10 kilos to 100 kilos
(20 pounds to 200 pounds)
1.5 kg (3.3 lbs.) CO2e Crocs
8 kg (17.7 lbs.) CO2e synthetic
11.5 kg (25.4 lbs.) CO2e average
15 kg (33 lbs.) CO2e all leather
> Imelda Marcos’s collection of 2,7001 pairs of shoes would have had a carbon footprint of around 30 tons, or 3 years’ worth of 10-ton living—assuming, of course, that they had all been typical shoes.
As the numbers here show, shoes vary enormously in their carbon footprint (no pun intended). Just as important is their longevity.
At the low end of the carbon scale are Crocs, the simple and surprisingly durable shoe consisting of just 250 g of expanded EVA (ethylene-vinyl acetate) and sold without packaging. For these shoes, the raw material comes in at just over 1 kg (2.2 lbs.). The rest is a guesstimate.
The 8 kg (17.7 lb.) synthetic pair is based on a study of synthetic cross-country running shoes, made in China but traveling to market by boat. My average figure, meanwhile, is based on the input-output model (see Environmental input–output analysis) and a price of $75 per pair. The model tells us that in the typical shoe about half of the carbon footprint is due to materials, around one- quarter is due to energy used in shoe manufacture, 15 percent is transport, 5 percent the shoe box, and 5 percent other bits and bobs.2
I have estimated the higher figure for all-leather shoes on the basis of the carbon intensity of cattle farming.
Most of our footwear comes from the Far East, although specialist leather might also have had to travel a long way to get there. Shipping is fairly efficient. The big inefficiency in transport comes if a product is air-freighted for speed. This is most likely in high-end fashion, though unfortunately there’s no way to be sure as a consumer what has and hasn’t been delivered from the country of origin by plane.
12 kg (26 lbs.) CO2e hard cheese
> That’s about 3 kg (6.6 lbs.) CO2e for a big 250 g (8 oz.) block from the store—equivalent to a 4-mile drive or a massive 12 kg (26 lbs.) of carrots.
It takes about 10 quarts of milk to make 1 kg (2.2 lbs.) of hard cheese, adding up to a considerable carbon footprint that’s higher than that of many meats. The message is clear, then: going veggie doesn’t reduce your impact if you simply swap cheese for meat. Neither will it save you money nor make you healthier. Perhaps the best advice if you’re keen to reduce the climate impact of your diet is to think of cheese as a meat and therefore a treat. Many people will also improve their life expectancy by cutting back somewhat.
However much cheese you eat, there’s an easy carbon win by keeping waste to a minimum. That means buying only what you think you’ll actually get through and also avoiding trashing hard cheese just because it’s showing a tiny sign of mold. This is perfectly safe according the U.S. Food Safety and Inspection Service, which must surely be among the most cautious groups around:
Discard any soft cheese showing mold. For hard cheese, such as Cheddar, cut off at least 1 inch around and below the mold spot (keep the knife out of the mold itself). After trimming off the mold, the remaining cheese should be safe to eat. Re-cover the cheese in fresh wrap and keep refrigerated.3
As for which hard cheese to buy, the most sustainable types probably come from cows that have grazed almost exclusively on rough pasture that couldn’t have been used for crops—though of course that information isn’t generally available in the stores.
Note that which country or area the cheese has come from doesn’t matter much when set against the impact of the milk production (see A pint of milk). Hence the easiest way to reduce the carbon footprint of your cheese is to opt for soft cheeses, because these require less milk to produce.
22 kg (49 lbs.) CO2e five miles of crawling each way in an average car
> Every working day for a year would be 4.8 tons CO2e more than flying from Los Angeles to Barcelona and back. A congested drive can cause three times the emissions of the same drive on a clear road.4
Driving in a traffic jam very roughly doubles your fuel consumption per mile. However, that’s only half of the story. By adding your car to the mass of ugly, belching motors, you also make a lot of other people line up just a little bit longer. It turns out, via a bit of simple queuing theory,5 that the extra emissions you force everyone else to produce (when you add them all together) is about equal to the extra emissions that you produce yourself as a result of having to line up instead of being able to drive straight through. In other words, if your journey is congested, by choosing to do it you cause about three times more emissions than you might expect.
