Food and Climate Change Without The Hot Air: A Review

Friends, as you may recall I have reduced emissions from my home from about 3.7 tonnes per year to around 0.7 tonnes per year, and this should come down in future years as the electricity supply incorporates a greater fraction of renewable generation.

But my house is only one of the ways in which I emit carbon dioxide. And in the last year I have been working on reducing carbon dioxide emissions associated with my consumption of food. This is a much cheaper endeavour financially, but one which forces me to address habits I have ingrained over the my life. And that makes it hard emotionally.

My minor triumph in this area was giving up milk in tea and coffee (link). Throughout my life I have drunk prodigious quantities of tea and coffee with milk, and so this was initially a real sacrifice. But one year later, I have incorporated this into my lifestyle. And I have been working on reducing the residual meat and dairy in my diet, though rather less successfully.

In order to improve my understanding, last year I bought “Food and Climate Change without the hot air” (FACCWTHA) by Sarah Bridle and read it avidly. I had meant to write a review last year, but somehow despite the slow pace of my life in Teddington, I somehow could not find the time! But a couple of months ago I heard Professor Bridle speak and felt re-inspired.

Admirably (in my opinion), Professor Bridle began her career researching the physics of extra-galactic astronomy, but switched fields to help address climate change. Her research now focuses on using data to help transform food systems.


Friends, working out the carbon dioxide emissions associated with food is a colossally difficult problem. It has all the hallmarks of carbon accounting – which I hate!

Let me give you an example: when one goes to the supermarket to buy – say – a tomato, there is no fixed answer to the question: how much carbon dioxide emission is associated with each tomato. It depends on the time of year, the country of origin, how it was grown, how it was transported to the UK, how we will take it back home from the shop, and how it will be cooked. And the same is true for almost everything we eat.

And so FACCWTHA is not a database in which one can just look up a food stuff. Rather it is a narrative description of the factors which affect the emissions associated with our food choices. Consider it a book written to raise your own consciousness.

In the introduction Professor Bridle writes:

When I first learned about the impact of food on climate change I went vegan for a while. I put my jacket potato into the oven for two hours and waited around smugly with my can of beans, unpacking my suitcase after a transatlantic flight. I drove to the shop 3 km (1.86 miles) down the road just to buy some plant milk, and also probably picked up a pack of green beans flown in from another continent.

Following up on this paragraph, Professor Bridle then compares the emissions associated with her flight, ‘popping’ to the shops by car, and using an oven for two hours.

  • Flight: about 9 kg/day averaged over 1 year
  • Car: about 0.5 kg
  • Oven: about 2.5 kg

The emissions associated with the potato itself (about 0.3 kg) are almost negligible.

In the introduction Professor Bridle explains emissions associated with food amount to about a quarter of global emissions – equivalent to about 10 billion tonnes per year. If we divide that by the world population (around 8 billion), and by 365 we arrive at around 3 kg/day/person. But in wealthy countries, we often have associated emissions much higher than this. So Professor Bridle suggests we use around 3 kg/day as a target.

It might seem that there is no hope: that everything we eat is part of a web of actions and connections that can never be disentangled. And indeed, it is practically impossible to place a definitive amount of emissions on a specific purchase of a specific type of food. But there is hope!

In FACCWTHA Professor Bridle takes us on a tour through typical breakfasts, lunches and dinners and very quickly patterns emerge, and one begins to the learn the things which tend to have low associated emissions and things which tend to have high emissions.

For example, when she returns to analyse baked potatoes in Chapter 11 we are already familiar with the elements of a high emission meal. A single baked potato cooked in an oven and accompanied by ‘lashings’ of cheese could lead to more than 3 kg of emissions (a day’s worth or emissions) whereas the same baked potato cooked in a microwave with low-impact toppings might lead to only 0.3 kg of emissions.

(Cooking tip! Personally when I prepare baked potatoes I microwave them (typically four at a  time) for 15 minutes first before transferring them to a small oven to crisp up).

