100 grams to 1 kilo (2.2 pounds)
23 g CO2e black tea or coffee, boiling only what you need
55 g CO2e with milk, boiling only what you need
74 g CO2e average, with milk, boiling double the water you need
236 g CO2e a large cappuccino
343 g CO2e a large latte
So if you drink four mugs of tea with milk per day, boiling just what you need, that’s the same as a 60-mile drive per year in an average car. A single latte every day would be nearly 1 percent of the 10-ton lifestyle.
The shock here is the milk. If you take tea or coffee with milk, and you boil only the water you need, then the milk accounts for two-thirds of the total footprint (see Milk). The obvious way to slash the footprint of your tea is reduce the amount of milk, or simply to take it black (herbal tea, anyone?) (Figure 4.1). Although this will reduce your nutritional intake, you could easily replace the lost calories with something more carbon friendly such as a biscuit.
I have based my cappuccino and latte sums on the large kind that some of the coffee-house chains encourage you to quaff. These come in with a higher impact than four or five carefully made Americanos, filter coffees, or teas. They also mean you are drinking an extra cup of milk, perhaps without realizing it.
FIGURE 4.1: The footprint of one cup of tea or coffee with no sugar.
At my work we’ve suddenly decided that next week we’re all going to do without milk in our drinks. At worst it will taste horrible. At best we’ll change habits of a lifetime, resulting in decades of reduced hassle, lower carbon, slight cost savings, and possibly even fractionally improved health. It has to be worth trying.*
If you boil more water than you need (as most people do), you could easily add 20 g CO2e to your drink. Boiling more than you need wastes time, money, and carbon; if you haven’t yet developed perfect judgment, to avoid this you can simply measure the water into the kettle by using a mug.
Finally, think about your mugs. Buy sturdy ones; look after them and save hot water by only washing them up at the end of the day, rather than using a fresh mug for every cup.
15 g CO2e one of 20 passengers squeezed into a minibus in the suburbs of La Paz
150 g CO2e typical city bus passenger
The efficiency of a bus is just about proportional to the number of people it is carrying. It also depends on the amount of stopping and starting.
La Paz, Bolivia, is the place I think of where this principle is practiced to perfection provided you are prepared to set aside a bit of safety and comfort. Twelve-seater minibuses charge around town with 20 or more people crammed inside. You can get just about anywhere for one Boliviano—a few cents—and you are unlucky if you have to wait more than 5 minutes. Most people in the developed world would choose a luxury version of this for perhaps five times the price, but the principle is sound, and in Bolivia 10 years ago the “value proposition” met the market need perfectly.
All my numbers have factored in the fuel supply chains as well as the exhaust pipe emissions. I also include a component for the emissions entailed in manufacturing the vehicle, although for the bus this is a small consideration because they do so many miles before needing replacement.1
89 g CO2e reusable, line-dried, washed at 60°C (140°F) in a large load, passed on to a second child
145 g CO2e disposable
280 g CO2e reusable, tumble-dried and washed at 90°C (190°F)
> So that’s 550 kg (1,200 lbs.) per child for two and a half years in disposables, the equivalent of nearly two and a half thousand large cappuccinos.
Most parents will be relieved to hear that there is usually no carbon advantage to be had from reusable diapers. On average they come out slightly worse, at 570 kg (1,250 lbs.) per child compared with 550 kg (1,200 lbs.) for disposables. And if you wash them very hot and tumble-dry them, reusables can be the worst option of all. However, if you put your mind to it, you can make reusables the lowest-carbon option. To do this, pass them on from child to child (so that the emissions embedded in the cotton are spread out more), wash them at a lower temperature (60°C/140°F), hang them out to dry on the line, and wash them in large loads.
For a disposable diaper, most of the footprint comes from its production. But about 15 percent arises from the methane emitted as its contents rot down in landfill (contrary to the myth that if you wrap them up in a plastic bag they will never rot at all).
The study I’m basing my figures on assumed that the average child stays in diapers for about two and a half years and is changed just over four times a day.2 On this basis, in the U.K., diapers account for something like one two-thousandth of total greenhouse gas emissions—or more like half a percent for homes with babies.
What does all this mean for the carbon-conscious family? If you have two children and stick to non-tumble-dried reusables throughout, you might be able to save nearly half a ton CO2e. You will also cut out landfill. It’s a significant efficiency, but (here’s the catch) you need to know your own minds before you start out because if you give up, revert to disposables and trash the reusables, it could be the option with the highest footprint of all. But try to keep all of this in perspective: if you take just one family holiday by plane, you will undo the carbon savings of perfect diaper practice many times over.
When he was the U.K.’s climate change secretary, Ed Miliband recently drew on the same diaper study to defend his announcement that his own children wear disposables. He was roasted—somewhat unfairly I thought—by blogging eco-mums who claimed that the study was fatally flawed. Poor chap. At least he’d thought about it. The debate illustrates, yet again, that this kind of analysis is more murky and subjective than we might think.
150 g CO2e (or 600 g per kilo/270 g per pound) grown in season in your own country
1.8 kg CO2e (or 7.2 kg per kilo/3.3 kg per pound) grown out of season and flown in, or grown locally in a hothouse
> How have we got into the habit of buying tasteless out-of-season strawberries, which have a footprint more than 10 times the tastier seasonal version?
Although I’ve given just one number for local, seasonal strawberries, the precise footprint depends on such things as the soil, the use of fertilizer and the use of polytunnels.3 Some of these variables increase both the yield and the emissions per acre, so whether they result in more or less carbon per strawberry is not so simple to work out. Luckily, they are all so much better than the out-of-season version that a good enough rule of thumb is just to stick to those grown in your own country—unless your government subsidizes the heating of greenhouses (as is the case, for example, in the Netherlands). This kind of hot-housing is, broadly speaking, just as bad as air-freighting the fruit from hotter countries (see Flying, and Asparagus).
In short, then, the best advice is to wait until they are in season, then enjoy them twice as much. Or if you really can’t wait, buy frozen or tinned: these lie somewhere in the middle of the range, in carbon terms, along with those traveling “middle distances” by road and boat from warmer climes.
All the figures here have taken account of the 23 percent average wastage between the field and the checkout. A small amount of the footprint is the packaging and this is actually in a good cause if it enables more of the strawberries to find their way into our mouths. The footprint of the plastic will typically be lower than that of the wasted fruit.
150 g CO2e Intercity standard class
160 g CO2e London Underground
190 g CO2e light rail or tram
300 g CO2e Intercity first class
> An 18-mile intercity rail journey has the same footprint as a cheeseburger, whereas a mile and a half journey on light rail is equivalent to a cup of milk
Although trains can be a relatively green way to get around, the figures above show that the emissions of rail journeys are higher than you might think. All the numbers provided include the direct emissions and electricity consumption of the moving train itself but also attempt to take account of the embodied emissions from train manufacture, the upkeep of the rail network and the running of all the infrastructure.4
The amount of energy required to propel a train down a track depends mainly on just a few simple things:5
> How fast the train goes. The air resistance goes up with the square of the speed.
