Sunday, January 31, 2010

User-defined content.

Several readers commented on my produce post (thanks!), so I thought I would compose a comprehensive response. Here are some of the questions brought up directly or indirectly by the comments:

“…how much of our carbon footprint comes from trucking food around? I suspect it pales in comparison to energy used in heating and cooling. While it's great to help when we can, are we sure we're investing our time where it has the most impact?”

First off, I want to say that I had several reasons for wanting to eat more ethically, especially when it came to eating meat and eggs. The beef industry, enabled mostly by cheap corn, is an unsustainable (economically as well as environmentally) and cruel system. The incentives to grow corn are based on the sheer volume of corn a grower can produce, which leads to ridiculous over-use of chemical fertilizers that eventually contaminate nearby water sources. The corn is then fed to cows in huge feedlots (CAFOs). Cows were not designed to eat corn, so they have to be pumped full of antibiotics in order to keep them from dying. They sit and lie in their own refuse, too confined to engage in natural behaviors. The “emissions” from these feedlots are tremendous, and the waste inevitably ends up contaminating the soil and groundwater. Finally, both the cheap corn and cheap beef, which has been shown to be unhealthier for human consumption than grass-fed, pasture-raised beef, is offered up to us in myriad forms, pretty much all of them unhealthy, contributing to the rise in diabetes, obesity, and heart disease in our country. There are many other problems too such as contamination of industrial meat and the overuse of antibiotics leading to more resistant strains of nasty bugs. I’m not even going to discuss the chicken/egg industry here and now, but it’s awful too. For a more complete and referenced accounting of these issues, read this article or watch King Corn as a first step; The Omnivore’s Dilemma is the most comprehensive source. My point here is that I did not choose to remove myself, as much as possible, from the industrial food system solely to reduce emissions. I did it because I think this industry is sick and broken in just about every aspect of its existence. Therefore, I think it’s worth doing even if the food industry isn’t the biggest contributor to our carbon footprint.

But back to the question... I tried to find a plot that compared greenhouse gas (GHG) emissions by usage type (food industry versus heating and cooling, for example) but was unsuccessful. The plots I did find were unclear. For example, one plot had emissions for transportation and electricity along side industrial, commercial, and residential categories. It makes me wonder what kind of transportation emissions are not industrial, commercial, or residential. I did find a plot that shows emissions for the food industry specifically:

This suggests that food production has a much greater climate impact than food transportation in all sectors and that the impact from red meat is by far the largest. As the commenter suggested, reducing food miles may not be the most effective way to reduce the climate impact involved with your food consumption. Rather, you should probably focus on replacing much of the industrial red meat in your diet with vegetables.

One last thing on this issue, I found this article by Michael Pollan in which he claims that:

“After cars, the food system uses more fossil fuel than any other sector of the economy — 19 percent. And while the experts disagree about the exact amount, the way we feed ourselves contributes more greenhouse gases to the atmosphere than anything else we do — as much as 37 percent, according to one study.”

The article was written to the President-elect and outlines an approach to changing the industrial food system to the benefit of people, animals, and the environment. It’s long, but I think a very worthwhile read.

Is local food better for the environment?

The simple answer is maybe. When it comes to fresh produce at least, food miles is an incomplete metric. As a reader pointed out, it depends heavily on your local food region. The SF bay area can likely supply a much larger and more diverse set of goods with fewer destructive inputs than Phoenix, Arizona or New York City. Plus, the impact of food miles depends heavily on the method of transportation. Moving food by ship or rail is much more efficient than doing so by truck. A total impact score, which would combine the production and transportation impact of a food from farm to consumer, would be a more useful metric. Several studies discussed in this article found that, when the total impact of a food item is evaluated, local food does not always win out over foods that are extremely not local. Here are some excepts from the article describing the findings:

Many factors influence the carbon footprint of a product: water use, cultivation and harvesting methods, quantity and type of fertilizer, even the type of fuel used to make the package. Sea-freight emissions are less than a sixtieth of those associated with airplanes, and you don’t have to build highways to berth a ship. Last year, a study of the carbon cost of the global wine trade found that it is actually more “green” for New Yorkers to drink wine from Bordeaux, which is shipped by sea, than wine from California, sent by truck. That is largely because shipping wine is mostly shipping glass. The study found that “the efficiencies of shipping drive a ‘green line’ all the way to Columbus, Ohio, the point where a wine from Bordeaux and Napa has the same carbon intensity.”

