Canadian Shipper

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Is buying local truly the best way to reduce GHG emissions?


To quote Kermit the Frog, “It’s not easy eating green.” Much of the confusion stems from transportation’s role in the food chain’s total carbon footprint.

When sustainability issues started to grab headlines, environmental activists began targeting the impact of food miles or tonne-km (t-km) related to moving products from farms and production sources to retailers.

To cut greenhouse gas (GHG) emissions, they proposed reducing food miles by sourcing products closer to consumers. Truckers became easy targets. They move the vast majority of fresh fruits and vegetables under refrigeration.

A Toronto-based group, Local Food Plus (LFP), recently concluded that shifting even a small fraction of grocery offerings to local food can have a huge economic and environmental impact. York University professor and head of LFP’s standards development team, Rod MacRae, estimates that if 10,000 Toronto families shifted $10 of their weekly food purchases to local sources for a year it would be equal to taking 908 cars off the road for a year. He emphasizes refrigerated truck deliveries of fruits and vegetables from California and Florida. As well, that $5.2-million switch would benefit the local economy – not those in the US and elsewhere.

Says MacRae: “LFP’s objectives are to increase the use of Canadian food products – not just fresh, but also frozen and canned – that will optimize production and distribution systems. It will also reduce our dependence on imports while increasing the sustainability of the entire food flow system.”

In fact, the group has a wider social mandate. “We want to create a new category of food producers beyond organic and conventional,” says LFP vice-president, Don Mills. “We certify those who follow practices supporting sustainability, fair labour practices, animal welfare and bio-diversity.

“We also introduce our members to distributors as well as universities and hospitals seeking reliable sources of such products.”

However, some researchers now conclude that transportation is not the villain after calculating the greenhouse gas (GHG) emissions from the entire farm-to-fork cycle. The 2008 study, Food-Miles and the Relative Climate Impacts of Food Choices in the United States by Christopher L. Weber and H.C. Scott Mathews, states: “Transportation, as a whole, represents only 11% of life-cycle GHG emissions, and final delivery from producer to retail contributes only 4%.” (Based on 1997 US data, their calculations do not include consumer transportation to and from retail stores.)

Columbia University Earth Institute research scientist, Christoph Meinrenken supports those findings. He says: “With the exception of a few outliers, transportation accounts for 20% – tops – of the cradle-to-grave, food-cycle carbon footprint.”

His 2010 report calculated that each 1.89 litre jug of Tropicana orange juice created 1.7 kg in GHG emissions. Of that total, growing and production accounted for 60% (including 2% for inbound deliveries), distribution (including warehousing) 22%, packaging 15% and disposal 3%. At 35%, the biggest single culprit is natural-gas-rich fertilizer used in orange groves.
Meinrenken’s findings were summarized in a Time magazine article, Going Green: Sustainability Squeezed? A fertilizer initiative at Tropicana seeks to shrink agriculture’s (massive) carbon footprint.

While such research takes transportation off the hook, how can we increase food cycle sustainability? Weber and Matthews offer proposals based on solid logistics principles that include considering the varying impact of different products and various transport modes. For example, they concluded the top three contributors to freight requirements by food group are cereals/carbohydrates (14% of the total), red meat (13%) and fruits/vegetables (10%).

In regards to deliveries as a proportion of total transportation, requirements ranged from 9% for red meat to around 50% for fruits/vegetables. As well, the breakdown by transport mode indicates international water at 29%, truck at 28%, rail at 29% and inland water at 10% and air at 1%.

As well, they conclude that trucking is now responsible for 71% of total transport-related GHG emissions due to its large share of t-km and relatively high GHG intensity.

As a result, they suggest, “Shifting less than one day per week’s worth of calories from red meat and dairy products to chicken, fish, eggs, or a vegetable-based diet achieves more GHG reduction than buying all locally sourced food.”

Besides eliminating the food-miles discussion, their recommendation that more balanced and healthful eating habits diet consisting of foods conventionally sourced may also yield the added benefit of boosting food cycle sustainability.
Ultimately, food miles researchers and groups such as LFP can co-exist. “We encourage people to support local food sourcing groups,” says Matthews. “But not to reduce food’s carbon footprint. There are better ways of doing that.”


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