> How many stops there are. Each stop wastes energy—the exact amount being proportional to the square of the speed and the weight of the train. Some newer trains reduce this stoppage waste through “regenerative braking,” a similar technology to the one used in hybrid cars.
> Rolling resistance of the wheels on the track. This is lower for trains than for cars because metal wheels on metal tracks are more efficient than rubber tires on asphalt. The rolling resistance goes up proportionally with the weight of the train.
> The type of fuel used. Electricity beats diesel because although there are inefficiencies in generating it from fossil fuels in the first place, once this has been done the train engine can turn almost all of the power into movement. A diesel engine is much less efficient.
Long-distance Intercity trains go fast (that’s bad) but stop infrequently (that’s good). In the U.K., they’re often electric (that’s good), but they’re also extremely heavy (that’s bad). The weight of the train per passenger seat, amazingly, is around twice that of an average car. Just to be clear, what I am saying is that the weight of a full train is twice that of all the cars that would be needed if each passenger drove instead. Professor Roger Kemp,6 who has looked at this astonishing fact in detail, explains it in terms of over-engineered safety: trains weigh at least twice what they need to because we have become obsessed with safety and have forgotten that rail travel is already over 100 times safer than driving. A couple of miles from my house an Intercity train derailed and rolled down a high embankment. Incredibly, only one person was killed. The event was still splashed across the national news, raising public fears, even though so many more people die on the roads every single day. One price of this excessive focus on safety may well be that twice as much energy is required to get our trains moving every time they leave a station.
First-class travel deserves a mention because the number of seats you can squeeze into a first-class carriage is around half the number in a standard-class carriage. This means that the weight being moved per person is doubled again; we’re now up to the weight of four cars per seat. I sometimes board trains where half the length is nearly empty first class and the rest is crowded standard class, suggesting that the real weight being hauled per first-class passenger may be even higher.
Things are a bit more complex when it comes to the Eurostar, because when it’s in France it runs on electricity that comes predominantly from nuclear power. This is low-carbon energy, whether or not you think nuclear power is worth it in other ways. However, I don’t think it is useful to think of trains in nuclear-friendly France as having a smaller footprint than those elsewhere—which is how they are sometimes portrayed. That’s because all the nuclear electricity that French power stations can produce would get used up regardless of whether any trains were running. In that sense, the trains are effectively powered by the fossil fuel plants that provide the extra electricity over and above the nuclear “baseload” (see A unit of electricity, for more on this somewhat confusing concept of marginal depend).
Interestingly, the London Underground is almost as low-carbon, per passenger mile, as Intercity trains, despite stopping much more often. This is mainly because people are packed in so tightly—almost tessellating, nose to armpit. Other reasons are that the Tube travels relatively slowly, is all-electric, and has lighter trains.
Overall, trains are generally a lot greener than cars but not as good as walking, cycling, or staying at home. A sensibly designed car can win, provided you fill it with people. Even two people traveling together are better off driving an efficient car than traveling first class. (See also New York City to Niagara Falls return.)
A 500 mL (16 oz.) bottle of water
110 g CO2e locally sourced and using local distribution
160 g CO2e average
215 g CO2e traveling 600 miles by road
> A bottle a day would add up to 0.6 percent of the 10-ton lifestyle.
Bottled water is more than 1,000 times more carbon intensive than its tap alternative, so knocking it out of our lives has got to be a simple win. It doesn’t even taste better.
Processing the water is the easy part: the bulk of the emissions come from packaging and transport. There is 80 g CO2e per quart just for the plastic. On top of that is the energy required to melt the PET (polyethylene terephthalate) balls down and mold them into bottles. Transport is significant because water is so heavy. If it has gone 600 miles by road, that could add a further 115 g CO2e per bottle.7 Shipping from Europe to North America is clearly not good news.
The small town of Bundanoon in Australia is world leader in the fight against the stuff with a ban of bottled water already in place. Concord in Massachusetts has announced plans to go bottled water free from January 2011, despite threats from the bottled water industry to sue. Meanwhile London has announced plans to start reintroducing public drinking fountains. All these are encouraging steps forward. If everyone switches away from bottles, it will be great for the environment and still just as healthy, refreshing, and convenient. Interestingly, even though people will be financially better off, the economy may look as though it has slowed down a fraction. This is a nice illustration of how inadequate it is to measure how we are doing by our economic growth. When we are all using the fountains, we might collectively look a shade poorer on paper because the few people who make their living persuading us to buy the bottled stuff will need new jobs. But that will be more than compensated for by the extra cash that the average person will save. So the economy will recede as we all get better off. Let’s not cry for the peddlers of bottled water either. Even if you don’t believe that they had it coming to them, they are clearly talented and persuasive people who are also more than capable of being successful in constructive careers.
If the world consumes 53 billion gallons of this bottled water per year,8 that’s 80 million tons of greenhouse gases, or one-sixth of a percent of global emissions. This is a win worth having!
140 g CO2e a 10 g letter made from recycled paper and recycled by you
200 g CO2e a typical 25 g letter printed on virgin paper and sent to landfill
1,600 g (3.5 lbs.) CO2e a small catalogue sent to landfill
> If you have five letters delivered per day plus two catalogues per week, that’s a massive 480 kg (1,060 lbs.) CO2e per year, nearly 5 percent of the 10-ton lifestyle.
Mail clocks up a carbon footprint in four basic ways (Figure 4.2):
> Paper production. The carbon footprint of paper manufacture depends on the recycled content, the quality of the paper and the efficiency of the mill. The junk mail coming through our door generally uses high-quality stuff and doesn’t tend to boast any recycled credentials. My estimates are based on paper that has a less than one-fifth recycled content. That gives it a footprint of 2.35 kg CO2e per kilo (1.07 kg CO2e per pound). The best estimate for pure virgin paper comes in at 2.59 kg per kilo (1.18 kg CO2e per pound), and 100 percent recycled paper at about half of that; it takes about half as much energy to create new paper from old paper as it does to create paper from trees.9
> Printing. For the footprint of printing on the paper to turn it into glossy and enticing sales literature, I estimate an additional 350 g CO2e per kilo (160 g per pound).
> Postage. For a standard letter, this accounts for most of the footprint. It’s impossibly difficult to trace the carbon footprint of mailing a letter by direct means. However, if you take the footprint of the postal services sector as a whole and divide it by the turnover of that sector, you can get a broad idea of the carbon footprint per unit of cost. In the U.K. it comes out at about 380 g CO2e per £1 spent (250 g per US$1). A 25 g regular mail letter would have cost 32p (48 cents) in the U.K., and we can associate a carbon footprint of about 120 g CO2e with that. So most of the impact of a junk letter comes from the burden that it places on the whole infrastructure of the postal system: vans, trains, and sorting offices.
