Eating a juicy steak is worse for the environment than frying up some tofu: that should come as no surprise. Going vegan can greatly cut the carbon footprint of your diet. But what about the fewer calories, and lower levels of protein, found in most plant-based foods when compared with meat?
To make the relative carbon impact of foods easier to understand, The Economist proposes a banana index (指数). It compares popular foodstuffs in three aspects—weight, calories and protein—compared to the humble banana, a fruit of middling nutritional value and impact on weather conditions.
Indexing greenhouse-gas emissions to a single food gives a sense of how different foodstuffs rank. Unfortunately for carnivores (食肉动物), beef is bad for the environment no matter how you slice it. Producing one kilogram of mince (馅) causes as many emissions as 109kg of bananas (call it a “banana score” of 109). As for nutritional value, beef’s banana score falls to 54 (one calorie of beef mince causes 54 times as much carbon emissions as one calorie of banana). By protein, it scores seven.
Poultry (家禽) scores 11 bananas by weight and four by calorie. However, as a source of protein, it is more carbon-friendly than bananas: poultry protein emits just three-fifths of the same amount of banana protein. The same applies to salmon. Unsurprisingly, plant-based alternatives to meat do even better: a meat-free burger, for instance, scores just one-fifth of the emissions of bananas per gram of protein.
Our banana index relies on average emissions for a given food. In the real world some producers are more climate-friendly than others, and some foods travel farther to consumers. Our banana index also does not capture other environmental impacts, such as land and water use (though here too, beef tends to perform poorly).
Voting in Europe suggests that most consumers want to be more climate-friendly—and with food production responsible for perhaps a quarter of global emissions, eating with the climate in mind would make a difference. Three-quarters of the respondents said they want labels that would explain the climate impact of their food. In the meantime, our banana index might help.
12. What’s the most likely reason for bananas to be chosen as an object of reference?
A.Bananas have fewer calories and less protein. |
B.Bananas are a humble fruit. |
C.Bananas have the least impact on the environment. |
D.Bananas are of medium climate effect and nutrition. |
13. According to the index, which one is more carbon-friendly as a source of protein?
A.Beef | B.A meat-free burger | C.Poultry | D.A banana |
14. Which aspect of the index does paragraph 5 focus on?
A.Its drawbacks | B.Its benefits |
C.Its practical meanings | D.Its principles |
15. What does the passage mainly talk about?
A.An approach to assessing nutritional value of food |
B.A way to measure the climate impact of food |
C.A great indicator of greenhouse-gas emissions |
D.A big helper in deciding what to buy |