Click image for a larger version: Graphic illustrating the different emissions associated with a baked potato cooked in different ways and accompanied by different toppings.

As we go through the classic meals of the day, the themes emerge:

  • Food which has been flown to the UK has high associated emissions, but food which has been shipped to the UK can have surprisingly low emissions.
  • Plants of all kinds generally have low associated emissions arising mainly from cooking, transport and the use fertiliser.
  • Dairy products have higher emissions than vegetables and products such as cheese – that require large volumes of milk – can have very high associated emissions.
  • And meat products have high emissions, most especially beef and mutton because of the methane emissions associated with the animals processing of grass.

And although the book is not a database, it does handily summarise the carbon dioxide emissions associated with 1 gram of a variety of foods: I’ve compiled a list at the end of this article.

Most foods give rise to – very roughly – their own mass in  emissions. And since people typically eat between 1 kg and 2 kg of food per day, then it should be no problem to keep below 3 kgCO2 emissions per day.

However there are a few foodstuffs that have such high associated emissions, that in order to keep below 3 kgCO2/day, one would needs to restrict their consumption to being only – on average – a few grams per day.

In practical terms this corresponds to restricting consumption of these foodstuffs, making them rare ‘treats’ rather than regular staples. And these foodstuffs are, unsurprisingly, meat, cheese, greenhouse-grown vegetables, and farmed fish.

For example to restrict emissions to below 1 kgCO2/day on average one would need to eat less than 150 g of beef per week.

Click image for a larger version: Graphic illustrating the different emissions associated with three different evening dinner options.


Friends, FACCWTHA addresses an urgent issue. How do we reduce carbon dioxide emissions associated with what we eat? The book is engagingly written, well-researched with extensive references, and after reading it I found my consciousness had indeed raised, and it was now just up to me.

After reading the book I was reminded of Michael Pollen’s assertion that to eat well we should:

“Eat food. Not too much. Mostly plants”

And I understood that far from being mysterious, reducing carbon dioxide emissions from the food I eat is simple: but it requires that I re-balance my diet. This is hard because I am an old man and my habits are well set. But even at my advanced age, I can happily recommend this book, and suggest that you browse You Tube for inspiration for recipes. Personally, I have enjoyed the easy-vegan style of Will Yeung.

Carbon Intensity of foodstuffs

The table below is compiled from FACCWTHA and shows roughly the emissions associated with eating 1 gram of each of the foodstuffs listed.  The columns also show how much of that food can be eaten each day (and each week) to reduce that food item’s impact to 1 kg CO2/day on average.

