- Mummy, there are ponies in my room. Real ones. They only come to life at night when I look at them.
- They sound like my principles. No wonder I can't sleep.
Local, seasonal & organic - or poppycock?
Like my child, I have a mishmash of views and fantasies that I only articulate when I'm looking straight at them. Many of these conflict. What's better for the environment, organic chicken or processed mock duck? Plastic-wrapped lentils imported from Peru or loose local vegies from the Co-Op? To help me decide, I'm using carbon dioxide and equivalent emissions (CO2e). This week, I took on three eco ideas at once and ran them head-to-head.
From farmer's markets to the 100-mile diet, locavores claim to cut emissions by cutting food miles. But the claims don't stack up. Most of the food's footprint comes from the farm. A sample of six studies shows that CO2e up to the farm gate accounted for 69% of canola oil, 80% of lamb and pork pate, 89% of wheat, 94% of olive oil and 96% of beef. That leaves less than 30% for everything else, including transport, packaging, sale, refrigeration and waste.
Focussing on food miles may starve the poor because it cuts trade from nations that have nothing else to export. It may also inadvertently increase emissions. This study cites two famous examples where New Zealand lamb and Spanish tomatoes shipped to the United Kingdom generated fewer emissions than the locally-grown UK equivalents.
Why is this? Food grown overseas uses long-distance shipping and road freight, both of which are highly efficient forms of transport. Transporting 20 kilograms of food from India to Sydney via cargo ship and then from Sydney to Canberra via truck generates 2.4 kilograms CO2e. You could buy a locally-grown version from a specialty shop or direct from the farm, but you'd probably need to drive further to get it. If that return trip took an extra 13.5 kilometres in a small car, it would generate 2.5 kilograms CO2e - more emissions than the total transport footprint to get it from India. The journey negates its purpose.
Why are we so worried about food miles? Before carbon footprinting and Life Cycle Analyses were common, we thought food miles were a major component of our footprint. After all, transport in developing countries is significant - but that's because we do it in cars. Our industrial food system also makes most food production invisible, so we tend to focus on the bits we can see, like transport and packaging. By all means, eat local if you want to, but don't imagine it cuts carbon.
Low-input grazing gives New Zealand lamb lower emissions than United Kingdom lamb,
even after you factor in the international shipping.
'Eat seasonal' is standard environmental advice. I couldn't find any studies to back it up. I couldn't even work out what a 'seasonal' diet meant. I live in Canberra. Should I eat food only grown in my region in the last week? Can I use Queensland and Tasmania to extend my range? What about food that's in season in Africa right now? Does my bread need seasonal flour? When do I get to eat pickles?
There's some logic to the idea. Food that's eaten soon after harvest may use less energy to store, refrigerate and process, although that won't cut carbon by much. More significantly, it might avoid emissions from heating a hothouse or greenhouse. But if 'eat seasonal' means shunning cold storage apples in favour of fresh cheese, it will increase carbon.
Conventional farming uses synthetic fertilisers, pesticides and concentrated feedstocks. All of these contain embedded emissions. Organic farming usually avoids or reduces these inputs. Organically farmed land also stores more carbon in the soil (up to 28% more or up to 450 kilograms more per hectare, according to two UN studies). This should give organic farming an edge. But industrial farming maximises yield, at least in the short term, and higher yield means lower emissions per kilogram of produce. Industrial farming may also lead to lower emissions for meat and egg production (but it sucks for animal welfare).
Does that mean organic food cuts carbon? It depends. I couldn't find any overarching rule. The closest I got was this Swedish study on smug field potatoes grown by 'climate rules' with low-impact fertiliser, which reduced their carbon footprint by 9%.
Who's laughing now, you smug Swedish spud?
How much CO2e did I save?
I don't get any carbon reduction for cutting food miles or eating seasonally. I'm taking a 9% reduction for substituting organic plant foods for conventional ones, where these were available in my local supermarket. While I could buy everything organic in a specialty shop, I'd have to drive further to get it and the journey would negate its purpose. I'm not taking a reduction for organic meat or dairy because, while I think these are better for animal welfare reasons, they don't cut carbon (and may actually increase it).
All up, this week's experiment saves me 17 kilograms CO2e across the entire year. It's not worth doing.
If not that, then what?
Local, seasonal and organic won't cut carbon. Three other heroes might, but they're hard to quantify.
Hothouse produce. Food grown in a fossil-fuel heated greenhouse is carbon intense, so much so that Kenya's response to the UK 'Food Miles' movement was a sensible 'grown under the sun' campaign. Unfortunately, most carbon literature comes from Europe where most hothouses are the energy-intense kind built to deal with harsh winters. Australian greenhouses vary. This study on Australian tomatoes shows the carbon footprint in one type of greenhouse is lower than for field-grown produce, and in another type of greenhouse is four times higher. The details matter, but you can't tell from the supermarket label.
Air freight. While food miles aren't that significant, air freight is an exception. If our 20 kilograms of food from India came by freight aircraft instead of a ship, its emissions would be almost fifty times higher. Again, this isn't labelled in the supermarket. I've written to all three major outlets and asked for details on air freight and hothouse production. I'll cover their response in my book next year.
Backyard Produce. I couldn't find any data on home-grown food. Logic tells me it avoids almost all of the carbon-intense inputs of industrial farming, so if you grow it, it's probably low carbon. But I can't say how much you save.
Good reasons to eat local, seasonal and organic
You might still want to eat local, seasonal and organic for other reasons, such as health, taste, political affinity, to keep local skills and economies alive or animal welfare. There are also environmental reasons besides CO2e. This kind of food might save water (then again, it might not - details matter). It will probably preserve topsoil, lead to better land management and save other natural resources. So go ahead and enjoy, but take a real carbon action as well by eating less meat and dairy.
Spreadsheet calculations, reference list and data discussion in the 'Notes' section, Week Sixteen.