These are the most climate-damaging foods

Photos: 10 common climate-damaging foods in the American diet

Beef – Beef is widely recognized as the most climate-damaging of all foods. A 2017 study by the Natural Resources Defense Council on food consumption in the US calculates that each kilogram of beef produces 26.5 kilograms of CO2 emissions -- the highest among all the foods observed in the study, and five times more than chicken or turkey meat.

Animal agriculture is responsible for 14.5% of the world's greenhouse emissions, according to the UN's Food and Agriculture Organization, making it a significant contributor to climate change. Of those emissions, 65% come from beef and dairy cattle.

Reducing beef consumption is an effective way of curbing global emissions. According to the NRDC, Americans now consume 19% less beef than they did in 2005. This is equivalent to a reduction of 185 million metric tons of emissions, or the annual tailpipe pollution of 39 million cars.
But why is beef so bad? "The feed is largely produced using lots of pesticide and fertilizer, which requires fossil fuels," explains Sujatha Bergen, one of the authors of the study. "Also, the digestive system of the cows produces methane, which is 25 times more potent a greenhouse gas than carbon dioxide. And the manure emits additional greenhouse gases."

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Photos: 10 common climate-damaging foods in the American diet

Lamb – Another ruminant, lamb, comes at number two -- confirming that red meat is particularly resource-intensive and, as such, damaging to the environment. For each kilo of lamb meat consumed, there are 22.9 kilos of emissions, the NRDC study estimates.

Meat production also requires large amounts of animal feed, mainly the resource-intensive corn and soy. The synthetic fertilizer and the manure used to grow these also releases nitrous oxide, a climate-warming pollutant 298 times more powerful than carbon dioxide.

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Photos: 10 common climate-damaging foods in the American diet

Butter – The third most damaging food, by some distance, is butter: one kilo of butter equals nearly 12 kilos of CO2 -- about half as many as beef. It belongs to the same supply chain, making dairy and beef cattle an environmentalist's nightmare.

While Americans have greatly reduced their consumption of red meat in recent years, the NRDC reports that butter and other dairy products such as cheese and yogurt actually enjoyed a surge in the observed period, from 2005 to 2014.

Butter is the most climate damaging of all dairy products because there are several steps involved in producing it that are energy-intensive: "For example, butter production requires separating raw milk into low-fat milk and cream, pasteurizing the cream, cooling the cream, ripening and churning," Sujatha Bergen told CNN.

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Photos: 10 common climate-damaging foods in the American diet

Shelllfish – Shellfish costs the environment 11.7 kilos of CO2 for every kilo of food produced, just marginally less than butter. Along with milk, pork, and high-fructose corn syrup -- widely used as a sweetener in soft drinks -- shellfish is among the key foods that Americans are eating less of. Overall, changes in the American diet since 2005 have led to a 10% decrease in per-capita climate pollution related to food, according to the NRDC.

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Photos: 10 common climate-damaging foods in the American diet

Cheese – Another dairy product, cheese, comes in fifth place with 9.8 kg of emissions per kg produced. "Our list is a an average of several common cheeses," explains Sujatha Bergen, "Cheeses that require refrigerated transport or are flown in from abroad, however, tend to have higher climate impacts."

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