> Decomposition. A good deal of junk mail ends up in landfill, where it decomposes anaerobically and produces methane. For this I have allowed 550 g CO2e per kilo (250 g per pound) of paper.10 You can prevent this, of course, by recycling as much mail as possible. This is OK to do even if the letter has a plastic window. But do remove any other plastic—such as film wrap.
FIGURE 4.2: The carbon footprint of a 25 g letter, printed on virgin paper, sent by mail, and thrown into landfill (grams CO2e).
Eliminating junk mail will declutter your life as well as save carbon. The purpose of most of it is to persuade you to buy stuff you don’t need, so brain purification is probably the biggest reason of all for putting an end to it. Shelly Shumacher writes in ehow.com11 that Americans receive an average of 41 pounds of junk mail per year and 44 percent of this ends up in landfill, and she also offers advice on how to get the stuff out of your life.12
Finally, a message to the instigators of junk mail: more and more people will think badly of you for using high-carbon marketing techniques. If you must use mailouts, at least keep your databases clean, use recycled paper, and keep your messages short.
Sending an email beats sending a letter hands down (see An email).
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 airplanes, 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 pound to the footprint. (For more on cooking, see Boiled potatoes.) 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 pound. So it usually makes sense to buy full-sized, classic varieties. And, as with other vegetables, favoring misshapen specimens may help prevent wastage in the supply chain (see Low-carbon food tips).
0.3 kg (0.66 lbs.) CO2e the U.K.’s Guardian Weekly, recycled
0.40 kg (0.77 lbs.) CO2e Globe & Mail Saturday edition, recycled
0.41 kg (0.91 lbs.) CO2e New York Times weekday edition, recycled
0.43 kg (0.94 lbs.) CO2e Globe & Mail weekday edition, recycled
0.8 kg (1.8 lbs.)CO2e the U.K.’s Guardian Daily, recycled
1.5 kg (3.3 lbs.) CO2e New York Times Sunday edition, recycled
3.2 kg (7.1 lbs.) CO2e New York Times Sunday edition, chucked into landfill
4.1 kg (9 lbs.) CO2e a typical British weekend broadsheet paper, sent to landfill
> I estimate that the New York Times every day, including Sundays, adds up to 207 kg (455 lbs.) CO2e per year, if you recycle them all, or 447 kg (984 lbs.) CO2e, if you chuck them in a garbage bin and off to landfill. The latter is equivalent to flying from New York to Atlanta and back or from San Francisco to Vancouver.
It’s amazing how energy-hungry newspaper production can be. And the figures provided here are on the low side, because none of them take account of the footprint of journalism itself—including the newspaper offices and staff flights. At the highest end of the spectrum, just the New York Times on Sunday each week could add up to almost 2 percent of a 10-ton lifestyle if you don’t recycle it (Figure 4.3). At 1.25 kg (2.8 lbs.), the weight of a U.K. weekend broadsheet is part of the problem. In our house only a tiny fraction would be read, so the rest might as well never have been printed.
The reasons why recycling is so important are twofold. First, if paper is disposed of in landfill sites, it emits methane as it rots. Second, for each newspaper that isn’t recycled, one more newspaper’s worth of virgin paper has to be manufactured. For these reasons, throwing your paper in the general waste more than doubles its footprint.13
FIGURE 4.3: The carbon footprint of a weekend newspaper. Sending paper to landfills causes methane emissions and means that more carbon-intensive virgin paper has to be produced.
Opting for a slimmed-down weekly paper is one good way to reduce both emissions and clutter. We take the U.K.’s Guardian Weekly, weighing just 300 g—condensed and interesting, if a few days out of date. Another way is to get your news online. If you do this for an hour a week on a 50-watt laptop and if we multiply that by, say, five to take account of the production of the laptop, the running of your network, and the electricity consumed by all the hubs and servers around the world that support the websites you browse, it still comes to around half the impact of the Guardian Weekly. If only I could take my laptop into the bath...
300 g CO2e locally brewed cask ale at the pub
500 g CO2e local bottled beer from the store or a pint of imported beer in a pub
900 g CO2e bottled beer from the store, extensively transported
> A pint of local ale per day in the pub would be 1 percent of the 10-ton lifestyle. A few bottles of imported lager per day might be as much as 10 percent.
The good news is that North America’s robust microbrewery industry gives many people plenty of tasty lower-carbon options.
The beer at the low end of the scale is based on figures for the Keswick Brewing Company, a microbrewery quite near where I live. Just about everything you can think of was included in the study I did for them (Figure 4.4). There were the obvious things such as ingredients, packaging, fuel, electricity, and transport. I also included such elements as staff travel, the carbon cost of having to replace their equipment every so many years, and office stationery.
FIGURE 4.4: The footprint of cask beer from the Keswick Brewing Company.
For the Keswick Brewing Company, I estimated that ingredients accounted for about one-third of the footprint, fuel and electricity about another one-quarter, and staff travel about one-tenth. The fermentation process itself releases CO2, accounting for about 15 g per pint, but these don’t count, since that carbon was absorbed by the ingredients as they grew. Most of the company’s beer is sold in reusable casks, so the footprint of packaging is kept right down. Distribution is 7 percent, even though all their deliveries are fairly local, because beer is such heavy stuff.
A few miles from the Keswick Brewery is another, larger brewery. Delivery from there to pubs just down the road is via a distribution center in Wolverhampton, a couple of hundred miles away. This is the usual story for big breweries and their subsidiaries. Even the country of origin is not always obvious from the branding. Although a few hundred road miles are not usually the most significant factor for foods, beer is an exception because it’s so heavy. Hence opting for local ale is usually a good idea.
For home consumption, and thinking for a moment only of carbon rather than taste, cans are slightly better than bottles, provided you recycle them. (I can feel the connoisseurs at Keswick cringing as I write.) Heeding this advice is especially important if the beer is traveling a long way because the glass also adds to the weight.
Wherever and whatever you drink, a single pint of a quality beer is almost always better for both you and the world than spending the same money on several tins of bargain-basement brew.
Finally, as though it were needed, the carbon angle gives yet another reason not to drink and drive (see Car crash).
82 g CO2e traditional Scottish, made with oats and water only
300 g CO2e about half milk (just how I like it)
550 g CO2e milky and sweet
> So a bowl of traditional Scottish porridge is equivalent to a 90-second cell-to-cell phone call.
A bowl of half-milk porridge every day would be about 1 percent of the 10-ton lifestyle. Cement and porridge made like this don’t just look the same; they also have very similar carbon intensity per kilo.
