Saturday, February 23, 2008

Food and the environment

For some reason I'm on's list of green living blogs, so I feel the obliged to say something about the impact of our food choices on the environment. Food is an incredibly charged topic nowadays with the organic and local food movements, the obesity epidemic, and rising energy prices, and for me the most important thing is that we understand all of the facts first. How much energy does it take to produce meat versus grain? How much does a healthy diet contribute to lower risk of disease? Does local food really take less energy to produce than global food?

Unfortunately, I fear that the political expediency of food issues often muddles the facts and inundates the public instead with biased rhetoric and misleading insinuation (and sometimes just plain false claims). It's easy to demonize things like fast food and factory farming, but I think it's more important for people to make informed choices. It's not evil to still choose to eat hamburgers imported from thousands of miles away, but no one should make that choice without knowing what the facts are.

So here are some of the stylized facts as I understand them.
  • Animal-based foods unambiguously use more energy and causes more pollution than plant-based foods. According to a UN report,

    The livestock sector emerges as one of the top two or three most significant contributors to the most serious environmental problems, at every scale from local to global .. The impact is so significant that it needs to be addressed with urgency. Major reductions in impact could be achieved at reasonable cost.
    The report shows that livestock accounts for 18 percent of global greenhouse gas (GHG) emissions and 8 percent of global water use. From a recent report in the New York Times, a 6oz beef steak generates 64 times the GHG as a meal of rice and vegetables. Pork and chicken are more energy-efficient sources of animal protein, and an article in Salon references a study which shows that a chicken-rich diet may even be more energy-efficient than a vegetarian diet which includes milk and dairy.

    Of course, a vegan diet is the most energy-efficient of all. And toward this goal, one of my favorite hobbies lately has been veganizing my favorite dessert recipes (you can see some of the results on this site). It's been a lot of fun and I've been amazed at how delicious the results are!

  • Local food can be more energy-efficient, but this is not always the case. In other words, distance between where food is produced and consumed is NOT a good measure of how much energy is used from farm to table.

    An article in the Boston Globe details the complicated factors which must be taken into account when comparing local and non-local food. Mass- versus small-scale transit and the energy economies of agriculture in different climates makes up much of the difference. Tomatoes in Sweden, and apples and lettuce in Great Britain, for example, make more sense to ship from foreign producers than to produce domestically. However, shifting to ward local production in states like Iowa and California may make a lot of sense.

    What is clearer is that local food is likely to be fresher and retain more flavor and nutrients than food shipped from far away. Thus, it is reasonable to prefer local on the basis of quality, but the environmental argument is not always sound.

    Despite all of the complexity, all is not lost in the local food debate. Although I haven't seen studies addressing this specific issue, it also seems quite clear to me that a good way to cut the energy-intensity of our food is to shift consumption to things which are in season and native to our local environments so that the economies of local food work in our favor. Consuming highly-perishable produce which is out of season (e.g. asparagus in the winter) almost surely uses more energy than sticking to kale in the winter and asparagus in the spring.
  • Efficient Cooking

    Cooking is far from the most energy-intensive household activity, and if you do one thing to reduce your home energy usage, it should probably be installing more and better insulation. With that said, different cooking methods do use different amounts of energy, and here is a rundown of some tips on saving energy while cooking (in no particular order, since it's hard to quantify how important each one would be to overall energy use)
    • Microwave cooking is almost always the most efficient cooking method (see this comparison for baking), so if possible use the microwave. Estimates vary, but generally microwave cooking can save about 50% of the energy compared to conventional stovetops. However, consider putting your microwave on a power strip so you can turn it off when not in use. Appliances like microwaves draw standby power when they're just lighting up the digital clock, and this can add up over the course of a year to be more than the total energy used in actual cooking.
    • Use an electric kettle to boil water whenever possible.
      I have one from T-Fal that I use several times every day and it is faster and easier than boiling on a pot on the stove. Electric kettles are more efficient because they heat the water directly without heating the surrounding air or vessel, and they automatically shut off when the water has reached boiling.
    • Cook with the lids on pots and pans whenever possible, especially when cooking watery dishes to prevent steam from escaping.
    • Plan ahead
      • Obviously, cool food to room temperature after cooking before putting in the fridge or freezer.
      • Thaw frozen items in the refrigerator overnight instead of on the counter or in the microwave. For meats, this leads to the best results and greater food safety too.
      • Soak grains, beans, and even pasta overnight before cooking. Most of the cooking time for these foods actually comes from the time it takes for water to penetrate to the center, not the temperature needed to cook them. Presoaking also reduces the amount flatulence-inducing agents if you pour out the soaking water.
Books and references on food safety, nutrition, and the environment:
  • Livestock's Long Shadow (UN report)
    The definitive report (to my knowledge) on the environmental impacts of the livestock industry.

  • Fast Food Nation (and other work by Eric Schlossler)

    I like Schlossler's pioneering work (which paved the way for Omnivore's Dilemma and the bevy of other journalistic tomes) in the grand muckraking tradition. He takes an even-handed view of the fast food industry from top to bottom, and doesn't neglect the human costs to laborers as well as consumers.

  • Food Politics, Safe Food, What to Eat
    Marion Nestle is a professor of nutrition and presents thoroughly-researched, fact-based accounts of the politics, nutrition, and safety of the American food industry. In her latest book, What to Eat, she condenses her collected wisdom into practical advice for consumers.

  • The Omnivore's Dilemma (although I would skip the last chapter)

    Michael Pollan is perhaps the premier food journalist of our day, and The Omnivore's Dilemma really marked a turning point in public sentiment when local and organic food truly broke into the mainstream. His book is wonderfully written and his documentation of different farming methods is eye-opening, but I find his strong personal views to color the narrative too strongly. In particular, especially toward the later part of the book he glorifies local food and the act of personally hunting and foraging one's meals from start to finish without addressing the costs this type of lifestyle would entail.

  • Rethinking the Meat Guzzler (recent NY Times report)

    Gives some nice facts and figures and good arguments for reducing the amount of meat in our diets.
  • The Locavore's Dilemma (Boston Globe)

    This article delves into the tricky math behind question of whether local or global food is actually better for the environment. While local food has fewer miles to travel, the report shows that mass-scale long-distance travel actually only uses a tiny fraction of the energy used in small-scale local transport (such as using cars to go to the farmer's market or small trucks to transport food from farms). Moreover, there may be environmental rationales for growing food in climates optimally suited for them instead of closer to consumers.
  • Earth to PETA
    A article goes through some of the politics and scientific findings about meat and greenhouse gas emissions and presents the surprising finding that chicken may be one of the most efficient sources of protein.
  • MichaelBluejay, a site with lots of energy-saving tips and figures
  • Some great tips on energy-efficient cooking by one of my favorite food writers (and fellow Caltech alum!), Harold McGee


Raymond Chee said...

Nice topic you got there~ Raymond from Malaysia

Anonymous said...

great, thank you !!!!! but what about negative health costs of microwaving?