Think about what you had for lunch: Was it a hamburger? A chicken sandwich? Barbecue? What about vegetables? Would it surprise you to learn that what you eat can affect the whole planet? It can—in a big way. New studies show how food and its production affect the globe and its warming climate. You’ve probably heard of global warming : The temperature is on the rise because humankind has been releasing (排放) amounts of gases into the atmosphere. One of these greenhouse gases is carbon dioxide（二氧化碳）. What does this have to do with food ? A big part of the carbon dioxide that we put in the atmosphere every year comes from the process of making and eating food. The production of meat contributes a lot of that carbon diode. And much of meat’s contribution comes from beef , which is responsible for releasing even more warming gases into the atmosphere. The process of making a hamburger ,for example, requires a lot of energy. A cow has to be fed and raised on farmland, and cow waste is a major source of methane (沼气) — an especially powerful greenhouse gas. The cow has to be killed. The meat has to be processed (加工) and shipped to a shop, which takes fuel . Most of the cow won’t even be used for meat that people eat. By the time a hamburger finally lands on a dinner plate, it has made a heavy effect on the environment. We can reduce the production of global-warming gases by eating less beef .Other kinds of meat like pork and chicken do less harm to the environment—at least in terms of the amount of greenhouse gases released. All kinds of meat are harder on the planet than vegetables. To grow and eat a pound of potatoes, for example, sends less than one-quarter pound of carbon dioxide into the air. So changing our diet to less meat and more vegetables, as it turns out, may do the world some good. 小题1:The questions asked in the first paragraph are used to _____.
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