Oats, like most cereals, is a fantastic low-carbon food that also happens to be healthy and tasty. If you fed yourself entirely on milky sweet porridge, it would cause just 900 kg CO2e per year. By sticking to the Scottish water-based version, you’d cause a trifling 340 kg CO2e per year—about one-tenth of the typical U.K. diet. As with a cup of tea (see A mug of tea or coffee), it’s the milk that dominates.
The cooking is about half of the footprint of the traditional Scottish version. I’ve assumed that you cook it on the stove and never have the lid on because you are stirring like crazy, trying to save yourself a nightmare of cleanup. A nonstick pan should help. Better still, the microwave is lower carbon than an electric burner or gas ring and doesn’t cause sticking; but keep a close watch or it will turn into an exploding mess from Doctor Who. Enough said about all this. I am the last person who should be writing a cookery book.
A bowl of cold breakfast cereal or granola prevents the cleanup nightmare and offers similarly excellent carbon per calorie to a bowl of porridge with just a bit of milk.
90 g CO2e 3 minutes, efficient gas furnace, aerated showerhead
550 g CO2e 6 minutes in a typical electrically powered shower
1.9 kg (4 lbs.) CO2e 15 minutes in an 11-kilowatt, high-volume, electrically powered shower
> If you have high-carbon shower habits, there could be half a ton per year to be saved here—equivalent to a return flight from San Francisco to Vancouver, Chicago to Dallas, or New York to Atlanta.
At the low end of the spectrum, 3 minutes is how long I take if I wake up half an hour before my train is due to leave. Gas is a more efficient way of providing heat than electricity, provided you have a reasonably efficient furnace. The aerated shower head helps by making less water feel like more. In theory at least, it saves water and carbon without your having to forgo any comfort at all.
If you are in a family of four and you each spend 15 minutes in an electric shower every day, you may be able to reduce your household footprint by a ton per year just by switching to an aerated showerhead. Switch to a gas-powered shower, and there’s another half ton to be saved. Finally, you can cut the remaining emissions by a factor of three by having 5-minute showers—and it is only at this point that you are having any impact on your lifestyle. You will be swapping time in the shower for time doing almost anything else that you want: reading a book, lying in bed, both of these at once, or whatever you like. If you take all these measures, your family could knock off 2 tons per year—and save about $500, which would easily pay for the couple of paperbacks you might each luxuriously read in bed during the time you have liberated.14
The showers in Iceland are worth a mention as the most luxurious I’ve ever had. Geothermally heated and almost zero CO2e, they are all the more enjoyable after a day out in the abundant rain and snow there. Unfortunately you have to fly to get there. (See also Bath.)
50 g CO2e a 60 g Popsicle from the supermarket, eaten on the day of purchase
500 g CO2e a big dairy ice cream from a van
The Popsicle is essentially frozen sugary water, and in the supermarket the refrigeration is likely to be relatively efficient.
At the high-carbon end the dairy ice cream’s footprint is higher for three reasons: it’s bigger, it’s dairy based, and it’s been kept cold in a much less efficient mobile refrigeration unit. The inclusion of dairy ingredients means that all the inefficiency of ruminant livestock farming has been incurred. My figures are just based on cigarette-packet calculations. I’ve guesstimated from a broad understanding of the footprint of different food ingredients and transport impacts and from knowing a little bit about mobile refrigeration.
50 g CO2e using a solar water-heating panel
244 g CO2e using a modern (90 percent efficient) gas furnace
400 g CO2e using an old, 55 percent efficient gas furnace
660 g (1.45 lbs.) CO2e from U.S. grid electricity
1,060 g (2.34 lbs.) CO2e from Australian grid electricity
> By a “unit” I mean 1 kilowatt-hour. That is enough to run a “one-bar” electric fire for 1 hour or enough to boil about 4 gallons of water in an electric kettle.
At the low end, the solar water-heating panel has no operational emissions. I haven’t given it a zero CO2e rating because the manufacture of the panel itself will have a carbon footprint. The exact number depends on factors such as the design of the device, where it is used, and how it is maintained, so my figure is really just a guesstimate. One problem with solar heating is that it tends to be “low-grade” heat. In other words it’s all right for warming up baths and gently heating rooms but not usually much good for boiling kettles or making toast.
In the middle of my scale is heat generated by an efficient gas-fired furnace, such as might power a new central heating system. In this scenario your heating is done by fossil fuels, but at least you’re using them fairly efficiently: the only losses will typically be around 10 percent, as the energy disappears out of the flue.15
(That said, in the case of a central heating system there may also be inefficiencies caused by heating rooms that you are not actually using. If the only room you want to heat up is the kitchen, the most efficient thing you can do may be to turn on the gas stove. That way nothing goes up the flue, and all the heat goes into the room you want to keep warm.)
At the high end of the scale is electricity. This is a “high-grade” form of energy that can be used for many different things, so it’s generally a waste to use it just for heating. The precise footprint depends on which country you are in (see A country), but with only a few exceptions the figure will always be high because the electricity is usually generated from fossil fuels and—unlike with a gas furnace in your home—more than half the energy in the fuels is lost in the power station or transmission grid. In other words, it’s generally inefficient to use electricity just for heating. In the U.K., the average unit has a footprint of about 600 g (1.3 lbs.) CO2e,16 whereas the figure is higher, for example, in coal-dependent Australia.
60 g CO2e from the Icelandic grid
220 g CO2e from the Canadian grid
600 g (1.3 lbs.) CO2e from the U.K. grid
660 g (1.45 lbs.) CO2e from the U.S. grid
900 g (1.98 lbs.) CO2e from the Chinese grid
1,060 g (2.34 lbs.) CO2e from the Australian grid
> The carbon impact of using an additional unit of electricity is often higher than we’re LED to believe.
Electricity generation is one of the principal causes of carbon emissions all over the world. However, as we’ve seen, the exact carbon cost of each unit of power depends on the precise mix of generating fuels used in your country. Icelandic electricity comes almost exclusively from fossil fuel–free geothermal and hydropower plants, so the only footprint comes from creating and maintaining the infrastructure.
Australian and Chinese electricity, by contrast, comes mainly from highly polluting coal. U.S. and U.K. electricity is somewhere in the middle, coming from a mixture of coal, gas (which is less polluting than coal but is still a fossil fuel), nuclear (which has a low carbon footprint but is contentious in other ways), and a smattering of renewables. The mix is significantly cleaner in Canada but varies hugely between provinces.17
Most people who think about carbon footprints are used to the idea that each unit we consume causes a fixed quantity of CO2 emissions. However, the truth is somewhat more complex than that. A more meaningful way to think about the carbon footprint of your own electricity use is to think of it as being additional to all the power consumption that was already going on before you flicked on the light or appliance. Looked at this way, the extra demand that you place on the grid is met entirely through additional fossil fuels, because the renewables in your country will already be running at full capacity. In other words, when you turn the lights on, you don’t personally affect the amount generated by renewables because they are already going flat out. Rather, what you trigger is almost certain to be a lump of coal thrown into a power station. This is the case throughout Europe, because even in countries where all electricity comes from renewables or nuclear, adding to demand reduces the amount of electricity that those countries are able to export, thereby increasing the fossil fuel generation in other nations. In terms of “marginal demand” (see Table 4.1)—each unit of electricity you consume has a footprint of at least 1 kg (2.2 lbs.) CO2e per unit, regardless of which country you live in.