The queuing theory logic also works for the time that gets wasted. If you make the assumption that the journey is many times longer than it would be if there were no traffic, then the time you waste in the line is about equal to the sum of the extra time you make everyone else waste. In other words, the hassle and anguish that you experience is equal to the hassle and anguish that you inflict. So when deciding whether to drive through a busy area at rush hour, picture your own pain and double it.
All of this adds to the case for traveling by bike, bus, train, foot, or ride share wherever possible. It’s also a useful reminder that all motorists should treat cyclists with the respect they deserve for helping to cut everybody else’s journey time.
Where you must drive in busy conditions, do your best to minimize stops and starts—both your own and everyone else’s. A steady slow stream of traffic is more efficient than a faster but less steady one unless the stops are so long that everyone can turn their engines off. One good tip is to think about what to do when two lanes merge: to reduce emissions, ease your speed down, merge gently and in good time, and allow others to do likewise. In theory at least, two lanes traveling at 50 mph can carry about the same traffic as 3 lanes traveling at 70 mph, assuming that everyone leaves a safe stopping distance between them and the next vehicle. This is because slower cars need less distance between them.6 It’s good to minimize the use of brakes on the highway if you can. And when you pass other vehicles, put your signal light on in good time too, so that no one else has to brake either.
3 kg (6.6 lbs.) CO2e low-carbon scenario
24 kg (53 lbs.) CO2e $100 spent on dinner, drinks, bed, and breakfast in a hotel with average eco-credentials
60 kg (132 lbs.) CO2e high-carbon scenario
For my high-carbon scenario I have chosen one of those hotels where the TV and six lights are already on when you walk into your room. The room itself is too hot and you cool it by opening the window even though the radiator is on. There is a swimming pool, with air-conditioning. You order beef or lamb for dinner and it arrives with baby vegetables air-freighted from Peru. There is too much for you to eat. For dessert you have strawberries even though it is winter. In the kitchens, half of the food cooked is thrown out at the end of the night. You stay one night, finding your way through three towels as well as your sheets. You have a fried breakfast, giving the paper you ordered a quick glance before leaving it on the table (from where, surely, even in this hotel, it goes for recycling).
The low end of the scale could be a large, very well run hotel or, more likely, a simple bed and breakfast with thoughtful owners. If you stay a few nights, your sheets and towel aren’t changed unless you ask. The room is comfortable, and you can adjust your own heating. You opt for a low-meat-and-dairy meal with seasonal vegetables, and you get to choose how much goes onto your plate. Leftovers end up in the next day’s soup. You have something like cereal or muesli, fresh fruit and toast for breakfast. There is a selection of papers shared between guests (with the added advantage that you get to browse several if you have time). What you are paying for is a more personalized service in which you can have what you require without its being thrown at you just in case. The difference in carbon footprint between these two scenarios might be as high as a factor of 20.
The British clock up 42 million tons of emissions through their use of hotels, pubs, cafés, and restaurants (Figure 6.1). That’s nearly 5 percent of the national carbon footprint. What the British drink when they are out has almost as much impact as what they eat, and both of these have a bigger footprint than the energy used by the establishments where the eating and drinking happens.
FIGURE 6.1: The 42-million-ton footprint of the U.K.’s hotels, pubs, and catering industry.
As a rule of thumb, the hotels, pubs, and catering industry in the U.K. has a footprint of about 400 g CO2e for every pound you spend. North America is probably similar at around 270 g per dollar. Roughly speaking, this seems to be true whether it is food, drink, or accommodation that you are buying. However, this is just a general figure, and the footprint certainly doesn’t have to go up or down with the price. Indeed, there is a lot that the carbon-conscious consumer can do to keep emissions down, simply by spending money in establishments that think about the issues.
