Are farmers markets or supermarkets the low carbon food choice?
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Are farmers markets or supermarkets the low carbon food choice?

Community and climate are both important considerations but they don’t always align.
February 9, 2024

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Urban farmers markets epitomize an environmentally-conscious lifestyle—home-grown vegetables, paper bags, the occasional beetle in your organic raspberries. Surely nothing could be better for the climate than buying food grown literally just around the corner? But conventional agriculture is now immensely efficient, and operates at a scale that makes pea-patch spuds look like very small potatoes. So we’re faced with a dilemma: Are farmers markets as good for the climate as they undoubtedly are for the community?

 

• • •

The Efficiency of Factory Farms

1.  The pea-patch price. There are many reasons to love your local community garden—a splash of color, pollinators, even health—but its hefty crop of carbon unfortunately may not be one of them, according to researchers from the University of Michigan. They looked at 73 urban agriculture sites in France, Germany, Poland, the UK and the US and found the community pea-patches had a carbon footprint about 10 times higher than conventional agriculture, per serving of food. Individual gardens and urban farms weren’t quite as bad, but overall urban agriculture generated six times as much carbon as traditional farms. One big contributor was community composting. While great at cutting waste, small-scale composting pumps out methane (a powerful greenhouse gas) if not managed well.

2.  Miles and packaging are minor carbon sources. It’s counter-intuitive, but buying a plastic bag of salad grown the next state over could be a lower-carbon choice than plucking a few leaves from your own garden. Packaging accounts for around just 5% of the carbon footprint of most foodstuffs, and distribution perhaps another 10%. Those emissions are dwarfed by the infrastructure needed to set up urban gardens, such as metal raised beds and garden sheds. Because small plots produce such a tiny quantity of food, it would take an average of 80 years’ of diligent back-yard gardening to “pay back” initial carbon costs, the Michigan researchers found. And most pea-patches will never get there.

3.  Go GMO for the planet? Big Ag is all about efficiency, which can sometimes (but not always) mean getting more output from less input. Some genetically modified crops enable low- and no-tillage agriculture that may (or may not) preserve megatons of carbon in farm soils. On top of that potential benefit, researchers at The Breakthrough Institute estimate that increased yields from GMO crops could cut European agricultural emissions by around 7.5 percent by avoiding additional CO2 emissions from land-use change.

 

• • •

Farmers Markets Still Have an Important Carbon Niche

1.  Pick the right plants. Don’t sow flower seeds over your veggies just yet. If you plant (or buy) local crops that are traditionally flown to supermarkets, you’ll claw back carbon savings. Tomatoes and asparagus are prime candidates for urban agriculture, according to the Michigan study, reaching carbon parity with traditional farms if grown locally or transported by ground. (And as every backyard gardener will insist, they’ll taste a lot better, too). Another way to slash emissions (by around 50%), is to upcycle raised beds, structures and other infrastructure from urban waste.

2.  The organic bonus. One thing almost all urban farms are doing right are avoiding using synthetic nitrogen fertilizers, a keystone of conventional agriculture. The NRDC says that eliminating synthetic fertilizers could lower direct global agricultural greenhouse gas emissions by about 20%, and that organic farms use 45% less energy compared to conventional farms, without sacrificing yield. There are multiple innovations on the way here, including cheap and efficient nitrogen-fixing bacteria.

3.  A carbon halo. Farmer’s markets offer more than just tasty, local food. This readable in-depth explainer from Vox touches on some of the halo effects of the community food movement, from lower rates of obesity and diabetes to benefiting the local economy, creating jobs, and reducing transportation emissions. Almost all come with caveats—the health benefits seem to accrue mostly to those higher incomes for example—but with local food accounting for a paltry 1.5 percent of US food sales, the farmer’s market movement still has plenty of room to grow.

  

• • •

What To Keep An Eye On

1.  Repurposing rooftops. Instead of focusing on the problems of growing food in an urban environment, Boston University researchers leaned in to one of the benefits. Buildings with a lot of people produce a lot of waste CO2 from human respiration. The BU team planted beds of spinach near HVAC ports on a campus building, and found that the plants grew four times as large on the exhalations of academic hot air. Similarly, corn grew at least twice as big.

2.  Commercial indoor farms. All the rage a few years ago, vertical farms indoors use artificial lighting and highly controlled conditions to produce quick-growing salad greens without the risk of pests, droughts or extreme heat events. But as the economy slowed, many are now shutting down, reports AP. Whether we ever get ambitious indoor wheat farms will depend on whether farmers can work out how to slash sky-high power bills, switch to renewable power, or return to some form of solar illumination.

3.  Greener supermarkets. Part of the charm of a farmers market is that it never really changes. Part of the carbon problem with grocery retail is that it has been changing too slowly. McKinsey notes that many supermarkets are now targeting net zero emissions, with electric vehicle supply chains, LED lighting and more efficient in-store refrigeration. As supermarkets consolidate into fewer, larger, and more powerful businesses “grocers have a unique opportunity to lead in this space for the good of both the planet and their businesses,” say the consultants. 

Change in CO₂ emissions and GDP, China
Top image: ©Anthropocene Magazine

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