* (including the carbon cost of extracting fuel from the ground, maintaining and building power stations, wind turbines, etc.)
** e.g. the carbon cost or savings of each unit of electricity you choose to use or save
TABLE 4.1: The carbon footprint of electricity consumption in different countries. The marginal demand column shows that, unless you live in Iceland, someone somewhere is likely to have to burn more coal if you use more electricity.
One exception is Iceland, where, for the moment at least, it does look as though you can more or less use as much electricity as you like without boosting your footprint. The country is overflowing with hydroelectric and geothermal power: you can see the energy almost everywhere you go, boiling out of the mud and pouring over waterfalls. But once Iceland works out how to export its clean energy, or how to import enough of the world’s heavy industry to use up the renewables capacity, electricity will become a scarce resource for Icelanders, just as it is for the rest of us. In the meantime, enjoy it!
The great green tariff swindle?
“Green” or “renewable” electricity tariffs and suppliers may sound attractive, but the hard reality is that signing up is unlikely to reduce the climate change impact of your electricity significantly. This applies whatever the color of the company’s logo or however ecological the company name might sound.18
The two main claims made by the “green” providers are that electricity comes from renewable sources and/or that they use the money you spend on your bills to invest in a new renewable capacity. Neither of these is necessarily what it might appear.
The “from renewable sources” claim
All electricity suppliers in the U.K. are obliged to submit Renewable Obligation Certificates (ROCs) to the government for up to 10.4 percent of the electricity they sell to their customers. They can get these certificates either from generating their own renewable power or by buying them from others. Suppose a company has a tariff in which all electricity is sourced from renewables. It sounds great. However, this means that the supplier gets a lot more ROCs than they need to hand over to the government. The normal practice is for the “green supplier” to sell these to other suppliers, thereby allowing them to simply source less of their own power from renewables. So the net carbon benefit is zero—but the “green supplier” stands to benefit because it has managed to charge you a premium. The tariff only makes a difference to the extent that the provider retires some ROCs (tears them up) instead of selling them on. In the U.K., energy supplier Good Energy claims to do this with 5 percent of them, although this has been challenged, with some people suggesting they have been retiring only 2 or 3 percent. It doesn’t much matter, because they are arguing over such low percentages. The main point is that well over 90 percent of the ROCs are kept in circulation. If you switch to the “green tariff” offered by one of the larger electricity suppliers, the chances are that no ROCs are retired at all, and you are allowing them to worsen the energy mix in their other tariffs, while using the “green” story line as a way of charging you more.
The “investing in renewables” claim
What if a company claims that it will invest so much of every dollar you spend via the company in new wind farms and other renewable energy projects? This sounds great, but what it could boil down to is that the supplier is simply engaging in two different business activities. One is being an electricity provider just like all the others, but with “green” branding. The other part of the enterprise is investing in renewable power generation. Both of these could potentially be good business opportunities regardless of any environmental considerations. The key question is whether the investments in the new wind farms would still be made if you got your electricity from elsewhere. Is the company promising to invest to the tune of your electricity expense in projects that would otherwise not go ahead at all? In other words, is it genuinely additional? This is a very long way from being clear to me. One thing that is certain is that it is possible to run a roaring commercial enterprise along these lines.
I am not saying that the companies claiming to provide greener electricity aren’t greener than average. They probably are, and I do get my own electricity from one of them. What I am saying is that their impact may not be quite as low as you think. The overall message is that if you want to reduce the footprint of the electricity you buy via the grid, the only real way to do it is to consume less.
Minus 220 kg (485 lbs.) CO2e on a well-executed rainforest preservation project
Minus 2 kg (4.4 lbs.) CO2e on solar panels
105 g CO2e on financial, legal, or professional advice
480 g CO2e on a car
620 g (1.37 lbs.) CO2e on a typical supermarket cart of food19
3.1 kg (6.83 lbs.) CO2e on flights20
6.5 kg (14.3 lbs.) CO2e on gasoline
4 kg (8.8 lbs.) CO2e on the electricity bill
10 kg (22 lbs.) CO2e and beyond on budget flights
Unless you are deliberately investing in something that reduces emissions elsewhere, it is just about impossible to spend money without increasing your carbon footprint. Everything causes ripples of economic activity and, with it, emissions. So with wealth comes carbon responsibility. I’m hardly the first person to have suggested this, but it’s an important concept. So what are you going to do with your $1?
If all your money goes into travel, you may be at the worst end of the irresponsibly wealthy. If you invest it in forests and wind farms, you are at the opposite extreme, using your wealth to bring about a low-carbon world. If you spend a million dollars on fine art, you are mainly passing on the responsibility for doing the right thing with that cash to the artist or the dealer. If you stick it under the mattress, it is doing neither harm nor good.
Of the specific examples given above, flying gets to be such a high-impact way of spending cash for two reasons. First, the aviation industry can buy its fuel for around 50 cents per liter ($1.89 per gallon). Second, it then burns it at an altitude where it has, as a best estimate, nearly twice the climate change impact that it would have had at ground level. Leaving the lights on is another of the cheapest ways of trashing the planet, suggesting that for all the talk of higher fuel prices, we are a long way from establishing a serious financial incentive to go green.
My gasoline figure is based on $2.70 per gallon. My sums take account of the extraction, shipping, and refining of the fuel but not the depreciation or maintenance of the car.21
At the positive end, I have included some of the fairly limited options for actually doing carbon-friendly things with money. They range enormously in their effectiveness, which is something not all policy makers seem to have fully grasped.
In our input–output model, we’ve looked at the carbon intensity of industries from agriculture to manufacturing to education and social services. No industry sector in our model comes in below 100 g per U.S. dollar. The more you think about this, the clearer it becomes that there is simply no avoiding the advantages of slowing the economy down or of changing its structure. We could do with spending less time charging around earning as much as we can to buy things we don’t really need. We would do well to become better at enjoying what we’ve got—and to disentangle our self-esteems from our wages. Without wishing to sound like a sandal-wearer, I think it’s clear that we’ve become locked into a mindset that is not going to serve us well over the coming decades. If you’re not convinced, have a read of Tim Jackson’s book Prosperity without Growth.22
200 g CO2e garden waste
700 g (1.54 lbs.) CO2e average trash contents
9 kg (19.8 lbs.) CO2e aluminum and copper
The average U.S. citizen sends 570 kg (1,250 lbs.) to landfill or incineration23 each year and recycles just 290 kg (640 lbs.). This causes around 400 kg (880 lbs.) CO2e, or 4 percent of a 10-ton lifestyle.24
FIGURE 4.5: The annual footprint of the average U.K. homeowner sending waste to landfill rather than to recycling or composting.25
By “trash” I mean things you dispose of by putting them in the normal garbage as opposed to recycling or composting them. Looked at this way, the footprint has two parts.