When eating out, look for seasonal fruit and vegetables, and choose places where the lower-meat and lower-dairy options are cooked with at least as much passion as anything else. The restaurant should be taking steps to minimize food waste both on your plate and behind the scenes. In a hotel, look for good energy management, minimization of laundry and a general sense of care with resources. In a pub, look for local cask beer.
For any hotels, pubs, or restaurants seeking to understand their carbon footprint, a colleague and I have built and tested a carbon calculator especially for tourism businesses and have made it freely available online.7
38 kg (84 lbs.) CO2e a 2 kg joint at the checkout
> For the same carbon footprint, you could have a bowl of porridge (made with half milk, half water) every day for 4 months.
Lamb comes in with a carbon footprint of about 17 kg for each kilo (7.7 kg for each pound) produced at the slaughterhouse. Transport, basic processing, refrigeration, and a little bit of packaging each add a little bit, so that by the time the meat reaches the checkout, the footprint has increased by about 10 percent. You will add a similar amount again by the time you have picked it up from the store, put it in the fridge and cooked it, taking the overall carbon impact to more than 20 kg per kilo (9 kg CO2e per pound).
The issues surrounding sheep are very similar to those relating to cows (see Steak, and Milk). Like cows, sheep ruminate, releasing large quantities of methane. And just as with beef farming, the exact impact of different types of sheep farming is complex and only partly understood. Hill farmers can claim that they are putting otherwise unproductive land to use. Some also claim that putting sheep on the hills helps the soil to absorb carbon from the air. Counterarguments are that hill-farmed sheep are inefficient, that they spend too much energy wandering around, eating low-energy food and keeping warm and that therefore they burp more methane per joint of meat than their lowland counterparts.
It seems probable that, from a broad sustainability point of view, hills are the best places to have sheep. But ultimately only one thing is clear: a low-carbon world is going to have to involve less lamb. The typical footprint of this meat is even higher than that of beef. The low-carbon choice is to think of lamb as a treat and to eat less of it.
76 kg (168 lbs.) CO2e thin polyurethane carpet with thin underlay, 4 m x 4 m (13 ft. x 13 ft.)
290 kg (639 lbs.) CO2e the same area covered in thick wool, polypropylene, or nylon with generous underlay
> If you have 50 m2 (540 sq. ft.) of top-end carpet in your house, that could add up to 900 kg of embodied emissions—equivalent to a burger a day for a year.
Provided you get full wear out of them, some carpets may well pay for themselves in carbon terms, by improving your insulation. However, if you are in the habit of moving house every couple of years and insisting on stripping out everything that was there to replace it with styles more to your own taste, then carpets, along with other soft furnishings, could be a significant chunk of your total carbon footprint.
Table 6.1 gives some figures for the footprints per pound of fabric materials, based on studies of European production.8 In the U.K. most textiles come from developing countries, not least China, where industry is typically a lot more carbon intensive. For Chinese production you can probably mark most of these up by a factor of two or three on the basis that the factories tend to be less energy efficient, and the electricity they use is also more carbon intensive per unit because so much of it comes from coal-fired power stations. I’m not writing this out of some kind of protectionist instinct—just presenting the facts as I see them. I’d like to see China develop—but not at any cost.
| Carpet type | Carbon footprint | ||||
| (kg CO2e per kilo) | (kg CO2e per pound) | ||||
| General | 3.89 | 1.77 | |||
| Felt underlay | 0.96 | 0.44 | |||
| Nylon | 5.43 | 2.47 | |||
| PET (polyethylene terephthalate) | 5.55 | 2.5 | |||
| Polypropylene | 5.03 | 2.29 | |||
| Polyurethane | 3.76 | 1.71 | |||
| Wool | 5.48 | 2.49 | |||
TABLE 6.1: Carbon footprints of carpet types.9
To give a sense of what the numbers mean in practice, typical weights are 1 to 1.5 kg per square meter (93 to 140 g per square foot) for underlay and 1 to 3 kg per square meter (93 to 280 g per square foot) for the carpet itself. This puts the overall footprint in the region of 5 to 18 kg per square meter (1 to 3.6 lbs. per square foot).
