Food and Climate change – Without the Hot Air

Sustainable Energy Without the Hot Air was published by David MacKay in 2009, and it remains a go-to resource for level headed facts about energy, not least because it’s available in its entirety online. The publisher, UIT Cambridge, have since produced a series of ‘without the hot air’ books in a similar vein, including books on materials and on urban transport that I’ve reviewed here before.

This latest in the series takes the same approach of crunching the numbers and presenting them in imaginative ways, with lots of illustrations. It reads slightly differently however. In fact, the contents page reads like a menu. Sarah Bridle’s book examines the climate impact of food, and it is approached one food at a time. The first chapter is called ‘breakfast’, the second is called ‘lunch’ and so on. Within each chapter, subsections look at specific foods: a bowl of cereal, a baked potato, a handful of nuts, or a beer cooling in the fridge.

Each food is discussed over a couple of pages, looking at the emissions involved in the various ingredients, and the methods of cooking it. Different variations are considered – for example, what emissions are added if you put jam on your buttered toast? What if you use an oil-based spread instead of butter? The information is then presented as a ‘stack’ showing how it breaks down. Here is the emissions profile of a toasted sandwich as an example.

The breakdown of foods is enlightening. With that toastie, it might be tempting to forego the toasting and have it as a sandwich to avoid the energy use of the toaster. But the bigger difference would be to leave out the cheese. And if you were to take out the ham and make it a steak sandwich instead, the emissions would triple.

There are some lessons in the book that you’ll have seen elsewhere, such as the vastly outsized emissions of beef, the relative difference that vegetarian or vegan diets can make, or the importance of reducing food waste. It also highlights the difference you can make with smaller swaps, such as making a bolognaise with chicken instead of beef, or the difference between a normal white coffee and a latte. One thing that is rarely pointed out is how much more efficient it is to cook for more people at once.

There is a level of geekery to this number slicing that could make the book abstract and overly calculated, but that’s not how it comes across. The author says at the outset that she has written “the book I’d have liked to read”, and I thought it had a real warmth and generosity about it. It doesn’t take itself too seriously (at one point Bridle points out that we could theoretically lower the emissions of cheese by making it with horse milk), and it’s written with curiosity and an appreciation for food. It felt very rooted in everyday choices, and most of all, it’s practical and useful.

Have a browse, and it is likely to inspire some changes of habits. Some might be major, some might be little tweaks and alternatives that will reduce your carbon footprint. Both kinds matter: a quarter of global emissions come from food, in the growing, processing, shipping and cooking of it. To make it to net zero, we’re all going to need a better understanding of the emissions in food, both at the systems level and in our personal choices.