperative.

The global food system contributes approximately one-third of anthropogenic greenhouse gases. No other broadly-defined ‘sector’ – including transportation or mining – is responsible for such a large share. And the world’s changing climate is having a marked effect on the food system as well, altering farmers’ and fishermen’s abilities to harvest food to feed an ever-growing world population.

In November 2005, the Board of the Bon Appétit Management Company Foundation voted to pursue a program based on emerging science that outlined how the food system contributes to global warming. After months of research, the Bon Appétit Management Company announced the Low Carbon Diet Program in April 2007, the first national program to highlight the significant connections between food and climate change and take steps to reduce the food service sector’s contribution to the problem.

Background

Much of the developed world’s food system relies heavily on fossil fuels to grow, transport and process food. Burning fossil fuels cause carbon dioxide (CO₂) emissions but, as a percentage of the world’s and nation’s CO₂ emissions, the food system’s share is relatively modest. A much more significant problem is the amount of more powerful greenhouse gases generated by livestock production, agricultural practices, excess water usage, and refrigeration gases. Equally concerning is the amount of deforestation and soil erosion  that occurs when land is cleared for food production or too many chemical inputs destroy soil fertility. While the food system’s CO₂ emissions are modest, methane, nitrous oxide and CFC releases are enormous. 

What the Science Says

In the United States, where an inventory of emissions was not required (as it was for countries that signed the Kyoto Protocols), there hasn’t been robust literature to read (or community of scientists to debate) the global warming potential of the food system. This is changing. Lifecycle assessments (LCAs) – studies that examine a range of environmental impacts of a given product from the start of a production process to its eventual disposal – were originally designed to quantify manufacturing impacts but the methodology has now been adapted for food products. The process is exhaustive and highly quantitative. As a result, they are expensive to conduct so LCAs have typically been undertaken only for very high-impact or high-volume food products. With hundreds of studies now complete in Europe, North America, Asia and Australia, some big patterns are emerging about the food system that are irrefutable:

1. Meat and cheese from ruminant animals is a “high-carbon” food no matter how you slice it. The science on this matter is clear, despite the intrepid bloggers who genuinely want to believe otherwise. An exhaustive report by the United Nations' Food and Agriculture Organization (FAO) showed in 2006 that “overall, livestock activities contribute an estimated 18 percent to total anthropogenic greenhouse gas emissions (GHGe).” The reasons are primarily due to three factors: large quantities of methane gas released by ruminant animals through their digestive systems (burping) over their lifetime; waste management, which is responsible for methane and nitrous oxide releases; and deforestation for grazing pastures. The impacts from growing grain to feed animals are also environmentally significant, but the humanitarian element – of growing grain for animals rather than for direct human consumption in a world where there isn’t enough food for people – is perhaps cause for greater concern. Grain production also requires enormous water resources, which competes with human needs for water in many places around the globe.

With well-documented evidence that the livestock sector is responsible for 18% of the world’s GHG emissions, and the food system is responsible for approximately 33%, the math is easy: meat and other products (such as cheese) from ruminant animals such as cows, sheep and goats, are the cause of half of the food system’s overall contribution to climate change. Whether it comes from near or far, meat and cheese are “high-carbon foods.”

2. Food waste (and over-consumption) generate emissions throughout the supply chain. Millions of tons of food are produced and wasted every day. One survey, based on Federal statistics, estimated that commercial retail food establishments (full service restaurants, fast food, supermarket and convenience stores) throw out 54 billion pounds of food each year. Every American household, on average, discards more than 1.25 pounds of food as waste each day (about 14% of total food purchases, measured by dollars), not including what is tossed into compost piles or sent down the disposals. These figures add up to enormous sums but don’t even include on-farm food losses. The figures may also be understated. In 2009, a UN report found that over half of the food produced globally (and in the U.S.) is lost, wasted or discarded as a result of inefficiency in the human-managed food chain, including as much as one-quarter of all fresh fruits and vegetables. From a climate change perspective, food losses carry two burdens: emissions generated by the production, distribution and preparation of “unnecessary” food; and the generation of methane gas at landfills by organic matter that decomposes there.

British household and commercial food losses have been found to be similar in scope, prompting Waste and Resources Action Programme, an organization in the U.K., to note that carbon savings could be equivalent to taking an estimated 1 in 5 cars off the road if we avoided throwing away all the food that we could have eaten.”  WRAP further pointed out that the “focus on the health advantages of fruit and vegetable consumption is encouraging us all to buy an increasing amount of fresh produce, a significant proportion of which is wasted.” They found an interesting dichotomy: people are “concerned about throwing away plastic and other waste perceived of as non-biodegradable but less so about biodegradable waste which is not generally regarded as an environmental problem.” Their survey revealed that “40% of people thought that food thrown away is not an issue because it is ‘natural and biodegradable’ and that nearly three-quarters of people thought that packaging was more of a problem than food waste.” From a climate change perspective, the opposite is true.

Landfills are a significant contributor of methane emissions, a greenhouse gas 23 times more potent than carbon dioxide in trapping heat close to the earth’s surface. The big contributor to methane formation in landfills is organic matter – including, very significantly, food scraps.

