eBook - ePub
Food and Climate Change without the hot air
Change your diet: the easiest way to help save the planet
S L Bridle
This is a test
- 256 pages
- English
- ePUB (adapté aux mobiles)
- Disponible sur iOS et Android
eBook - ePub
Food and Climate Change without the hot air
Change your diet: the easiest way to help save the planet
S L Bridle
DĂ©tails du livre
Aperçu du livre
Table des matiĂšres
Citations
Ă propos de ce livre
"âą 25% of greenhouse gas emissions come from food â how can we reduce this?
âą What effect does the food we eat have on the environment?
âą How will climate change affect the food we will eat in the future?
âą Can the choices we make as consumers reduce carbon emissions dramatically?
Inspired by the author's former mentor David MacKay (Sustainable Energy without the Hot Air), Food and Climate Change is a rigorously researched discussion of how food and climate change are intimately connected. In this ground-breaking and accessible work, Prof Sarah Bridle focuses on facts rather than emotive descriptions. Highly illustrated in full colour throughout, the book explains how anyone can reduce the climate impact of their food."
Foire aux questions
Comment puis-je résilier mon abonnement ?
Il vous suffit de vous rendre dans la section compte dans paramĂštres et de cliquer sur « RĂ©silier lâabonnement ». Câest aussi simple que cela ! Une fois que vous aurez rĂ©siliĂ© votre abonnement, il restera actif pour le reste de la pĂ©riode pour laquelle vous avez payĂ©. DĂ©couvrez-en plus ici.
Puis-je / comment puis-je télécharger des livres ?
Pour le moment, tous nos livres en format ePub adaptĂ©s aux mobiles peuvent ĂȘtre tĂ©lĂ©chargĂ©s via lâapplication. La plupart de nos PDF sont Ă©galement disponibles en tĂ©lĂ©chargement et les autres seront tĂ©lĂ©chargeables trĂšs prochainement. DĂ©couvrez-en plus ici.
Quelle est la différence entre les formules tarifaires ?
Les deux abonnements vous donnent un accĂšs complet Ă la bibliothĂšque et Ă toutes les fonctionnalitĂ©s de Perlego. Les seules diffĂ©rences sont les tarifs ainsi que la pĂ©riode dâabonnement : avec lâabonnement annuel, vous Ă©conomiserez environ 30 % par rapport Ă 12 mois dâabonnement mensuel.
Quâest-ce que Perlego ?
Nous sommes un service dâabonnement Ă des ouvrages universitaires en ligne, oĂč vous pouvez accĂ©der Ă toute une bibliothĂšque pour un prix infĂ©rieur Ă celui dâun seul livre par mois. Avec plus dâun million de livres sur plus de 1 000 sujets, nous avons ce quâil vous faut ! DĂ©couvrez-en plus ici.
Prenez-vous en charge la synthÚse vocale ?
Recherchez le symbole Ăcouter sur votre prochain livre pour voir si vous pouvez lâĂ©couter. Lâoutil Ăcouter lit le texte Ă haute voix pour vous, en surlignant le passage qui est en cours de lecture. Vous pouvez le mettre sur pause, lâaccĂ©lĂ©rer ou le ralentir. DĂ©couvrez-en plus ici.
Est-ce que Food and Climate Change without the hot air est un PDF/ePUB en ligne ?
Oui, vous pouvez accĂ©der Ă Food and Climate Change without the hot air par S L Bridle en format PDF et/ou ePUB ainsi quâĂ dâautres livres populaires dans Ciencias biolĂłgicas et Ciencia medioambiental. Nous disposons de plus dâun million dâouvrages Ă dĂ©couvrir dans notre catalogue.
Informations
Sujet
Ciencias biolĂłgicasSous-sujet
Ciencia medioambiental1
Chapter 1 Introduction
How much do you think the last meal you ate contributed to climate change? And which bits of it were the biggest culprits? Diets aimed at reducing environmental impact are becoming more popular, for example vegans avoid all animal products including meat, fish, cheese, milk and eggs. But does this really help, and anyway how much of a big deal is food compared to all the other contributions to climate change?
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.
My efforts to help reduce climate change were based on little more than a gut feeling. What I really needed was detailed figures, so I could make informed decisions that would make a big difference, and thatâs why I wrote this book â to get clear numbers that I could use, and share with everyone else.
Climate change
The overwhelming scientific consensus is that climate change is real, it is happening, and it needs to be addressed. There is a wealth of information available about climate change, so this book doesnât repeat all that. There is just a short appendix at the end, summarizing the main facts (appendix âClimate changeâ).
However, we will address one issue that often confuses people: whatâs the difference between climate change and global warming? Yes, greenhouse gases in the Earthâs atmosphere are trapping heat and cause the planet to warm up. (Thereâs more detail on greenhouse gases in the next section.) However, some parts of the globe are warming up faster than others. For example the continents warm up faster than the oceans. 2However, the world isnât just getting warmer â the changing climate causes extreme weather events such as droughts, floods, and storms, sometimes affecting multiple continents (appendix âClimate changeâ).
So the âglobalâ in âglobal warmingâ refers to the temperature change averaged across the whole the surface of the Earth. While itâs nice to focus on a single number, this hides a complexity that has serious consequences. Cloud, wind and rainfall patterns have an intricate dependence on variations in temperature from one geographical location to another.