First, there are the landfill emissions, which are due mainly to stuff rotting down underground, without air. This anaerobic decomposition produces methane, only some of which gets captured, and the rest escapes to warm the world. (This isn’t an issue for metals, glass, and building materials, of course, because they don’t rot down in the way that food, paper, and garden waste do.) There is also a little bit of fossil fuel required to run a landfill site.
Second, there is the fact that by not recycling something, you are forcing more virgin materials to be produced for use in future products. This isn’t an issue for food, for which recycling was never an option. But for metals, textiles, plastics, and paper it is a big deal.
FIGURE 4.6: The footprint per kilo (2.2 pounds) of throwing stuff into landfill compared with recycling or composting it. In other words, this graph shows the difference that recycling makes.
Figure 4.5 shows that recycling our aluminum and plastic is where most of us can make the biggest improvements. That’s mainly because it takes so much more energy to make a brand-new aluminum can or plastic bottle than it does to make a new one from an old one. Kitchen waste is a key area, too, because of the large amount of methane it produces when it rots underground.
Figure 4.6 shows that when you are standing with 1 kg (2.2 lbs.) of something in your hand, if that something is aluminum, it is particularly important that you recycle it. The next most important per kilo are textiles.
The significance of food waste is underplayed in both these graphs because they don’t take account of the footprint of needless production. These graphs just show the difference between landfill and recycling or composting.
Almost zero CO2e (but the plates aren’t clean) by hand in cold water
540 g (1.2 lbs.) CO2e by hand, using water sparingly and not too hot
770 g (1.7 lbs.) CO2e in a dishwasher at 55°C (130°F)
990 g (2.2 lbs.) CO2e in a dishwasher at 65°C (149°F)
8 kg (17.6 lbs.) CO2e by hand, with extravagant use of water
> Running a dishwasher twice a week on the economy setting comes to 80 kg (176 lbs.) per year, equivalent to a 110-mile drive in an average car.
The results of the great dishwasher versus handwashing debate are as follows. The most careful hot-water handwashing just about beats the dishwasher but loses out badly on hygiene (nearly 400 times the bacteria count on the dishes) and time (four times as long as loading the dishwasher). Overall the dishwasher wins, particularly because the figures here probably don’t reflect the most energy-efficient machines that are now on the market. I also haven’t included the carbon savings that are possible if you set your machine to run in the middle of the night when electricity demand is low and the grid becomes more efficient.
The handwashing figures are based on a study of people around Europe,26 but I’ve used the U.K. electricity mix to calculate the carbon. (If you live in nuclear powered France, don’t be fooled into thinking your electricity consumption doesn’t matter so much. It all gets traded around, as discussed on page 56).
My figures for the dishwasher are based on always running a full load, and they include 130 g CO2e for the wear and tear on the machine itself (based on a fairly expensive “built to last” model that you keep for 10 years27). The conclusion, then, is get a dishwasher. It simultaneously helps the planet, your health, and your lifestyle. When you buy one, choose a make that will last, and look after it. Try to always run it full, use the economy setting when possible, and run it in the middle of the night if you can, because the electricity is less carbon intensive.
I haven’t included anything for the detergent or the domestic water consumption, because they are nothing compared with the impact of heating the water.28
A final note: I have known people routinely wash their stuff by hand before putting it in the dishwasher. This must be the worst of all options and ranks alongside ironing your spouse’s socks for needless slavery (see Ironing). If this is your routine, please consider yourself liberated.
450 g CO2e recycled paper
730 g (1.6 lbs.) CO2e virgin paper
> If you have typical North American wiping habits, that comes out at 75 kg (165 lbs.) CO2e per year or three-quarters of a percent of the 10-ton lifestyle.
The typical North American supposedly uses 57 sheets of toilet paper per day. That seems excessive to me, although I haven’t been counting. The figure comes from the ToiletPaperWorld.com website, and surely they must know these things.29 The Worldwatch Institute puts annual consumption at 23 kg (50 lbs.) per year for a North American, 1.8 kg (4 lbs.) per year for an Asian, and just 400 g for the average African.30
I’m not sure I want to launch into a detailed exploration of bathroom technique here, but because three-quarters of a percent of the 10-ton life seems high for such a simple and brief part of our lives, it does seem worthy of a moment’s personal reflection. My numbers show that a sense of economy is in order. If, as I suspect, many of us could halve our usage without any negative side-effects, then it’s an easy and worthwhile carbon win.
I’m not advocating hardship here— just calling for a simple perspective check; are our backsides in their rightful place, or are they getting spoiled? Have decades of ads talked us into believing that a pampered bum is one of the hallmarks of a rich and fulfilled life? My footprint figures here are based on numbers from Tesco, whose research suggests a carbon cost of 1.1 g per sheet for their recycled stuff and 1.8 g for traditional paper. So that’s three spam emails for a sheet of recycled, 31 five for virgin, or two sheets of virgin for one genuine email.
350 g CO2e a Fiat 500 doing a steady 60 miles per hour
850 g (1.9 lbs.) CO2e an average U.S. car achieving a typical 22.4 miles per gallon
2,500 g (5.5 lbs.) CO2e a Mercedes Benz SUV, new but not looked after, doing 90 miles per hour
> So driving a vehicle 10,000 miles would use between 35 and 250 percent of the 10-ton lifestyle, depending on what you drive and how you drive it.
At the low end of the scale, for four people traveling together in a well-maintained low-emission vehicle (such as a Fiat 500) traveling at a steady 60 miles per hour and a fuel efficiency of 43 miles per gallon, the carbon comes out at 86 g CO2e per person mile.
At the high end of the scale we have a single person in a poorly maintained, rapidly depreciating, high-emissions car that looks more like a tank, cruising at 90 miles per hour or driving unsympathetically in urban conditions with heavy use of both brakes and accelerator. In these conditions, a vehicle of this type may achieve as little as 7.5 miles per gallon.
My numbers are higher than those you normally see for driving. That is partly because I am including the emissions from the extraction, refining, and transportation of fuel, as well as just the burning of it. Even more importantly, I am factoring in the manufacture and maintenance of the vehicle itself.
As a rule of thumb, about half of the carbon impact of car travel comes out of the exhaust pipe itself.32 A few percent come from the processes of extracting, shipping, refining, and distributing the fuel (see Gasoline). The rest, typically 40 percent of the footprint, is associated with the manufacture and maintenance of the car. Big, expensive new cars have more of their embodied emissions attributable to each mile of driving. An older car that is still fairly efficient could beat a new Fiat 500 by virtue of having had its embodied footprint written off. (See New car.)
