Greener Diet

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. Last week, scientists attending the American Association for the Advancement of Science meeting in Chicago presented new studies showing how food and its production affect the globe and its warming climate. The researchers had some bad news for meat-eaters (which is good news for cows!). They also offered some suggestions for how to eat in a more environmentally friendly way.

You’ve probably heard of global warming: For many years, scientists have warned that our planet is getting warmer. If current trends continue, then animals may start to die off and life could get very difficult for everyone. The temperature is on the rise because for more than a century, human kind has been releasing massive amounts of gases into the atmosphere, called “greenhouse gases.” These gases surround the planet and keep heat from escaping the atmosphere. You can think of them as a blanket for the Earth that traps heat. One of these greenhouse gases is carbon dioxide.

What does this have to do with food? A big chunk of the carbon dioxide that we put in the atmosphere every year comes from the process of making and eating food, the scientists reported in Chicago. The production of meat contributes a lot of that carbon dioxide. 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 manure is a major source of methane — an especially potent greenhouse gas. The cow has to be slaughtered. The meat has to be processed and shipped to a consumer, 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 taken a heavy toll on the environment. According to Ulf Sonesson of the Swedish Institute for Food and Biotechnology in Goteborg, Sweden, the process of making a one half-pound all-beef burger adds the equivalent (made up of other greenhouse gases) of about 19 times that hamburger’s weight in carbon dioxide.

The message from the research is clear: We can drastically reduce the production of global-warming gases by eating less beef. (That’s healthier, too, since Americans eat twice as much beef as is advised by the U.S. Department of Agriculture.) 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. Nathan Pelletier, a scientist Dalhousie University in Canada, reported that if everyone in industrial countries (like the United States) substituted chicken for beef, we would cut meat’s contribution in these countries to the greenhouse warming of Earth’s air by more than half.

All kinds of meat, the scientists reported, 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 or equivalent warming gases into the air. So shifting our diet to less meat and more vegetables, as it turns out, may do the world some good.