3. Air-freighting adds a hidden environmental cost with many popular seafood species.

Super-efficient sonar technologies, giant trawlers, and simply too many boats on the water have been responsible for overfishing many large species and destroying ocean habitats, like coral reefs, that are ‘home’ to many others. In addition to causing long-term and potentially irreversible environmental damage, many fishing vessels use enormous amounts of energy (and generate greenhouse gas emissions) to catch fish, and many farmed species are grown in systems that use lots of energy. Scientific research is emerging that shows, however, that the greatest greenhouse gas burden for many species is the mode by which they are transported to supermarkets or restaurants. Many types of fish sold as “fresh” is almost certainly flown by air in gel-ice packaging (or in water, such as live lobster). By far the most environmentally benign species are those that are caught or grown within a short distance of being produced, but currently less than 30% of all seafood consumed in the U.S. comes from U.S. waters. For species caught from afar, “frozen at sea” (or individually quick frozen for farmed seafood) products are typically shipped by boat rather than flown by air. The difference is a ten-fold increase in emissions for air-freighting.

Lifecycle researchers are also confirming that smaller (low-trophic) species, such as herring, clams, sardines and mussels, are generally low-carbon foods due to the fishing or farming methods that do not use many fossil fuel inputs, including what they are fed. If flown a great distance as a “fresh” product, however, the benefits are largely cancelled.

4. While fruits and vegetables are “lower carbon” options than highly processed foods or proteins, environmental benefits are cancelled if they are air-freighted or hothouse-grown.

Ounce for ounce, fruits and vegetables as a whole category contribute fewer emissions than animal proteins, but air-freighting produce is very emissions-intensive. Air-freighting is typically reserved for highly perishable produce that command higher prices, such as fresh berries and asparagus in winter, and pineapples year-round. Tomatoes aren’t flown, but to avoid the common practice of picking tomatoes when they are green and “ripening them” with ethylene gas – a process that seems to ensure mushy flavor and a pinkish color – producers have taken to growing “winter tomatoes” in hothouses. The result is better flavor, redder color, and far greater emissions than seasonal crops grown in dirt. This is even true for tomatoes grown in “local” hothouses. The burning of fossil fuels to power the hothouses causes emissions (much more than the transportation of the product after they are produced).

5. High energy usage (and carbon emissions) can be caused by old or worn heating and refrigeration equipment in commercial kitchens and by inconsistent application of operational standards.  

In the U.S., the assumption has been that commercial (and residential) equipment that uses energy to run emit greenhouse gases principally through burning fossil fuels to power them. This is a serious source of emissions to be sure, but recent evidence suggests that refrigerant losses varies widely and can be as high as 50% of the corresponding figure for electricity usage. Refrigerants include CFCs, a potent greenhouse gas. European supermarkets, who have been measuring GHG emissions for many more years than their US counterparts, are reporting that refrigerants account for 25% of some stores direct emissions inventory (that is, stores, distribution centers, transportation fleets, but not food production). Third-party independent data of several Bon Appétit-run kitchens confirmed how energy usage contribute additional burdens because minor equipment malfunctions or broken parts can cause energy losses of 30% or more. 

6. Improper disposal of “eco-friendly” packaging may actually do more harm than good.

“Grab and go” packaging has long been an environmental irritant, and Americans still discard many items made from virgin and non-renewable products (such as plastic water bottles) where there is reasonably consistent demand for the product. Whereas many municipalities have developed robust recycling programs over 30 years, municipal composting lags far behind. Independent LCA research comparing different types of packaging materials is very limited (most studies are paid for by corporate sponsors who could benefit from results reported in specific ways), but marketing claims abound. What we do know is that all types of to-go containers (hot and cold drink cups, salad and entrée containers) are produced with the benefit of fossil fuels at some stages of their lifecycles. Even the so-called renewable products (such as those made from corn), are made possible with nitrogen fertilizer application in corn fields, and to power long-distance transportation from field to manufacturing facility to warehouse to usage. LCAs thus far available show that there is little difference between products made from bio-based materials versus those made from lighter weight “non-renewable” resins. The irony is, of course, that there is a better developed market to capture and reuse the “non-renewable” resins than there is for the bio-based products. So-called ‘natural’ products, in fact, partially break down in landfills and cause methane emissions whereas the so-called petroleum-based products do not. Bio-based products, furthermore, potentially interfere with recycling processes, according to a paper from Environmental Defense Fund in 2008, because users think they should dispose of them in plastic recycling bins. (They shouldn’t.) Choosing the most greenhouse gas-benign to-go container, however, won’t have nearly the impact, however, as choosing foods that are comparatively lower-carbon foods.

Conclusion

Food choices we make every day can significantly impact climate change.  Researchers estimate that the average American diet produces more than 15 pounds of CO₂ per day which equals 5,600 pounds of CO₂ emissions per person per year. Compare that number to other “practical changes” suggested by respected environmental organizations that ask individuals to cut their carbon by taking shorter hot showers or changing light bulbs. A 10-minute shower is often cited as contributing four pounds of carbon per day (or 1,460 pounds of CO₂ per year); this is only about one-third the impact of our daily food choices!  

Bon Appétit Management Company developed operational initiatives to minimize our carbon impact in addition to increasing our guests’ awareness about the issues. We are concerned about the world’s changing climate and we are actively working to minimize our contribution. Click here for a list of Bon Appétit’s specific Low Carbon Diet commitments.

Sources:

Steinfeld H, et al. Livestock’s Long Shadow. United Nations Food and Agriculture Organization, 2006. Accessed June 2007.

Waste Resources and Action Programme, Understanding Food Waste, Oxford, United Kingdom, 2007.

Carlsson-Kanyama, A, et al. Food and life cycle energy inputs: consequences of diet and ways to increase efficiency. Ecological Economics 44:293-307; 2003.

Tyedmers P, Watson R, Pauly D. Fueling Global Fishing Fleets. AMBIO: A Journal of the Human Environment 34(8):635-638; 2005.

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