The environmental burden imposed by importing apples from New Zealand to Northern Europe or New York can be lower than if the apples were raised fifty miles away. “In New Zealand, they have more sunshine than in the U.K., which helps productivity,” Williams explained. That means the yield of New Zealand apples far exceeds the yield of those grown in northern climates, so the energy required for farmers to grow the crop is correspondingly lower. It also helps that the electricity in New Zealand is mostly generated by renewable sources, none of which emit large amounts of CO2. Researchers at Lincoln University, in Christchurch, found that lamb raised in New Zealand and shipped eleven thousand miles by boat to England produced six hundred and eighty-eight kilograms of carbon-dioxide emissions per ton, about a fourth the amount produced by British lamb. In part, that is because pastures in New Zealand need far less fertilizer than most grazing land in Britain (or in many parts of the United States). Similarly, importing beans from Uganda or Kenya—where the farms are small, tractor use is limited, and the fertilizer is almost always manure—tends to be more efficient than growing beans in Europe, with its reliance on energy-dependent irrigation systems.

Williams and his colleagues recently completed a study that examined the environmental costs of buying roses shipped to England from Holland and of those exported (and sent by air) from Kenya. In each case, the team made a complete life-cycle analysis of twelve thousand rose stems for sale in February—in which all the variables, from seeds to store, were taken into consideration. They even multiplied the CO2 emissions for the air-freighted Kenyan roses by a factor of nearly three, to account for the increased effect of burning fuel at a high altitude. Nonetheless, the carbon footprint of the roses from Holland—which are almost always grown in a heated greenhouse—was six times the footprint of those shipped from Kenya. Even Williams was surprised by the magnitude of the difference. “Everyone always wants to make ethical choices about the food they eat and the things they buy,” he told me. “And they should. It’s just that what seems obvious often is not. And we need to make sure people understand that before they make decisions on how they ought to live.”

Clearly, a comprehensive impact score would be a more useful metric than food miles. However, it may be impractical to compute especially for processed items that include many ingredients from different sources. And perhaps that brings us to the true value of local food. Rather than arguing about which fresh, whole produce item impacts the environment the least, we should really be considering local food as an alternative to processed, packaged, food-like products. For example, it may be difficult for an individual person to evaluate the relative merits of strawberries purchased at a local farmer’s market or shipped in from another region without knowing the production issues involved with making strawberries grow in each region, the practices of the farm from which they came, or the methods of transport. However, I think it is clear that buying fresh, whole strawberries to put in your cereal has less of a negative impact than buying cereal with processed strawberries already inside. At some point, a cereal-company employee had to make the same decision as my fictional strawberry consumer as to where to buy the strawberries. But instead of those strawberries traveling directly from farm to consumer, they first have to be shipped to the cereal plant and then be packaged and distributed and ultimately arrive at the supermarket along with all of the other ingredients in the cereal. Those strawberries will thus travel many more miles and impact the environment more than the same strawberries delivered directly to the consumer.

There are clearly situations when food that has traveled less is better for the environment. In particular, local produce is almost certainly better than produce incorporated into a processed food-like product. It is also likely to be better than well-traveled food in regions where food is easily grown. Certainly, to draw upon the above examples, eating local lamb or apples while living in New Zealand is clearly much better than importing them from England! It would be very useful for the scientists who do these life-cycle-analysis studies to create best and worse local food lists for different regions that could guide our shopping decisions. Until then, the following guidelines (roughly in order of importance based on my opinion) seem like the most useful:

(1) Replace industrial, red meat with vegetables as often as you can.

(2) Buy whole, fresh foods rather than processed ones.

(3) If possible, shop at a farmer’s market that provides information on (or restricts) the farming practices of its vendors in addition to food miles.

(3) Use common sense. If you live in an area that easily produces food, stick with local (preferably organic) produce. Otherwise, eat non-local fresh fruits and vegetables to keep yourself healthy!

(4) Pay attention to the season. Tomatoes do not grow in California in January. If you find them in the store, they either traveled a long distance or were produced in hot houses, which require a lot of extra electricity. Try something seasonal instead.

“Of course the difficulty with organic is that it doesn't always mean the same thing. At least local usually means less than 100 miles away.”

This one was pretty easy to check (yay!). Actually, USDA Certified Organic represents specific regulations that must be followed before a food item can be labeled as such. You can find out exactly what it means at the USDA National Organic Program website. As for local, it typically indicates a 100-mile radius. However, there is no official definition. I read that some food is described as local if it is sold in the same state as it was grown; great if you're in Rhode Island, not so much in Texas.

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