Category 1 gram of … produces


kg to keep below 1 kgCO2/day kg to keep below 1 kgCO2/week
meat steak 46 0.02 0.152
meat lamb 43 0.02 0.163
drink instant coffee powder 17 0.06 0.412
dairy cheese 16 0.06 0.438
salad tomatoes, heated greenhouse 13 0.08 0.538
meat ham 11 0.09 0.636
sweets milk powder 9 0.11 0.778
meat chicken 9 0.11 0.778
dairy butter 8 0.13 0.875
transport anything 5000 km by air 8 0.13 0.875
fish salmon 8 0.13 0.875
packaging aluminium 6 0.17 1.17
egg egg 5 0.20 1.40
dairy cream 5 0.20 1.40
fish cod 5 0.20 1.40
snacks peanut butter 4 0.25 1.75
drink teabag 3 0.33 2.33
drink sugar 3 0.33 2.33
spread jam 3 0.33 2.33
grain cereal 3 0.33 2.33
spread relish 3 0.33 2.33
vegan Quorn slices 3 0.33 2.33
vegetables frozen oven chips 3 0.33 2.33
sweets cocoa 3 0.33 2.33
snacks peanuts 3 0.33 2.33
packaging plastic 3 0.33 2.33
packaging carboard landfilled 2 0.5 3.50
drink milk 2 0.5 3.50
salad sweetcorn 2 0.5 3.50
beans baked beans 2 0.5 3.50
packaging steel (for cans) 2 0.5 3.50
dairy yoghurt 2 0.5 3.50
fruit strawberries 2 0.5 3.50
fruit raspberries 2 0.5 3.50
snacks almonds 2 0.5 3.50
snacks crisps 2 0.5 3.50
drink orange juice 2 0.5 3.50
grain rice 2 0.5 3.50
beans beans (tinned) 1.8 0.6 3.89
spread vegetable spread 1.5 0.7 4.67
salad lettuce 1.5 0.7 4.67
vegan vegan cheese 1.4 0.7 5.00
packaging carboard composted 1 1.0 7.00
vegan Quorn pieces 1 1.0 7.00
spices spices 1 1.0 7.00
drink beer on tap 1 1.0 7.00
drink wine on tap 1 1.0 7.00
drink plant milk 0.8 1.3 8.75
grain flour 0.8 1.3 8.75
staple bread 0.8 1.3 8.75
packaging re-cycled plastic 0.8 1.3 8.75
vegetables french/green beans 0.8 1.3 8.75
fruit bananas 0.7 1.4 10.00
vegetables potato 0.6 1.7 11.67
beans beans 0.6 1.7 11.67
packaging glass 0.6 1.7 11.67
vegetables carrots 0.6 1.7 11.67
fruit apples (local in season) 0.4 2.5 17.50
vegetables cabbage 0.4 2.5 17.50
transport anything from NZ by ship 0.3 3.3 23.33
fruit oranges (local!) 0.3 3.3 23.33
snacks fizzy drink on tap 0.2 5.0 35.00
transport anything 400 km by truck 0.05 20.0 140.00
drink tap water 0.001 1000.0 7000.00

7 Responses to “Food and Climate Change Without The Hot Air: A Review”

  1. TheDuchess Says:

    Thank you for this review, I shall enjoy reading this book which I shall probably order from the library as part of my efforts to reduce my carbon footprint. One thing you haven’t mentioned is the benefits (in the U.K.) of carbon friendly farming practices. The methane produced by animals is partly offset by their role in maintaining carbon storing pasture for example.

    The most important thing is to accept that we have to adapt and change our behaviours. And then get on with it, making a few, bearable changes, then a few more. Repeat.

    In time you will prefer the change.

    • protonsforbreakfast Says:

      Good Morning. Thank you for your support. I didn’t discuss the nature of farming practices in the article because I was – like the book – just focussing on the ‘consumer’ end of the process.

      All the best: M

      • TheDuchess Says:

        I think it’s important to consider land use as part of the debate because all food production requires land. Unlike the fossil fuel debate where we can simply stop extracting, we cannot just change land use and assume there are no negative consequence.

        There’s a very interesting and thoughtful discussion about this topic on a BBC Sounds podcast

        Costing the Earth, “vegan World” first broadcast 26th November 2019

  2. David Cawkwell Says:

    Lidl do a nice spicy bean burger. I also blend up my own oat milk from oats so never run out of oat milk. Switching to oat milk wasn’t that hard just the same as switching from Full fat to semi skimmed milk. Going back to milk in tea and coffee seems far too rich. Birds custard powder is also vegan. I have switched to intermittent fasting for health benefits so skip breakfast and eat twice a day, now needing milk for cereal in the morning isn’t a problem I do miss the cereals though. I also I try and eat vegan or vegetarian for my midday meal.

    • protonsforbreakfast Says:

      David, They sound like pretty bold changes, so congratulations for that transition. I am still someway behind you!

      Best wishes: M

  3. Ian Nicholson Says:

    I have not being drinking anything other than black tea, I don’t have the money. Let’s call it povertea. I appreciate what you do but I don’t think you have any idea what constraints justify the poor.

    • protonsforbreakfast Says:

      Ian: I am sorry for the situation in which you find yourself. But like everyone living in the UK it is impossible to be unaware of the profound poverty all around us.

      And I am aware of the debilitating, disabling, depressing effect of grinding poverty. It’s shameful that it exists in our country. And through personal connections it is very real to me.

      Best wishes: Michael

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