Excerpt [from UK edition]
A few years ago I agreed to go round a supermarket with a journalist who wanted to write an article on low-carbon food. We trailed up and down the aisles with the dictaphone running and she plied me with questions, most of which I was pitifully unable to answer.
'What about these bananas?
How about this cheese?
It's organic. That must be better
Or is it?
Lettuce must be harmless, right?
Should we have come here by bus?
At least we didn't fly! How big a deal is food anyway?'
It was not at all clear what the carbon-conscious shopper should do. There was clearly a huge gap in the available consumer knowledge and on that day we couldn't fill it. The article never happened, and it's probably just as well. Since then, I have looked long and hard into all kinds of carbon footprints, and carried out numerous studies, including one for a supermarket chain.
This book is here to answer the journalist's questions, and many more besides. It's not just a book about food and travel. I want to give you a sense of the carbon impact - that is, the climate change impact - of everything you do and think about. I want to give you a carbon instinct. Although I have discussed the footprint of just under one hundred items, I hope by the time you have read about these you will have gained such a sense of where carbon impacts come from that you will be able to make a reasonable guesstimate of the footprint of more or less anything and everything that you come across. It won't be exact, but I hope you'll at least be able to get the number of zeros right most of the time. There are messages here for personal lives, for businesses and a few sprinkled in for policy makers too.
I'm not trying to give you a list of 500 things you can do to help save the planet. You could probably already write that list yourself. You will find at least 500 possibilities in here, but this is a book about helping you work out where you can get the best return for your effort. This book is here to help you pick your battles. If you enjoy the read and by the end of it have thought of a few things that can improve your life while cutting a decent chunk out of your carbon, then I'll be happy. The book isn't here to tell you what to do or how radical to be. Those are personal decisions.
CO2e? What's that?
Man-made climate change, also known as global warming, is caused by the release of certain types of gas into the atmosphere. The dominant man-made greenhouse gas is carbon dioxide (CO2), which is emitted whenever we burn fossil fuels in homes, factories or power stations. But other greenhouse gases are also important. Methane (CH4), for example, which is emitted mainly by agriculture and landfill sites, is 25 times more potent per kilogram than carbon dioxide. Even more potent but emitted in smaller quantities are nitrous oxide (N2O), which is about 300 times more potent than carbon dioxide and released mainly from industrial processes and farming, and refrigerant gases, which are typically several thousand times more potent than carbon dioxide. In the UK, the total impact on the climate breaks down like this: carbon dioxide (86 per cent), methane (7 per cent), nitrous oxide (6 per cent) and refrigerant gases (1 per cent). Given that a single item or activity can cause multiple different greenhouse gases to be emitted, each in different quantities, a carbon footprint if written out in full could get pretty confusing. To avoid this, the convention is to express a carbon footprint in terms of carbon dioxide equivalent (CO2e). This means the total climate change impact of all the greenhouse gases caused by an item or activity rolled into one and expressed in terms of the amount of carbon dioxide that would have the same impact.
A TEXT MESSAGE
0.014 g CO2e one message
32,000 tonnes CO2e all world's texts for a year
The biggest part of a text message's footprint is the power used by your phone while you type - and of course by your friend's phone while they read what you've written. If the two of you take a minute between you to type and read the message, and you each have phones that consume 1 watt of power when in use, the message's footprint will be about a hundredth of a gram. This figure takes into account the transmission of a 140-character message across the network.1
Around the world, about 2.5 trillion texts are sent every year.2 Don't be fooled into thinking that the 32,000 tonnes footprint for this total is a big number. It isn't. 32,000 tonnes is about one ten-thousandth of a per cent of the world's carbon footprint. In other words, texting is not a big deal. It wouldn't even be a big deal if my numbers were out by a factor of a hundred.
Incidentally, as of 2008, nearly a quarter of all text messages were sent in China, and about a fifth in the Philippines, where they average an impressive 15 messages per day for each phone. The average North American phone sent just a couple of messages a day, whereas British phones manage six texts per handset.
In summary, we can relax about sending texts (but no spam, please).
1 KG OF CARROTS
0.25 kg CO2e local, in season
0.3 kg CO2e average
1 kg CO2e shipped baby carrots
So a bag of carrots is like a 2-mile train ride.
At around 2 g CO2e per calorie, these and other root vegetables are some of the most climate-friendly foods available - and healthy too. If you ate only these foods and others that have similar carbon intensity you could feed yourself for just over 1 kg CO2e per day, or less than 500 kg CO2e per year.
Seasonal vegetables have small carbon footprints because they avoid all of the main greenhouse gas sources for food: they are grown in natural conditions without artificial heat, they don't go on aeroplanes, and they don't incur the inefficiencies inherent in the production of food from animals.
If you go on to boil your carrots for 10 minutes, you will add a few more grams CO2e per kilo to the footprint. (For more on cooking, see boiled potatoes, page 69.) My children will only eat their carrots raw. That suits me fine. It's better from every angle - there's less carbon emission, it saves time, and the nutritional value is better.
Note that some baby varieties have a much lower yield per acre of land, resulting in higher emissions per kilogram. So it usually makes sense to buy full-sized, classic varieties. And, as with other vegetables, favouring misshapen specimens may help avoid wastage in the supply chain (see page 183).