Page 292 - Environment: The Science Behind the Stories

In 2008, environmental scientists Christopher Weber and H. low, you will get a better idea of how our dietary choices con-
Scott Mathews conducted a thorough life-cycle analysis of tribute to climate change.
U.S. food production and delivery. By filling in the table be-

Total emissions Emissions Percent emissions
1
1
Food Type across life cycle from delivery 2 from delivery 2
Fruits & vegetables 0.85 0.10 11.8
Cereals & carbohydrates 0.90 0.07
Dairy products 1.45 0.03
Chicken/fish/eggs 0.75 0.03
Red meat 2.45 0.03
Beverages 0.50 0.04
1 Emissions are measured in metric tons of carbon-dioxide-equivalents, per household per year.
2 “Delivery” means transport from producer to retailer.
Weber, C.L., and H.S. Mathews, 2008. Food-miles and the relative climate impacts of food choices in the United States. Environmental Science
and Technology 42: 3508–3513.

1. Which type of food is responsible for the most green- 3. After measuring mass, energy content, and dollar value
house gas emissions across its whole life cycle? Which for each food type, the researchers calculated emissions
type is responsible for the least emissions? per kilogram, calorie, and dollar. In every case, red meat
2. What is the range of values for percent of emissions produced the most emissions, followed by dairy products
from transport of food to retailers (delivery)? Weber and chicken, fish, and eggs. They then calculated that
and Mathews found that 83% of food’s total emissions shifting one’s diet from meat and dairy to fruits, vegeta-
came from its production process on the farm or feed- bles, and grains for just one day per week would reduce
lot. What do these numbers tell you about how you emissions as much as eating 100% locally (cutting food-
might best reduce your own footprint with regard to miles to zero) all the time. Knowing all this, how would
food? you choose to reduce your own food footprint? By how
much do you think you could reduce it?

STUDENTS INSTRUCTORS
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etext, and the Study Area with practice tests, videos, current graded activities, current events, videos, and reading questions
events, and activities. that you can assign to your students, plus Instructor Resources. CHAPTER 10 • A g R i C ulT u RE , Bi o TECH nology, A nd THE Fu T u RE o F Food

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