47 kg (103 lbs.) CO2e a year’s typical usage of just under 2 minutes per day
1,250 kg (2,760 lbs.) CO2e a year’s usage at 1 hour per day
125 million tons CO2e global cell phone usage per year
> A minute’s cell-to-cell phone chatter comes in at 57 g,10 about the same as an apple, most of a banana, or a very large gulp of beer. Three minutes have a similar impact to sending a small letter (written on recycled paper) by regular post.
Cell phones cause a fairly tiny slice of global emissions, but if you are a chatterbox using your cell phone for an hour each day, the total adds up to more than 1 ton CO2e per year—the equivalent of flying from London to New York, one way (economy class).
Indeed, the footprint of your cell phone use is overwhelmingly determined by the simple question of how often you use it. One estimate for the emissions caused by manufacturing the phone itself is just 16 kg (35.3 lbs) CO2e,11 equivalent to nearly 1 kg (2.2 lbs.) of beef. If you include the power it consumes over two typical years (that’s about how long the average phone remains in use, even though most could probably last for 10 years) that figure rises to 22 kg (49 lbs.).12 But the footprint of the energy required to transmit your calls across the network is about three times all of this put together, taking us to a best estimate of 94 kg (207 lbs.) CO2e over the life of the phone, or 47 kg (103 lbs.) per year (Figure 6.2).
FIGURE 6.2: The 47 kg annual carbon footprint of mobile usage, based on a Nokia n7600 phone used for 2 minutes per day and replaced after 2 years.13
In 2009 there were 2.7 billion cell phones in use: nearly half the world population has got one. On this basis, cell phone calls account for about 125 million tons CO2e, which is just over one-quarter of a percent of global emissions.14
If you want to reduce the footprint of your communication habits, texting is a much lower-carbon option (see A text message). Landlines offer carbon savings, too, because it takes about one-third of the power to transmit a call over a fixed landline network than it does when both callers are on a cell phone.15
It took a lot of digging to get data for this entry. In the end I was pleasantly surprised that there is some reasonably sensible-looking analysis out there. Nevertheless, now feels like a good time for another reminder that all footprint estimates contain considerable uncertainty, and some even more so than others.
80 kg (176 lbs.) CO2e
> That’s less than one ten-thousandth of your life’s carbon footprint.
My advice would be to treat yourself on this one occasion to whichever method takes your fancy. This is the one time when it is too late to start worrying about your carbon footprint. And anyway you have already done the most carbon-friendly thing possible. However, this book is about doing the numbers, so here goes.
The Guardian reported that the average cremation uses 285 kilowatt-hours of gas and 15 kilowatt-hours of electricity, and I’m going with that. I have not included emissions from your own flesh, because your body was only ever a temporary carbon storage device.* On top of the carbon, cremation sends significant amounts of mercury into the atmosphere.
Burial sounds like a more climate-friendly solution, but browsing blogs on this subject (yes, there really are people who write these) I found a clergyman who reckons that burial turns out 10 percent higher carbon once you take account of cemetery maintenance for the next 50 years. I have managed to resist checking these sums myself.
A sea burial sounds ideal if you don’t mind the possibility that some of your loved ones may be heaving over the side when they are supposed to be paying you their last respects. There are usually legal problems with this method, however.
If what you most want to do is send a final eco-message to the world, the best answer I know of is to be dressed in easy-to-rot clothing and put in a wicker coffin. In some countries it is possible to be buried in woodland with the idea that your remains will become trees—a lovely idea, though if everyone tried this we might run out of room. Check the legality In your part of the world if this is of interest.
* If we start getting into this, losing weight will become a source of guilt. Perhaps even a bit of reverse psychology will kick in and alleviate the western obesity pandemic.