According to a recent article in the respected British medical journal Lancet, climate change is the biggest global health threat of the 21st century. We physicians need to speak out on this. The Aug. 5 Sunday New York Times devoted the entire magazine section to a comprehensive article on climate change. The title is “Thirty years ago, we could have saved the planet.” At one time climate change was a bipartisan issue — since it affects all of us it still should be. The article makes it disturbingly clear that the planet our children and grandchildren will inherit won’t be as livable as it is today, and eventually human civilization will be at risk.

Therefore, it’s imperative that people become aware of how their food choices affect the environment. There’s no question that eating plants, which are at the bottom of the food chain, has much less of an environmental impact than eating animal products. The non-profit Environmental Working Group (EWG) notes that “production, processing and distribution of meat requires huge outlays of pesticide, fertilizer, fuel, feed and water while releasing greenhouse gases, manure and a range of toxic chemicals into our air and water.”

A recent article in Scientific American noted that raising red meat such as beef and lamb is responsible for 10-40 times the greenhouse gases compared to growing vegetables and grains. It takes 25 kcal of fossil fuel energy to produce 1 kcal of animal protein, whereas it takes 2.2 kcal to produce 1 kcal of protein from grains. The number of kilograms of greenhouse gas resulting from production of 100 grams of various foods is: beef-50; cheese-11; poultry-5.7; tofu-2.

A recent article produced by the University of Oxford in collaboration with the LCA Research Group of Switzerland, and published in Forbes, notes that meat and dairy provide 18 percent of all calories consumed on the planet but account for 83 percent of the farmland and 60 percent of greenhouse gas emissions. It also points out that if the entire world cut out meat and dairy, global farmland would decrease by 75 percent (the equivalent of the land mass of the U.S., China, European Union and Australia combined would go from farmland back to its natural state).

Other environmental issues associated with consumption of animal products include:

• A 2009 study indicated that four-fifths of deforestation across the Amazon is linked to cattle ranching.

• Factory farms create huge amounts of sewage waste, which causes water pollution.

• Antibiotics are used in factory and even conventional farming to prevent disease and to make animals grow faster — which contributes to antibiotic resistance.

• As the world gets hotter and more crowded, water is becoming scarcer. Raising a pound of beef takes multiple times more water than raising a pound of kale.

• Cattle are responsible for 20 percent of the world’s methane — a particularly potent greenhouse gas.

Authors of the Forbes article conclude by saying this: “A vegan diet is the single biggest way to reduce your impact on Earth. Buying an electric car, lowering your thermostat, taking quick showers all pale in comparison to simply eating less meat and dairy. Particularly, reducing the consumption of beef, dairy and pork cuts out some of the largest culprits.” We know that a plant-based diet is best for optimal human health — it is also best for health of our planet. As Dr. Greger puts it on nutritionfacts.org, “meat is heat.”

Dr. Feinsinger, who retired from Glenwood Medical Associates after 42 years as a family physician, has a nonprofit Center For Prevention and Treatment of Disease Through Nutrition. He is available for free consultations about heart attack prevention and other medical issues. Call 970-379-5718 for an appointment. For questions about his columns, email him at gfeinsinger@comcast.net.