Diet for a cooler planet.

Our planet just experienced the warmest winter in the 105 years during which records have been kept.

According to James Hansen, who heads NASA's Goddard Institute for Space Studies, "if further global warming reaches 2 or 3 degrees Celsius [4 or 5 degrees Fahrenheit], we will likely see changes that make Earth a different planet than the one we know. The last time it was that warm was ... about three million years ago, when sea level was estimated to have been about 80 feet higher than today."

Fossil fuels--used in coal-burning power plants and gasoline-and-diesel-burning cars and trucks--top the list of problems. But other factors also contribute:

* Population growth: 6.5 billion people--double the population of 1965--now draw down our world's finite resources.

* Higher standards of living: air conditioners, cars, air travel, and other conveniences require fossil fuels.

* Diet: as incomes rise, people replace wheat and rice with meat and dairy foods.

What do more burgers and cheese have to do with climate change?

Between global warming and a lack of land, water, and other resources, the Earth simply can't cope with a worldwide jump in meat and dairy consumption. In 2006, a report by the United Nations Food and Agriculture Organization (FAO) warned:

"Livestock's contribution to environmental problems is on a massive scale and its potential contribution to their solution is equally large. The impact is so significant that it needs to be addressed with urgency."

Livestock not only pollutes our water, air, and soil, said the FAO, it's also "responsible for 18 percent of greenhouse gas emissions ... a higher share than transport."

Cattle belch out huge volumes of methane, a gas that's 23 times more potent at trapping heat than carbon dioxide. Livestock manure is the source of two-thirds of man-made nitrous oxide, a greenhouse gas that's 300 times more potent than carbon dioxide.

Growing corn, soybeans, and hay for live stock feed uses up about half of all U.S. fertilizer, generating large amounts of nitrous oxide. In Brazil, an astounding 70 percent of onetime forest land is being used as pasture and to grow animal feed.

Worldwide, the 34 million acres of trees that are cut and burned each year account for 25 to 30 percent of all the carbon that enters our atmosphere.

Eating less meat and dairy foods is a small step that each of us could take to help slow global warming.

Bonus: switching from meat to beans, nuts, fruits, and vegetables means lower risks of heart disease, stroke, obesity, diabetes, and cancer. (See www.EatingGreen.org to calculate those benefits and to order our book, Six Arguments for a Greener Diet.)

So for the sake of our globe--and our own health--let's all try to eat more plants and less meat.

Michael F. Jacobson, Ph.D.

Executive Director

Center for Science in the Public Interest