The Carbon Footprint of a Burger

20 March 2008

Photo: NiDerLander

We all have become familiar with the method of carbon footprinting. Every product and service we consume has an impact on the atmosphere in terms of carbon emitted. Many of us are accustomed to considering the effects of taking flights or driving cars, but we don't necessarily worry about mundane everyday items. I wanted to find out what's the carbon footprint of the humble takeaway burger?

I am indebted to Jamais Cascio for the method of calculation. I have applied his well-tested US findings to the UK.

The basic statistics were surprisingly difficult to find, but by cross-checking with various sources I am convinced the figures are in the right ball-park.

Firstly we need to find out how many burgers on average a UK citizen consumes. Eric Schlosser in his invaluable book Fast Food Nation estimates that every American eats 1-3 per week. This is higher than UK consumption per head. The UK Expenditure and Food survey suggests 170 kg of takeaway meat consumption person per week. Let's err on the low side and say one 100 gramme burger per week. This is the size of a small hamburger. Some are much bigger – a Burger King Whopper weighs in at 274g.

Photo: Donna Beeler

If we estimate 50 burgers per year then we can do the rest of the calculation.

An important part of carbon footprinting is to ensure that we account for all greenhouse gas emissions, and express this in terms of how dangerous they are in relation to carbon dioxide. This gives us “Carbon Dioxide Equivalent” (C02e) and is the gold-standard international IPCC benchmark for comparing emissions. This is the method we will use.

Jamais Cascio shows the way: “ The first step in answering this question requires figuring out the life cycle energy of a burger, and it turns out we're in luck. Energy Use in the Food Sector (PDF), a 2000 report from Stockholm University and the Swiss Federal Institute of Technology, does just that. This highly-detailed report covers the myriad elements going into the production of the components of a burger, from growing and milling the wheat to make bread, to feeding, slaughtering and freezing the cattle for meat -- even the energy costs of pickling cucumbers. The report is fascinating in its own right, but it also gives us exactly what we need to make a relatively decent estimation of the carbon footprint of a burger. Overall, the researchers conclude that the total energy use going into a single burger amounts to somewhere between about 7 and 20 megajoules (the range comes from the variety of methods available to the food industry)”

We need to split the carbon footprint into transportation and cooking/heating energy:

Diesel -- 4.7 to 10.8 MJ per burger
Electricity -- 2.6 to 8.4 MJ per burger

The carbon footprint also varies depending on the energy source required to cook the meat. Electricity from Natural Gas gives out less C02 than Coal. Putting in the results gives us a range:

Gas -- 416 to 1340 grams of carbon dioxide per burger
Coal -- 676 to 2200 grams of carbon dioxide per burger

Add transportation costs: diesel -- 350 to 800 grams of carbon dioxide per burger

Adding this up we reach a range of 766 grams of CO2 (at the low end, with gas) to 3000 grams of CO2 (at the high end, with coal). There's also carbon costs from running the burger bar, and travelling and from it. Let's say between 1 and 3 kilogrammes of C02 per burger.

However we have omitted an important source of green house gases : cow farts. Cattle produce methane, which is 23 times more damaging a greenhouse gas than carbon dioxide. We need to calculate this.

Jamais Cascio says: “so over its likely lifetime, a beef cow produces 220 kilos of methane. Since a single kilo of methane is the equivalent of 23 kilos of carbon dioxide, a single beef cow produces a bit more than 5,000 CO2-equivalent kilograms of methane over its life.” Meat producers expect to get 2000 burgers out of each cow, which works out at “2.6 CO2-equivalent kilograms of additional greenhouse gas emissions from methane.”

So we now have a total per burger: 3.6 – 5.6 kilogrammes of C02 equivalent (C02e) per burger. Let's split the difference and call it 4.5 kg/burger.

Back to the consumption: 50 per year.

60,000,000 UK citizens

50 burgers per year

= 300,000,000 burgers eaten.

Times 4.5 kg per burger

= 1,305,000,000,000 kg of C02e

divide by 1000 to get metric tonnes

13.5 million tonnes of C02e released by burger consumption annually in the UK. Or 200 kg per person per year. Or about one-seventh of what the average Briton emits through food, which is 1.39 tonnes.

Total UK emissions are about 600 m tonnes of C02e therefore burger consumption emits 2.16% of this total.

An average SUV emits 6 tonnes per year. Burger consumption is the equivalent of 2.25 million SUVs on our roads. There are actually around 200,000 SUVs in the UK so this is more than ten times the emissions. So burgers actually do make a significant contribution to our nation's carbon emissions.

The Cheeseburger footprint

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