Full disclosure: I wrote this to help promote my friend’s farm. But, I was really surprised that that difference in local vs imported is as big as it is! Part of this is because Nova Scotia is so far away from California, in other locations it might not be so clear cut. That’s all the more reason to grow more of our own food here.
Eating local has become a civic virtue, and with good reason. Local food gives one a sense of rootedness and belonging, results in fewer CO2 emissions, and tastes great. But how much better? A lot! Take lettuce, for example, which grows well both at St. Isidore Farm in Nova Scotia and also in California on the large farms that supply grocery store chains.
Eating local is one of those things you’re supposed to do, but how much of a difference does it really make? Is there a big difference in CO2 emissions and taste? I’m not really an epicurean, does it mater to me? I also don’t buy exclusively organic produce because a) I’m kind of poor b) I’m not completely on board with some of the permitted “organic” practices.
Local vegetable growing emits 4.3 – 8.6 times less CO2 than the Californian imports [5]. Locally grown has 1.4 – 2 times higher nutritional content [4], and lasts longer without spoiling, reducing waste [2]. In fact, the higher nutritional content means that local is also actually far cheaper, since to get the equivalent nutrients at the grocery store you’d have to buy (and eat) twice as much. Calorie wise it’s about the same, but most people aren’t eating lettuce for the calories.
When you buy local, the taste is better, they keep longer, and the nutritional content is higher! Another plus is that local vegetables can be heirloom varieties that taste better but don’t ship as well. Many vegetable varieties have been bred for transport durability as the primary concern to the detriment of their taste.
In contrast, from Californian harvest to Nova Scotia takes at least 3 days by truck, and generally 5-10 days with distribution centre layovers [2]. Not only does this affect the taste, but results in the loss of 30-50% of the nutritional content [4]. Have you ever wondered why things just don’t seem to keep in your refrigerator? They were already old when you put them in! 30% of food waste occurs in the home, but likely this is spoilage from long, harsh transportation, not consumer overbuying [2].
CO2 emissions associated with vegetables come from the farm production and transportation to grocery store. Californian farms are usually large scale and generate large emissions through irrigation pumping and mechanization. In fact, 6% of all energy used in California is used to pump water for crops, and that water use is often unsustainable [1]. Produce is usually transported by truck, 6000 km to Nova Scotia, with stopovers in refrigerated warehouses that also emit CO2 [2].
In contrast, St. Isidore Farm lettuce is hand harvested, with only a shallow well for irrigation. Ancient ground water aquifers are not depleted, and protection from the cold is a simple unheated greenhouse in the early season. Transportation is 30 km or less. Local vegetable production has at least 4.3 times lower emissions (with the exception of hothouses which have heating emissions higher than even Californian imports) [3]. All the more reason to continue with our solar greenhouse research that will allow for year round local produce without emissions.
[1] Agwaterstewards.org. 2020. Water & Energy – California Agricultural Water Stewardship Initiative. <https://agwaterstewards.org/practices/water_energy/> [Accessed 8 June 2020]
[2] MacRae, R.J. 2020. Challenges of food transport in Canada. Food Policy for Canada: joined up food policy to create a just, health promoting and sustainable food system. http://foodpolicyforcanada.info.yorku.ca [Accessed 8 June 2020]
[3]Plawecki, R., Pirog, R., Montri, A. and Hamm, M., 2013. Comparative carbon footprint assessment of winter lettuce production in two climatic zones for Midwestern market. Renewable Agriculture and Food Systems, 29(4), pp.310-318.
[4] Klein B., 1987. Nutritional Consequences of Minimal Processing of Fruits and Vegetables. Journal of Food Quality, 10(3), pp.179-193
[5] Study [3] was comparing California produce to local produce in Michigan. For Nova Scotia, emissions could be twice as high since it is twice as far to ship.
Sun Aquasystems 