But it’s not just what model you drive that matters. Here are 10 good ways to reduce the carbon footprint of your car use:
> Use the train, bus, or bike if traveling alone. Typical savings: 40 to 98 percent. (See New York City to Niagara Falls return.)
> Put more people in the car. This could make it better than train travel, provided that the others were otherwise going to drive separately. Typical savings: 50 to 80 percent.
> Join a car-sharing scheme.
> Drive a small, efficient car. Typical savings: 50 percent compared with the average car.
> Look after your car so that it will do 200,000 miles in its lifetime and it runs as efficiently as it can. Typical savings: 30 percent compared with the average. (See New car.)
> Accelerate and decelerate gently, avoiding braking where possible. Typical savings: up to 20 percent in urban conditions.
> Drive at 60 miles per hour on highways and freeways. Typical savings: 10 percent compared with 70 miles per hour.
> Keep the windows up when driving fast, and the air-conditioning off. Typical savings: 2 percent.
> Keep the tires at the right pressure. Typical savings: 1 percent.33
> Avoid rush hour. (See Congested car commute.)
> Drive safely. (See Car crash.)
Is it worth slowing down?
Although we might know that driving more slowly on highways is better for the planet, this concern often gets outweighed by our desire to get there on time. After all, time is money, right?
I’m going to take the case of someone driving on their own and assume that they value their time at $24 per hour. That’s about the take-home pay per hour of someone earning $60,000 for a 37.5-hour working week plus a half-hour highway journey (around 35 miles) to the office each way. This is above average for the population as a whole but may be about typical for those who commute on highways.
I have assumed that the commuter in question drives a car that is capable of 33 miles per gallon at 70 miles per hour but 45 miles per gallon at 60 miles per hour. That is reasonable because, in highway conditions, the fuel consumption is roughly proportional to the square of the speed.34 I’m also going to assume that this person hardly cares at all about their impact on climate change (we’re going to look at financial costs and benefits only) and that the carbon cost of gasoline is 3 kg (6.6 lbs.) CO2e per liter, or about 11 kg (25 lbs.) CO2e per gallon (see A quart of gasoline).
As Table 4.2 shows, in this scenario, the slower driver saves carbon but loses a bit of money. In the U.K., where fuel is more expensive, the driver breaks even by slowing down. Those less well off or with hungrier cars would be better off as well.
| 70 mph | 60 mph | |||
| Value of driver’s time, per hour | $24 | $24 | ||
| Miles per gallon | 33 mpg | 45 mpg | ||
| Carbon footprint of a 70 mile round-trip commute | 21 kg (46 lbs.) CO2e | 16 kg (35 lbs.) CO2e | ||
| Time cost of the 70 mile commute | $24 | $29 | ||
| Cost of gasoline | $6 | $4 | ||
| total cost | $30 | $33 | ||
TABLE 4.2: How to save carbon without losing money.
Electric and hybrid cars deserve a mention. Let’s be clear. The electricity has to come from somewhere. Until such time as we have abundant renewable electricity, any additional demand for the stuff has to be met entirely through fossil fuel, rather than wind or hydro turbines whirring round faster. So, for the foreseeable future, switching from gas to electric doesn’t get you away from having a 100 percent fossil fuel–powered car. However, in principle, it does give a small efficiency gain, because although there is energy lost in the process of generating the electricity from fossil fuel and transporting it to your car, once there, an electric car can do an efficient job of turning that electricity into mechanical energy. The best gas cars, by contrast, can turn only about 25 percent of its fuel energy into motion, with the rest dissipated as heat. Electric and hybrid cars can also offer regenerative braking, generating electricity as you brake. This makes little difference on the highway but can be significant for urban driving. Overall, for the next few decades at least, electric cars stand to give us a few percent efficiency improvement but definitely not a revolution in the carbon friendliness of motoring. (See also New car.)
Zero CO2e picked from your garden, no inorganic fertilizer used
350 g CO2e grown in Colombia and flown by air
2.5 kg (5.5 lbs.) CO2e grown in a heated greenhouse in the Netherlands and then flown
> A single red rose could have the same impact on climate change as about five kilos (11 pounds) of bananas.
Could the banana ever replace the rose on Valentine’s Day? If you try this low-carbon alternative, please let me know how you fare (info@howbadarebananas.com).
The numbers here sum up the Hobson’s choice that you are faced with if you want out-of-season cut flowers. You either have to put them on a plane or grow them using artificial heat. Both of these are bad news for climate change.
The study I based my numbers on found that for consumers in the U.K., Dutch roses had about six times the carbon footprint of the air-freighted ones.35 After all, Holland is a cold country in winter and roses take a long time to grow. This only adds up commercially because the Netherlands subsidizes the energy required by its floral industry. In the U.K., home-grown flowers will probably have enjoyed only the Sun’s heat.
In my work on U.K. supermarket products, out-of-season cut flowers emerged as some of the products with the largest carbon footprint per pound generated at the tills. In other words they are one of the most carbon-unfriendly ways of getting rid of your cash.
There’s another concern, too. All commercial cut flowers use land that could otherwise be growing food. The demand for agricultural land is already driving deforestation (see A hectare (2.5 acres) of deforestation), which in turn is responsible for around 18 percent of man-made emissions. Looked at in those terms, cut flowers have to mean less rainforest—so the true footprint is probably even bigger than my numbers suggest.
Quite a few people I’ve spoken to have said that their attraction to cut flowers wilted once they made the connection with the huge emissions and pressure on land that they bring about.
So, stick to your own grown garden crop if you can, and do without flowers when they are not in season. As for alternatives, longer-life indoor plants are a dramatically less carbon-intensive option. And some artificial flowers are just about indistinguishable from the real thing—if you can bear the concept.
1 kg (2.2 lbs.) of boiled potatoes
620 g (1.4 lbs.) CO2e locally grown, boiled gently with the lid on
1,170 g (2.6 lbs.) CO2e still local but boiled furiously with the lid off
This panful of potatoes contains two-thirds of a woman’s daily calorific needs. If potatoes were all you ate for a year, you could feed yourself for just 330 kg (730 lbs.) CO2e, or 3 percent of the 10-ton lifestyle. That is good going when you consider that food and cooking currently account for 3 tons CO2e per person per year. (That’s without taking account of deforestation, which could add half as much again). You’d end up bored and malnourished if you stuck rigidly to this regime, of course, but there is clearly a place for potatoes in the low-carbon lifestyle. Table 4.3 shows how the footprint breaks down.
| Grams CO2e | ||
| Growing the potatoes | 220 | |
| Transport | 80 | |
| Packaging in a simple bag | 10 | |
| Supermarket storage and display | 60 | |
| Boiling | 250 to 800 | |
| total | 620 to 1,170 (1.4 to 2.6 lbs.) | |
TABLE 4.3: Breaking down the potato footprint.
