Cars, cows and carbon

Cutting an American family’s meat consumption by half is equivalent to getting rid of a car. Why isn’t the pressure on, asks Tim Benton.

Tim Benton

The most recent figures for carbon dioxide levels in the atmosphere give one pause for thought. There was a bigger increase in CO2 in the atmosphere over the last year than had been recorded for many years; despite all we know, carbon is increasing faster than ever, and faster than imagined in IPCC’s ‘worst case’ scenarios.

In a meeting in late Spring, we were discussing what interventions could conceivably make a significant reduction in our personal carbon budgets that wouldn’t need a radical (and thus scary) lifestyle change. My thought was that by changing our consumption of meat we could have a surprisingly large impact.

‘Surprisingly’ because, although often discussed in foodie circles, it is not widely appreciated how much our meat consumption contributes to greenhouse-gas (GHG) emissions.

A top-down view of global emissions

Agriculture (including forestry and other land uses) is a very major component of our emissions. According to IPCC, global greenhouse gas emissions are 49Gt CO2e (i.e. methane and other greenhouse gases converted to equivalent units of CO2). Of these 14% are for the transport sector (that’s 6.86Gt), and 24% are for agriculture and forestry (and other land uses: so called AFOLU, so that’s 11.76Gt).

Deforestation for agriculture is a major source of GHG emissions.

Looking at the transport sector’s emissions, in the US, 42% is due to domestic cars (EPA fastfacts data sheet: 787/1834mt), in the UK its 52% (64/123mt: DECC figures) and in the EU it’s about 41% (670/1650mt, EU data).

Car ownership is higher in the EU and North America than many parts of the world, so it is likely that somewhere less than 50% of global transport will come from cars (i.e. <3.43Gt).  In contrast, livestock produce 7.1Gt of agriculture and forestry’s 11.76Gt. These figures are made up from methane from cow digestion (44%), land-use conversion to produce feed (27%) and 29% from cattle feed (grain, soya etc). Of this, about 4.6Gt CO2e is from cattle.

Thus, simply on a global basis, emissions from cattle probably exceed car emissions

Car for cow

Such a macro-analysis clearly has limitations. So, to get a feeling for this on a more personal basis, I looked up figures for the US – because I was asked to by someone who works in the US car industry.

USDA data, available online, shows that average American’s per capita annual meat consumption is 59lb beef, 48lb pork, 70lb chickens. A recent paper suggests that the CO2e emissions per kg of meat are 32.15kg for beef, 3.91kg for poultry and 5.91kg for pork. (Another recent paper provides a similar estimate for beef at 31kg CO2e per kg meat.)

My way or the highway: reducing meat consumption is roughly equivalent to taking a car off the road.

That suggests an average American’s meat consumption produces about 1.12 tonnes of carbon equivalents – the lion’s share of this is 862kg from beef.

Now let’s look at the data for domestic car use. According to US Federal Highway’s Agency, on average, each US car drives 12334 miles per year (19862km). A modern compact fuel efficient car is about 0.11kg CO2e per km.  A two-car family would therefore, on average, emit about 4.37 tonnes of carbon from driving their 24668 miles. If that two-car family had four people in it (imagine parents and two teenagers), their meat emissions would be essentially the same at 4.44 tonnes.

Driving change

Beef’s greenhouse gas footprint is very large (as Eshel’s paper highlights) because they are very inefficient at converting anything other than grass into meat. Increasingly, and especially in the US, demand for meat is leading to animals being fed concentrated food. On a global scale, enough calories to feed four billion humans is now being fed to livestock.

This concentrated diet turns beef cows into the resource-hungry SUVs of the livestock world.

Rearing cattle is an energy intensive and inefficient business.

But in many parts of the world, livestock production is nutritionally, economically, socially or environmentally important. In the UK, for example, much less concentrated food is used, so the GHG emissions per kilo of meat are typically lower than in the US. So while the analysis above may be taken as a vegetarian agenda this is too blunt a conclusion.

The point is that all our consumption (whether for food, water, cars or other goods) requires energy, and by changing patterns of consumption we can change emissions. For the US analysis, a family eating half the meat could make the same GHG saving as getting rid of a car, and this may have less of an impact on lifestyle and therefore be easier to achieve.

The person for the US car industry ended up shouting at me down the phone: “My industry has been under enormous pressure to reduce GHG emissions, and every driver knows about the need for efficiency. Why isn’t the same pressure being put on me to change my diet?”

