Your Food Choices Affect the Earth's Climate
Every action has a cost, even for growing food and delivering it to your dinner plate. A team of researchers has found that meat production releases more climate-warming pollution than it does when producing fruits, vegetables, nuts and grains. Their calculations suggest that people could do a lot to slow global warming if they limited how much meat they eat.
There are plenty of "costs" of food. As to the visible costs, people pay money for the food as well as the fuel needed to get groceries to the store or restaurant. However, producing foods also takes resources, for example, the water used to irritate (灌溉) crop fields or the fertilizer and chemicals used to promote plant growth and fight pests.
Peter Scarborough at the University of Oxford in England decided to calculate some of the less-visible pollution created by food production. His team focused on greenhouse gases emitted through the production of our food, including carbon dioxide(CO2), methane(甲烷) and the nitrous oxide. All three gases are important. While CO2 is the greenhouse gas released in the highest volume, methane and nitrous oxide stay in the atmosphere far longer than CO2 does. As such, they are more powerful in warm the earth's atmosphere.
They used a computer to change the methane and nitrous-oxide emissions for each person's diet into its carbon dioxide "equivalent." That's the amount of CO2 needed to warm Earth's atmosphere by the same amount as the methane or nitrous oxide would.
As for the calculations of the carbon dioxide "equivalent(等量)", in the 1990s, a survey asked65,000 adults what they typically had eaten throughout the past year. Scarborough's team fed those data into a computer and then included the amount of green house gases linked with producing nearly100 common foods. Then the computer matched those green house-gas amounts to the mix of foods each person had reported eating.
It shows that the diet of someone whose meals included an average of 50 to 99 grams of meat each day would be responsible for the daily release of 5.6 kilograms of CO2 equivalent while those vegans had the lowest diet-linked greenhouse-gas emissions (2.9 kg of CO2 equivalent).
Its authors conclude that reducing the intake of meat and other animal-based products can make a valuable contribution to climate change reduction. And compared to meat, more plant-based food calories can be grown on more lands with less water and other resources. In places where many people are going hungry, raising meat may make it harder to ensure that everyone gets enough to eat.
Plant-based food can adapt to more types of lands than meat, but they may have a higher requirement of water and other resources, which can be a disadvantage of such food.
