The amount to beef in our diet has increased tremendously over the last few decades. From 1961 to 2011 the amount of meat consumed globally almost tripled. Once a luxury, it is now a staple household food. As poor countries grow in wealth, their new middle classes demand more meaty meals, in particular steak.
The following blog post is an extract from Food and Climate Change Without the Hot Air by S L Bridle, formerly a professor of Astrophysics, now professor of Food, Climate and Society at the University of York. As an inquisitive eater, Bridle hopes the book will equip people with the knowledge they need, so they can decrease their diet’s environmental impact and play their part in preventing climate change.
On the eve of Cop 26, this blog post is going to focus on beef because it is one of the highest status meat meals with the highest environmental cost. We’ve already focused on the environmental impact of dairy cows and rumination, but what about “prime” beef herds which are raised for butchery, not milk?
A mother cow usually has a new calf every year, and that calf is fattened for about one year before being slaughtered for about 250 kilograms of beef meat (about four times the weight of a human). On average a calf eats over 40,000 kCal each day to grow big and strong, and we have to also take into account a similar number of calories eaten each day by the mother cow. In total the calf and mother cow eat about thirty times the average calorie intake of one human each day.
A beef cow produces about half their own body’s volume of methane each day. However, methane’s potency as a greenhouse gas means that this amount of methane causes the same warming effect as 10kg of carbon dioxide. Each day the calf grows nearly 700 grams (24 oz) of extra flesh that can become beef meat, which would be enough for three large (8 oz) steaks. This means that just from the methane burps alone, beef causes 14 times its own weight in emissions. It also means that only about 2% of the calories eaten by the cow make it through to our stomachs; this is the least efficient of all the animal products considered in Food and Climate Change Without the Hot Air. However, we should note that pasture-fed cows are creating a nutritious food that we can eat from the most abundant yet effectively inedible-to-humans food source on the planet (grass).
Where do all the other calories go, if not into the beef? Most of the calories come out of the other end of the cow, as manure. This is a good fertilizer for crops, if transported to the right place. Unfortunately it can also decompose into methane, if left without sufficient oxygen to help it decompose into carbon dioxide. While the manure is an excellent fertilizer because it contains a lot of nitrogen, this nitrogen causes nitrous oxide emissions whether or not the manure is being used to grow crops. The exact emissions depend on how dry the manure pile is, and how it is spread, but manure helps bring the total emissions for beef to around 46 times the weight of the portion.
1 g steak = 46 g emissions
Steak’s environmental impact
We can now calculate the global warming impact of the highest emissions regularly eaten meal: a large steak. A 225 g (8 oz) steak causes about 10 kilos of greenhouse-gas emissions, which is three times larger than a budget of 3 kg of emissions for a whole day. If everyone in the world ate such a large steak every day then the steaks alone would use up the remaining 1.5°C carbon budget before 2040.
Here are some other comparisons. Eating one large steak is equivalent to driving a fossil-fuelled car about 70 kilometres (40 miles), which is a relatively short daily commute to work in many countries. Alternatively, taking one transatlantic flight every year is equivalent to eating one large steak a day. So we should think twice about ordering a steak on a regular basis, but at the same time look at our non-food emissions.
Lower impact beef
The climate impact of efficiently produced prime beef has roughly equal contributions from the calf and the mother. But what if the mother cow were also producing milk during most of her one year gap between calving, and if we slaughtered the mother for beef at the end of her milk-producing life?
Furthermore, male dairy calves aren’t needed for milk production and so are often killed young (producing a negligible amount of meat). Fattening them up for meat instead would produce a lower-emissions piece of beef, which can be as much as two times better for the climate than prime beef.
In fact, about half of all beef already comes from dairy cows. This can significantly reduce the environmental footprint of beef, by two or more times, depending on whether the male calves are fattened and how the emissions are allocated between the milk and beef.
Based on the current quantities of meat from dairy herds, we would have to roughly halve our beef consumption to remove the demand for dedicated prime-beef herds. To support dairy beef and encourage the most efficient practices, we also need more information on the meat we are buying, at very least we need the packet to tell us what kind of herd the meat comes from!
So what’s a good substitute for beef in mince dishes like spaghetti bolognese? Lamb is delicious but it has about the same emissions as beef, because sheep have similar stomachs to cows (1 g lamb = 46 g emissions).
Pork causes fewer emissions than beef (1 g ham = 11 g emissions), but chicken is lower still (1 g chicken = 9 g emissions). A chicken spaghetti bolognese causes three times lower emissions than a prime beef spaghetti bolognese. Switching to beans or lentils halves the emissions again to 1 kg per person.
You can read more about how to change your diet to save the planet in ‘Food and Climate Change Without The Hot Air’, available for purchase as a paperback where all good books are sold, or you could buy the ebook for £/$ 0.00 (yes, really nothing to pay.) Get the Kindle ebook here and the EPUB here.