Add your comment.

About Tim Benton

Tim Benton is GFS Champion and an interdisciplinary researcher working on issues around agriculture-environment interactions. Formerly, he was Research Dean in the Faculty of Biological Sciences, University of Leeds, and Chair of the Africa College Partnership, an interdisciplinary virtual research institute concerned with sustainable agriculture in sub-Saharan Africa. He has worked on the links between farming and biodiversity (and ecosystem services) for many years.

6 thoughts on “Cars, cows and carbon

  1. @Tim

    This is a very readable and useful comparison. Two points occur to me.

    1. The emission figures for meat products are mostly quoted in terms of kg meat (usually boneless meat) consumed. However, they do not take account of the additional emissions involved in getting that meat to the consumer (processing, transport, packaging, retail). While it is hard to quantify these additional emissions for the food system as a whole, let alone the meat element alone (Tara Garnett has some figures in this paper them would raise the emissions from meat consumption even more.

    2. No doubt aware of the importance for livelihoods of grass-based beef production in the UK, and particularly in the uplands, you suggest that the main culprit is grain-fed beef and that the “concentrated diet turns beef cows into the resource-hungry SUVs of the livestock world.” Unfortunately, the reported evidence on the relative climate friendliness of different beef production systems is much more mixed (see the comparisons of grain-fed (also called conventional) beef with pasture beef in the US in this paper by Roos et al). The feed emissions must be balanced against the additional enteric fermentation emissions due to cattle requiring longer to finish on grass. Indeed, suckler beef production seems to be the highest GHG emitter in their survey of LCA results.

    There can be many reasons why supporting grass-fed compared to grain-fed beef production is desirable, but lower GHG emissions per kg of meat produced may not be one of them.

  2. Thanks Alan.

    The figures Sanders and Webber is a very detailed LCA study which includes transport etc (which gives the same sort of estimate as the Eshel paper, from a much more macro perspective). But I agree with your overall point about where you draw the boundaries for the system analysis matters. For example, the carbon emissions for the cars doesn’t include getting the fuel to the gas stations, or an LCA on the cars – so things could be “better or worse” depending on some of the details. I think the overall point I wished to make is that whilst people worry about car efficiency and even buy cars because of it that dietary choices also matter to a similar-ish extent is not well appreciated. As other industrial sectors increasingly decarbonise, the relative size of agri-food emissions is likely to grow and therefore become more prominent.

    On your other point, I also agree that it is not straightforwards that grass fed is better. The devil is in the detail. A grass-fed animal can emit more gases in its life than one finished on concentrate. But if the concentrate comes from recently converted rainforest soy, the LCA of the grass-fed may still be lower due to the land-use conversion issues. One finished on concentrate that contains e.g. grains as a by-product of a distillery may, however, have a lower emissions. Again, the heterogeneity does matter and meat and meat-eating shouldn’t be demonised: in many places livestock is hugely important. It, however, does emit a lot!

  3. Tim,
    I am empathetic toward the need for food security and GHG emission reductions and will be interested to read what happens in the EU debate today / tomorrow.
    Globally, we need to produce, distribute and prepare food more efficiently, waste less from field to fork AND on the plate. The example you present about halving the US family meat consumption may need to be expanded to more radical measures, such as global population control, if gross food consumption continues increase uncontrollably.
    Kind regards,

  4. Remember that cattle utilise land that cannot be used for crops and eat grasses etc that humans cannot utilise. Just a wee thought.

  5. Please remember that the livestock industry is just that – a commercial undertaking. It is simplistic to continue to only talk about reducing meat consumption, can we please move on to a more joined-up proposition? It is not sensible to try and engage the auto industry with a comment “people should own fewer cars”, ditto livestock.

    I co-wrote a short article nearly 2 years ago comparing cows and cars, with a focus on the topic that your car industry colleague highlighted – industry and legislation efforts to make cars more efficient. What we tried to add to this conversation is the missing piece – how can we similarly make cows more efficient?

  6. Interesting blog, John. I agree with you in the sense that reducing meat consumption needs a combination of public will, industry willingness to change and perhaps regulatory help. The public will remains important though and people choosing to consume less meat is one route (just like buying smaller cars). Reducing emissions per animal, whilst important, can create negative indirect consequences (like more profit going into bigger herds, emitting in total more carbon) – which was what has happened with NZ dairy. Hence, whilst industry responses are important – as your article suggests – more efficient cows works only if the efficiency savings don’t translate into more cows!

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