challenge your assumptions

Here’s a great story on why the answers may not always be as obvious as you think. There’s quite a movement in the US and the UK (and presumably other countries) based on the assumption that we import so much food now that this can’t be good for the environment. Sounds intuitive, right? Shipping something like tulips to the UK from Africa seems very wasteful compared with growing them in Holland and a short ride across the sea to Britain.

However a recent study by researchers at Carnegie Mellon disputes this fact – their reasoning being that the transport costs are such a small part of the environmental cost of growing food, and in fact it may be more environmentally friendly to grow food in certain locations and ship it to where it’s needed. Here’s a paragraph from a summary:

The line, then, is that the prudent environmentalist will eat local in order to cut down on greenhouse gas emissions. Intuitively, that makes a lot of sense. Bananas shipped from Brazil can’t be good for the environment. But two Carnegie Mellon researchers recently broke down the carbon footprint of foods, and their findings were a bit surprising. 83 percent of emissions came from the growth and production of the food itself. Only 11 percent came from transportation, and even then, only 4 percent came from the transportation between grower and seller (which is the part that eating local helps cut). Additionally, food shipped from far off may be better for the environment than food shipped within the country — ocean travel is much more efficient than trucking.

A further example I heard recently was that buying apples grown in New Zealand can usually be a more environmentally choice than locally grown, because the conditions in New Zealand are so conducive to growing apples that they need very little extra help, such as fertilizers, irrigation etc, all of which are a greater environmental drain than the transportation.

The moral of this: always be ready to challenge your assumptions. The answers are often counter-intuitive or more complex than you would think.

2 Responses to “challenge your assumptions”

  1. Paul says:

    I totally agree, though it’s worth adding “always be ready to challenge the facts” :) Ocean shipping has recently been shown to be at least 50% more damaging to the environment than previously assumed (

    I do try to choose local, but for freshness, not for its environmental benefits. Though I live between two ports, so maybe shipped is the way to go :)

  2. Fiona says:

    What are you doing reading American Chemical Society journals? I’m a member of the society and I don’t even do that. :) This is a great article for one of the classes we are teaching next semester on environmental chemistry. Thanks for the heads up.

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