The Natural Resources Defense Council recently released a report looking at the climate-damaging effects of the foods we buy, prepare and eat everyday. The study looked at 197 food items and tracked their climate damage based on the CO2 released per kilogram of that food produced. The data was collected from the USDA's Economic Research Service and information collected from 2005 to 2014. Certain food items, such as those that are hard to come by, hard to avoid or are ingredients in other products, were omitted like lard, dry milk and palm oil.

Beef

Beef is known as the most climate-damaging food in the world. The production of a single kilogram of beef results in 26.5 kgs of CO2 emissions. Animal agriculture, like the production of beef, is responsible for 14.5% of emissions worldwide but beef is five times more damaging than chicken or turkey.

So why is beef so bad? The production of beef requires lots of pesticides and fertilizer, which use fossil fuels. The digestive system of cows also produces methane, which is a very powerful greenhouse gas.

Lamb

Like beef, lamb, another red meat, is also incredibly damaging to the environment. 22.9 kg of emissions are created for every kilogram of lamb produced. The food required to feed animals like lambs and cows is very resource intensive and adds to their climate-damaging effect. Fertilizer and manure used to produce the corn and soy that these animals eat releases nitrous oxide, a pollutant that is 298 times more powerful than carbon dioxide.

Butter

Butter comes in as the third most climate damaging food, related to the fact that it, like beef, comes from cows. One kilo of butter produces 12 kilos of CO2 emissions. Butter is the most climate damaging of all dairy products because of the energy needed to produce it. The production of butter involves separating raw milk, pasteurizing the cream, cooling the cream, ripening and churning.

Shellfish

Coming in just under butter, shellfish is the fourth most damaging food for our environment. The production of a kilogram of shellfish produces 11.7 kilograms of CO2 emissions. However, thanks to the changing diet of Americans, less climate-damaging food like shellfish is being consumed more today.

Cheese

Another dairy product to add to the list, cheese on average creates 9.8kg of CO2 emissions per kilogram of cheese produced. This is an average as different types of cheeses contribute different amounts of emissions. For example, cheeses that are flown in and transported from abroad have a much higher climate damaging factor due to the emissions created by travel.

Asparagus

Asparagus is the only vegetable to crack the top ten of the most climate damaging foods. Asparagus produces an alarming 8.9 kg of emissions per kilogram of asparagus produced. But why is this vegetable so high on the list? The increased emissions are due to travel. Most of America’s asparagus is flown in from South America, as opposed to other produce which can be driven from Mexico or other parts of the US.

Pork

A kilogram of pork is responsible for producing 7.9 kilograms of CO2 emissions. However, from 2005 to 2014 the American diet has seen a decrease in pork. This reduction in pork consumption has contributed to the avoidance of 271 million tons of climate damaging pollution.

Veal

Joining the other red meats on this list, veal produces 7.8 kgs of emissions per kilogram of veal. The reason that veal is not as damaging for the climate as beef is because the calves are killed earlier, at approximately 20 weeks, instead of beef cows, which are typically killed at 18 months.

Chicken & Turkey

Chicken and turkey both create the same amount of CO2. Just over 5 kilograms of CO2 emissions are produced for each kilogram of chicken or turkey. But like pork, the consumption of chicken and turkey is decreasing and leading to an overall reduction in food-caused climate pollution.