Carbon footprint solution in diet

UNDER THE MICROSCOPE:WE ARE all frequently exhorted to reduce our carbon footprint; that is, the amount of greenhouse gases, in equivalents of kilograms of carbon dioxide, that our personal lifestyles cause to be emitted to the atmosphere annually.

And we all know that we could reduce this footprint by cutting down on air and car travel, driving small cars or hybrid cars, insulating our homes, and so on. But did you know that the single most effective thing most of us could do in this respect is to change our diets to low-carbon diets? This would achieve two objectives in one, not only greatly reducing our carbon footprint but also providing us with a much healthier diet.

Agriculture contributes about 30 per cent of global greenhouse-gas emissions – these are the gases, principally carbon dioxide but also methane, nitrous oxide and so on, that can artificially warm our world. This is much more than the amount emitted by transportation. It has been calculated that the average American family emits 2.2 tons of carbon dioxide annually from driving and 2.8 tons of carbon dioxide from eating.

Meat production, particularly beef, is a very heavy emitter of carbon dioxide. The United Nations Food and Agriculture Organisation reported in 2006 that current production levels of meat contribute between 14 and 22 per cent of the carbon dioxide equivalent gases the world produces every year. Producing 0.25kg of mince releases as much greenhouse gases to the air as driving an average car for 14km. This is four times the carbon dioxide-emitting potential of producing 0.25kg of pork, 14 times the carbon dioxide-emitting potential of producing 0.25kg of chicken, and 50-60 times the carbon dioxide-emitting potential of producing 0.25kg of fruits/vegetables.

The global food system is enormous and highly energy-intensive. Almost 40 per cent of the world’s land is devoted to agriculture. Much of this land was forested but cleared for agriculture, a double-whammy for carbon emissions since trees remove carbon dioxide from the air. Fertilisers, farm machinery, shipping and trucking to grow the food and bring it to our plate each have large carbon footprints.

However, the good news is that some foods produce much smaller carbon footprints than others and have the great added bonus that they are also much better for your general health. Foods with the largest carbon footprints, such as beef, pork, dairy produce and processed foods, also tend to be high in fat and calories, whereas the foods with much lower carbon footprints, such as fruits/vegetables, fish and lean meats (chicken, for example), are also much lower in fat and calories. The low-fat, low-calorie foods are much better for your cardiovascular health than the high-fat, high-calorie foods.

HERE IS Acomparison of some common lower- and higher-carbon foods with regards to calories, grams of fat and carbon footprint represented by a 100g serving. The first number within the brackets after each food is calories, the second is grams of fat and the third is carbon footprint (kg of carbon dioxide): steamed vegetables (67, 0.12, 0.07), pasta (136, 1.1, 0.16), grilled chicken (171, 3.8, 0.55), cheese (415, 34, 0.91), grilled steak (316, 22.3, 4.4).

Beef and dairy production emit particularly high levels of greenhouse gases. This is particularly true when the animals are raised in Confined Animal Feeding Operations (Cafos) where they are fed on corn or soya beans, which must be fertilised, irrigated, processed into animal feed and transported to the Cafo. In 2005, Cafos accounted for 74 per cent world poultry production, 50 per cent pork, 43 per cent beef and 68 per cent of egg production. Grass-fed beef produces 40 per cent less greenhouse-gas emissions. Both grain- and grass-fed cattle belch out methane, a greenhouse gas that is 20 times as warming as carbon dioxide. Raising animals also produces numerous wastes that give rise to greenhouse gases. Livestock production alone produces 18 per cent of worldwide greenhouse-gas emissions. The simplest way we can help to reduce carbon dioxide and methane emissions is by eating less beef, lamb, pork and cheese, and when we do eat these foods to seek out locally produced grass-fed options.

So, to help to slow down global warming you do not have to spend lots of money installing solar panels, purchasing hybrid cars and so on. You can exert a very significant effect simply by eating lower off the food chain (more fruits and vegetables, less meat, particularly beef, and dairy). This will not only keep you cooler but healthier as well. At present, world beef production is increasing at the rate of 1 per cent per year.

This is partly due to population increase and partly due to increased consumer demand. It is time to significantly reduce this demand.

William Reville is associate professor of biochemistry and public awareness of science officer at UCC –

http://understandingscience.ucc.ie