This changing climate also affects food production (appendix âImpacts of climate change on foodâ); some farmers have already had to change what they grow. Looking ahead, crop yields and the numbers of fish caught at sea are expected to go down.
âThe main way that most people will experience climate change is through the impact on food: the food they eat, the price they pay for it, and the availability and choice that they haveâ
â Tim Gore, Head of Policy, Advocacy and Research of Oxfamâs GROW Campaign
Greenhouse gases
We humans release a range of gases into the atmosphere. The most important of these that contribute to global warming are carbon dioxide, methane and nitrous oxide.1 The best known of these is carbon dioxide (CO2), which is released by burning fossil fuels â in cars, aeroplanes, heating and to generate electricity.
When plants rot in a damp place they turn into methane, which is how natural gas (which is a âfossil fuelâ) was made in the first place (appendix âClimate changeâ). In addition, about one twentieth of all the calories eaten by a cow are burped out again as methane (chapter 4). Because of the amount of food weâre producing to feed the world, and because weâre producing fossil fuels, the amount of methane in the atmosphere is increasing. When it first enters the atmosphere, 1 gram of methane causes more warming than 80 grams of carbon dioxide, but it only lasts for about 10 years before turning into carbon dioxide, so the total heat-trapping effect is equivalent to about 28 grams of carbon dioxide over a 100-year period. Have you ever inhaled laughing gas (another name for nitrous oxide)? I had nitrous oxide as a painkiller when I was giving birth â it made the pain seem less important, but I donât remember laughing! One gram of nitrous oxide causes a similar global warming effect to about 270 grams of carbon dioxide.
The amount of nitrous oxide in the atmosphere is increasing 3because weâre feeding our crops with nitrogen fertilizers (box 2.1), and because nitrous oxide is released from animal manure (chapter 4).
For the rest of this book we will talk about âgreenhouse-gas emissionsâ to refer to the combined effect of all the greenhouse gases. We will describe emissions in grams of carbon dioxide equivalent (written as âgCO2eâ in the scientific literature) which means the amount of carbon dioxide that would cause the same energy input as all the greenhouse gases combined together, averaged over a one hundred year period. Therefore
- 100 grams of carbon dioxide corresponds to 100 grams of greenhouse-gas emissions
- 4 grams of methane corresponds to 100 grams of greenhouse-gas emissions, and
- 0.4 grams of nitrous oxide corresponds to 100 grams of greenhouse-gas emissions.
Box 1.1: Grams, kilos and precise numbers
Throughout this book we will talk about the number of grams of food consumed, as well as the number of grams of emissions. This can be written out the long way e.g. â20 gramsâ or in a more compact way e.g. â20 gâ. When the numbers get big we sometimes switch to using kilograms (or âkilosâ, for short), where one kilogram (1 kg) is the same as 1000 grams (1000 g).
To make this book easier to use and more readable, it has to be specific about the amount of greenhouse-gas emissions from different types of food. To make it easier to use the numbers we have highlighted them throughout, like this:
1 g milk = 2 g emissions
However, the actual values will depend on the specific production systems used. For example, in the case of cowsâ milk it will depend on what the cow is eating and how much milk it produces. In the case of plants it will depend on the soil type (which affects the amount of fertilizer needed) and weather (which affects yield for a given amount of fertilizer).
So there is no single number, only a range of numbers for different suppliers. But we have to start somewhere. My hope is that you will start to demand the exact information from your food suppliers, so that you can make informed choices and buy from the producers who are making advances in reducing their impact on the climate. 4
How much emissions?
So where are all these greenhouse gases coming from? Fig. 1.1 shows a map of the world showing total greenhouse-gas emissions (not just food-related) for each country. On average, each world citizen causes about 24 kilos of emissions per day, but this varies greatly from one country (and person) to the next. For example, an average US citizen causes over 50 kilos of emissions per day, whereas an average citizen of most African countries causes less than 2 kilos of emission per day.
How much do you think food contributes to the total emissions? To work this out we need to add up all the greenhouse-gas emissions from all parts of the food chain. We have to include growing, clearing land, processing, manufacturing, packaging and transportation, as well as cooking the food at home and disposing of any waste. Overall, about a quarter of all global greenhouse-gas emissions come from food (Fig. 1.2). The amount of emissions from food varies from one country to the next, as does the total emissions. Food typically causes about a quarter to one third of the emissions.
The amount of emissions varies greatly depending on which food is being eaten, and on the production method. For example, a steak causes more than 10 times the emissions of a portion of beans. Furthermore, the steak itself can cause 10 times the emissions again if the cow lives for 20 years instead of just 1 year (chapter 24). Fig. 1.3 shows the amount of greenhouse-gas emissions for different food categories, for the amounts of each type of food consumed in the UK. In the rest of this book we 5consider the emissions from producing each of these foods, and investigate some alternatives. But first we need to get a sense of scale.
Box 1.2: Giga/billions tons/tonnes
When we discuss large amounts of CO2 we use metric tonnes. A metric tonne is 1,000 kg by definition, and an imperial ton is 1,016 kg, so you hardly ever have to worry about the difference â itâs less than 2%). One gigatonne (1 Gt) equals one billion tonnes (giga = billion, or one thousand million).
Food emissions in perspective
On average, each person in the world ...