Does being a locavore add up?

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As I’ve argued before (here) there are a number of reasons why buying food locally is probably the least sustainable basis on which to base your food buying preferences.

First, transport is only a small component of the total carbon emissions from agriculture.

Second, most food can’t be grown locally without resorting to potentially environmentally damaging practices like excessive application of fertiliser, irrigation or artificial heating of greenhouses.

Third, even where the local area is suitable for growing certain foods, it might not be the most environmentally efficient location for a particular food.

Fourth, producers in more distant locations might have superior farming practices to local growers. Fifth, the environmental and economic cost of moving people is higher than the cost of transporting their food.

Now Stephen Budiansky has assembled an array of interesting factoids in this NY Times oped, Math lessons for locavores, to show the folly of being a locavore. He’s a stylish writer so you might want to read the full article; otherwise here are a few key quotes:

  • “Whether it’s grown in California or Maine, or whether it’s organic or conventional, about 5,000 calories of energy go into one pound of lettuce. Given how efficient trains and tractor-trailers are, shipping a head of lettuce across the country actually adds next to nothing to the total energy bill. Read the rest of this entry »

Is suburban sprawl a threat to farming?

One of the oldest processes in urban development is the conversion of peripheral land from farming to residential use. The standard argument is highest and best use: housing gives a bigger pay-off than farming. It’s the same basic logic underlying why natural bushland is cleared for agricultural use.

On Monday I looked at the idea of “food kilometres” but today I want to look at whether productive agricultural land should be converted to urban use.

Straight up, the evidence suggests urban development doesn’t pose much threat at all. The productivity of agriculture in Australia has increased 2.8% p.a. over the last 20 years, double the rate at which the wider market economy has grown.

Moreover, the Australian Natural Resources Atlas shows that the area of land used nationally for urban development amounts to just 0.5% of the area of land used for agriculture. Another estimate by the Australian Collaborative Land Use Mapping Program puts the ratio of urban land to agricultural land at 2.8%.

A more detailed study by Peter Houston published in 2005 found that agricultural land on Melbourne’s urban periphery comprised a little less than 6% of the total land base used for agriculture in Victoria. Melbourne seems to be an exception – the average figure for peri-urban areas across all mainland States is a mere 1%. Read the rest of this entry »

Is local food more sustainable?

One argument against suburban sprawl is that it sterilises agricultural land. A particular variation on this contention is that land should be preserved for agriculture so that carbon emissions in transporting food from farm gate to plate – “food kilometres” – can be minimised.

A frequently cited estimate is that food in the US travels on average 2,400 km from where it is produced to where it sold to consumers. We should therefore seek to grow as wide a range of food as possible as close to Melbourne as possible.

From Weber and Mathews, Food Miles and the Relative Climate Impacts of Food Choices in the US

All things being equal that makes sense. But of course it’s never that simple. Here are some pertinent issues to consider.

First, transport is not a major component of the total carbon emissions from agriculture. These researchers estimate that on-farm production accounts for 83% of the average US household’s carbon emissions from food whereas delivery from producer to retail outlets accounts for just 4%.

Second, most food can’t be grown locally without resorting to potentially environmentally damaging practices like excessive application of fertiliser, irrigation or artificial heating of greenhouses. This article cites a British study which found that because British tomatoes are grown in heated greenhouses, they emit 2.4 metric tons of carbon dioxide per ton grown whereas Spanish tomatoes emit 0.6 tons. Further:

Another study found that cold storage of British apples produced more carbon dioxide than shipping New Zealand apples by sea to London. In addition, U.K. dairy farmers use twice as much energy to produce a metric ton of milk solids than do New Zealand farmers. Read the rest of this entry »