I'm a professor at U Michigan and lead a course on climate change problem solving. These articles often come from and contribute to the course.
By: Dr. Ricky Rood , 3:38 AM GMT on April 30, 2013
We Are What We Eat: What Can I Do? (5)
Revised: May 9, 2013
This is the continuation of a series in response to the question, “What can I do about climate change?” Links to the previous entries are listed at the end.
Last week I made a list of categories to classify the types of actions that we can take to reduce greenhouse gas emissions. The second item on that list is food. But first, I want to start with some more sets of categories.
When we think of fossil fuels, coal, oil and natural gas come to forefront. We often think of coal as dirty and natural gas as clean, in terms of air quality, climate change and general environmental damage. All of these forms of fossil fuels emit carbon dioxide when they burn, and that carbon dioxide is for practical human time in either the atmosphere or ocean permanently. Therefore we can’t simply replace coal and oil with natural gas and declare that we will avoid global warming.
If we examine how we use energy, then those uses can be divided into three categories: power generation, transportation and direct use for heat. For the past few decades, coal has dominated power generation and petroleum has dominated transportation. All three contribute to direct use for heat. Recently in the U.S., natural gas has been replacing coal for power generation, but worldwide, coal is still the dominant fuel (natural gas and coal, TON, NPR). Oil dominates transportation.
Taking another cut through our energy use, we can categorize use as residential, commercial, industrial and for transportation. Industrial uses create products from raw materials: manufacturing, cement making, mining and agriculture. Commercial uses include shops, government buildings and where governments spend money. Residential and commercial uses include a large part of electricity, heating and cooling of buildings, and heating of water. An interesting point: next to the burning of fossil fuels, cement making is the largest nonagricultural source of carbon dioxide emissions. It’s on the order of 5 percent.
If we return to the question of “What Can I Do?,” then the items discussed in the previous entries on efficiency focus primarily on the better management of buildings (residential and commercial) as well as on +choices in transportation. In fact, an alternative way to categorize use is for buildings, transportation and industry. If one were to think about government regulation, then emissions from coal-fired power plants are relatively easy to target because there are not that many power plants and they don’t move around. Transportation is harder to regulate because there are, globally, billions of cars and trucks and they do move around. The different categories I have described demonstrate both the easy opportunity for regulation, power generation, and the challenges of climate policy – that there is no single thing to fix the problem of greenhouse gas emissions.
Now to food – If we were to make a special food and agriculture category, then agriculture is responsible for about the same amount of emissions as, say, transportation or heating. Now, however, we have to become more holistic about what we mean by emissions. For agriculture, we have carbon dioxide emissions, which come mostly from deforestation. Cutting and burning forests to make new rangeland for cattle make up about 10 percent of the total annual carbon dioxide emissions. There is some emission from the use of fossil fuels for tractors and irrigation, and about half of the agricultural carbon dioxide fossil fuel emissions come from the manufacture of fertilizer. There are also other land use and soil management decisions made in agriculture that affect carbon dioxide emissions.
Beyond carbon dioxide, agriculture is responsible for about a third of methane emissions and close to two-thirds of the nitrous oxide (N2O) emissions. These are greenhouse gases that are more potent than carbon dioxide; they are in much lower concentrations in the atmosphere.
So, what we eat can make a difference. When I was in college in the 1970s, I was introduced to Frances Moore Lappe’s book, Diet for a Small Planet. What I remember from that book was that if you took all of the calories needed to grow a pound of beef and instead feed those grains to people, you could feed many more people than you could with a pound of beef. It was my first introduction to sustainability. It takes much land and energy to make the well-marbled porterhouses that my father fed me in one-pound servings. No matter how you count, livestock production, in particular, beef production, releases a lot of greenhouse gases.
There are many marketing appeals in food and food supply. These appeals are to make personal decisions that affect the world, and individual choices the public makes about food and food supply do affect the world. We have appeals to buy grass-fed beef, organic meat and produce, locally produced and sustainable agriculture. We are faced with issues of packaging, preprocessing, natural, raw and prepared. There are no easy algorithms. In February, an apple from Chile might take less energy in transportation than an apple from Virginia takes in cold storage. We demand fresh fruit, vegetables and meat all winter. We demand exotic spices, fine coffee, tea and chocolate. The global demand for meat and nonlocal food increases as the world’s wealth increases.
So what rules of food selection matter? My personal evaluation is that reducing meat consumption is at the top of the list, and at the top of the meat list is beef. Pasture-raised might be better than feedlot, but life cycle studies show that beef is a relatively inefficient use of energy. Chicken is far more energy-efficient. Should we choose sustainable, local or organic meat and produce? From an emissions point of view, I hear sustainable advocated as best if there are actual standards and certification of sustainability--then local, then organic. I have made the controversial claim that since our current practice of organic, local and sustainable agriculture demands high payment for produce and meat, and since most of our generation of money requires high fossil fuel energy use, there is a hidden cost to the climate that comes from high-value crops.
It’s not easy, but what we eat does make a difference to the environment. We usually think of this difference in terms of pesticides, herbicides and erosion, but there is also a climate impact. And as is often the case, the connection is indirect, far in the future and difficult to know how to value.
Note: The source of much of the material in this entry is based on Livestock’s Long Shadow a 2006 publication of the Food and Agriculture Organization of the United Nations. There has been much criticism of this report, especially in its calculation of the emissions of the transportation sector. The original authors did modify their specific statements about transportation. As noted in the next blog in this series, there is substantial controversy about the impact of agriculture. My evaluation is that the agriculture numbers in this report are as robust as any I know. My opinion would be that the agriculture emissions in this report are more likely an underestimate than an overestimate. As for comparisons to other sources of emissions, when fossil fuel emissions are broken down as described in this blog, the different sectors, residential, commercial, transportation and industrial, are all large and no single one is dominant. Therefore, the conclusion that agriculture is comparable to these sectors seems reasonable.
Previous Entries in the Series
Setting Up the Discussion Deciding to do something, definition of mitigation and adaptation, and a cost-benefit anchored framework for thinking about mitigation
Smoking, Marriage and Climate Behavioral changes and peer pressure
Organizing and Growing Individual Efforts A little detail on efficiency and thinking about how individuals can have more impact than just that of a single person
The Complete List Eight categories of things we can do to reduce greenhouse gases
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