The Trouble with Carbon

The local food movement isn't nearly as green as you might wish

In Europe and the United States, the "locavore" movement is gaining
momentum, with a rising number of people refusing to eat anything that
isn't grown within 100 miles of home. The idea is that locally-based
food production will reduce the so-called carbon footprint and help to
mitigate global warming.

But will it? That 747 air freighter
packed with produce will spew roughly one metric ton of carbon dioxide
into the air for every 2,000 miles travelled, but the can of beans you
get from Africa is likely to have a smaller carbon footprint than the
drive you make to the supermarket to buy it.

In particular, a
New York writer named Colin Beavan has stirred international attention
with his just released book, "No Impact Man: The Adventures of a Guilty
Liberal Who Attempts to Save the Planet, and the Discoveries He Makes
About Himself and Our Way of Life in the Process" (available through
Amazon, US$16. 41). Beavan and his family tried to live in New York
while seeking to reduce consumption to a bare minimum, including using
no toilet paper and, among other things, not eating anything produced
more than 250 miles from the city.

The book has been widely
praised. "We as individuals can take action to address important social
problems. One person can make a difference," wrote Marion Nestle,
author of What to Eat. Similar gushing abounds.

But carbon
warming as a component of food production is complicated. According to
a study by Christopher Weber and H. Scott Matthews of Carnegie Mellon
University in the United States, transportation from the farm to the
supermarket accounts for just 4 percent of emissions related to food,
and a minuscule amount of the total carbon footprint. Although the
desire to buy local may be laudable, it may have little effect on
carbon output.

That organic farmer that the carbon-conscious
urban customer would like to buy from is likely to haul his produce
from his farm to the city in at least a pickup truck or something
bigger. The average SUV emits roughly 1.5 pounds of carbon per mile
travelled. The production of local food in cold climates, which may
require fertilizer, fuel and heated greenhouses, is likely to create
far more emissions than growing it in the tropics, where water and
sunlight are plentiful.

One study by Cranfield University in
England, for instance, shows that the carbon cost of growing flowers in
Kenya and flying them to the UK is perhaps a fifth of those grown in
the Netherlands.

Flowers are not food, of course. But one
study cited by the Guardian in 2008 involved Kenyan green beans. Kenyan
farmers do not use tractors. They use cattle manure as fertilizer,
their irrigation systems are simply ditches flooding fields instead of
fossil fuel-driven sprinklers, and water and sunlight are plentiful.

Home-grown
British beans are grown in fields sown with fossil-based fertilisers.
They are ploughed by diesel-burning tractors. And, as the Guardian
points out, produce grown in the developing world provides employment
to legions of the poor.

Gareth Thomas, England's Minister for
Trade and Development, at a seminar on air freight in 2007, pointed out
that driving 10 kilometers to shop in the UK emits more carbon than
flying the pack of beans from Kenya.

The Burlington &
Northern Railway in the United States, in an advertisement, says it can
move one imperial ton of freight 680 kilometers on a single gallon of
fuel. The organic farmer in the San Francisco Bay area may be doing
everything right, but moving his cabbages to a farmer's market in his
pickup truck every Saturday will produce far more carbon per unit of
produce than either the airfreight 747 from Kenya or the Burlington
& Northern train.

The Guardian study cites apples, which are
harvested in England in September and October. Some are sold fresh but
others are chilled and stored for as long as 10 months. The energy used
to chill them overtakes the carbon cost of shipping them all the way
from New Zealand. In the winter, the study points out, UK lettuce is
grown in greenhouses or polyethylene tunnels that require heating. In
winter, field-grown lettuce from, say, Spain produces far less carbon
even if shipped to the UK.

Are you cooking with gas or
electricity? Electricity is likely to put far less carbon in the air
because it is produced by a plant that may have carbon scrubbers.
Natural gas gives off carbon in individual kitchens.

Hong
Kong, self-contained and isolated from China, is an excellent test
case. The territory, with a population of 7.04 million, has
characteristics that seemingly should make it one of the least
carbon-friendly cities in the world. As much as HK$8,000 in food is
imported each year per person including 7.5 million tons of tomatoes
alone, for instance, or 7 million kilograms of salmon from Norway. But
at 5.5 tons of carbon emissions per capita annually, Hong Kong ranks
well behind Singapore, for instance, at 12.3 tons per person, a similar
city in terms of function and lack of hinterland.

If Hong Kong
were a country it would rank 65th in terms of total carbon emissions,
producing 37.411 million tons annually according to the UNDP, less than
0.1 percent of the global total – although that figure itself is in
question. According to a report to the Hong Kong Legislative Council
Panel on Environmental affairs on GHGs in June 2007, "The volume of GHG
emissions totalled about 44.8 million tons of CO2-equivalent (CO2-e)2
in 2005, accounting for about 0.2 percent of global GHG emissions.

Emissions
per capita in Hong Kong, which were around 6.4 to 6.5 tons in recent
years, are far lower than those recorded in most of the developed
economies such as the United States, (about 24 tons), Canada (about 24
tons), Australia (about 27 tons), UK (about 11 tons), Japan (about 11
tons), European Union (about 9 tons) and Singapore (about 9 tons). Hong
Kong's carbon intensity, as measured in terms of GHG emissions per unit
of gross domestic product, was 27.6 kg per HK$1,000 of GDP in 2005 and
was one of the lowest amongst developed economies," the panel found.

But
does it? Hong Kong is at the epicentre of some 60,000 companies owned
by the territory's residents, kicking up enormous amounts of
greenhouses gases in the Pearl River Delta. It all depends on who's
measuring what – including the GHGs produced on an organically correct
farm in, say, Northern California.

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