Potatoes are a low-carbon crop; larger conventional varieties are especially so, simply because yields are higher.
Transport emissions are not high, provided these potatoes stay in the locality. It is not uncommon for some supermarkets to move produce hundreds of miles to a distribution center and then back again. Even when this happens, however, the transport does not have a disastrous impact.
The biggest part of the footprint comes from the cooking process. The way you do this can alter the total footprint by a factor of two. Here are some ways to keep the cooking emissions to a minimum:
> Use a gas stove.
> Use a lid on the pan.
> Boil gently. The temperature of the water, and therefore the cooking speed, is exactly the same when you turn the gas down to a gentle simmer as when you boil at full throttle.
> Cut the potatoes into smaller pieces.
> Use a pressure cooker: the pressure raises the boiling temperature, which means the potatoes cook faster and more efficiently.
Alternatively, if you are baking or roasting, you can:
> Use a microwave or a convection oven.
> Reduce the size of the pieces.
> Having heated the oven up, cook more than one thing.
I have ignored the carbon cost of getting to the store (see Driving 1 mile, and Cycling a mile).
723 g (1.6 lbs.) CO2e
> So if you get through two pints a day in your household, that’s 527 kg (1,160 lbs.) per year, as much as a return flight from San Francisco to Vancouver.
Milk is high-carbon stuff for exactly the same reasons that beef is. Cows, like most animals, waste a lot of the energy in the food they eat in the process of simply keeping warm and walking around rather than creating meat and milk. In addition, cows ruminate (chew the cud), which means they burp up methane, roughly doubling the footprint of the food they produce.36
As Figure 4.7 shows, around 85 percent of the milk’s footprint is generated on the farm, but transport, packaging, and refrigeration also play their part. Because milk is heavy, keeping it local (and not trucking it hundreds of miles to and from distribution centers) seems like a good idea. My instinct is that milk delivery services probably cut carbon footprints by keeping the weight of our shopping bags down and therefore making it that much easier to walk to the store for everything else. In addition, reusable glass bottles almost certainly beat plastic disposables, even if you recycle the latter every time.
Wherever you get your milk, however, it remains—like all food from cattle—a high-carbon way to get your calories. There is probably quite a lot that could be done to reduce its carbon cost, but it’s a hugely complicated area to research. Various studies have been carried out so far, but they don’t always agree. To give a flavor of how confusing everything is, if you change the feed, you alter the carbon cost of that feed, the milk yield, and the amount of methane that gets belched out. At the same time you play about with factors like the life expectancy of the cow, the amount of saleable meat that the herd will produce alongside its milk, and the other inputs that will be required to keep the cow healthy. To make things even more complex, different farming practices affect the ability of the soil to absorb and store carbon. And everything also depends on the location of the farm and the breed of cow. Nobody has yet properly worked out how all these variables interact.
If the carbon footprint were the only consideration, the unpleasant truth is that the most efficient thing to do would probably be to keep cattle in small indoor spaces and rear them as intensively as possible, minimizing wasteful activities such as getting exercise or keeping warm. But carbon isn’t the only consideration, of course, especially for organic farmers such as David Finlay in southwest Scotland. David is reducing the milk output of his herd in southwest Scotland from 7,500 liters per cow per year to 5,000 (1,980 gallons to 1,320 gallons). He believes that although the milk yield will go down, the amount of meat he can sell will go up and his feed costs will fall, along with his use of antibiotics and other inputs that have both financial and practical costs. Hugely important to David are two other factors: the animals will have even better lives than they already have on his farm, and he stands to have more free time because he will only have to milk them once a day. He believes a system like this could compete in the supermarkets alongside conventionally farmed milk even without the organic label. In fact, he believes the price premium on the organic label comes mainly from the administrative costs of demonstrating at every step of the journey from farm to shop that no contamination with conventional milk has taken place.
FIGURE 4.7: The carbon footprint of locally sourced milk in a plastic bottle at the checkout of Booths Supermarkets. In this example, the milk comes from Bowland Fresh, a local supplier, so the transport impact is low. This chart doesn’t include either your journey to the shops or home refrigeration.
One partial solution to the belching problem, legal in the U.S. since 2004 and widely used, is Rumensin, a simple additive that markedly cuts methane production in cows. The EU classified it as an antibiotic and banned it, even though the farmers I’ve spoken to say this was a mistake because it does not have the human health impacts usually associated with antibiotics. I’m not an expert on these things, but I can believe this might possibly have been a bureaucratic blunder that is now waiting to be overturned.
Whatever the truth about different dairy farming practices, soy milk is almost certainly a lower-carbon option than anything from a cow. Even though I haven’t seen a study of this, in comparison with cows’ milk, there is none of the inefficiency of putting animals in the food chain and no rumination involved. The market for soy is driving deforestation, but the problem is not the stuff that is eaten directly by humans: most soy is fed to... cows.
100 g CO2e Eco-Cement
710 g (1.6 lbs.) CO2e standard cement, efficient production
910 g (2 lbs.) CO2e global average
1 kg (2.2 lbs.) CO2e inefficient production
The world produces around 2.2 billion tons of cement per year—or around 300 kg (660 lbs.) per person. Nearly half of this (47 percent) is produced in China. Making this basic building material results in a staggering amount of CO2e: around 4 percent of the world’s total greenhouse gas footprint.37 This figure is so high because the chemical process that turns limestone into cement gives off large volumes of CO2 directly and takes a huge amount of energy.
Around half the footprint is down to the chemical reaction. There is not much you can do to reduce this without changing the product itself. About 40 percent comes from the burning of fuel to drive the reaction, leaving 10 percent for other bits and bobs in the cement industry and its supply chains.
Because of the basic chemical reaction required to make the stuff, it is hard to see how conventional Portland cement could be made into a low-carbon product. One alternative is Eco-Cement, a product invented by John Harrison in Tasmania. Eco-Cement’s advocates claim not only that this product requires half the energy input of conventional cement but also that it reabsorbs CO2 from the air as it hardens (around 400 g CO2e per kilo). There are also claims that it is easier to incorporate waste materials into the mix than with normal cement and that it is easier to recycle. The product is based on magnesite, which is not as abundant as limestone, and perhaps that’s why not everyone is using it yet. Or perhaps it is no good at sticking things together. I haven’t tried it.
Cement makes up about 12 percent of the footprint of the U.K. construction industry, so other potential ways of reducing its impact are to use different materials, to build to last and build less, and to refurbish in preference to knocking down and building anew (see House).
* Update: we survived. It was horrible. I’m going to pick different battles. A little bit more herbal tea is drunk in the office these days, possibly as a result of the experiment.