It's carbon judgment day

The news is constantly full of talk about 'carbon footprints' - but do you actually know how big yours is? Find out whether you're a green angel or a carbon criminal with Mark Lynas's step-by-step guide

Now that the size of Tony Blair's carbon footprint has finally been established (clue: it's big), we can all feel good about ourselves at last. We can't all be that bad, surely? We haven't been invited to Bee Gee Mansion in Florida recently, nor have we hung out with Cliff in Barbados too many times over the past year. But then, there was the weekend break in Barcelona ... and a year's worth of school runs ... not to mention the heating bills for the second home in the Cotswolds ... oh dear.

Today is carbon judgment day: it is time to find out just where you lie on the carbon emissions scale. No ifs, no buts, no excuses. With the government mulling over possible national carbon rationing schemes, we will all need to get more carbon-literate over the coming years. Are you a low-emitting green angel, or the new Jeremy Clarkson? George Bush, or George Monbiot? It's time to find out the truth.

First, you need to assemble the evidence. A pen and a piece of paper would be handy too. Let's start with your house. Dig out a year's worth of gas bills if you use gas for central heating and cooking. We'll also need a year of electricity bills and any other fossil fuels you use domestically, such as oil for your boiler or coal for your Aga (God forbid!). The second area to look at is transport. If you own a car, we need the mileage and model to make an emissions estimate. If you don't write down distances driven (and who does?), find your two most recent MoT certificates - they'll give you the overall mileage driven in the year, and you can base an estimate on that. Then think back to your holidays, and any regular commutes you do, to get the gist of your year's worth of travel.

1. Gas and heating

Heating is the biggest user of energy in domestic households, accounting for 70% of the energy we use, so reducing it is the best way to get your total down. Yes, we know all about wearing extra jumpers and turning the thermostat down by a degree, but if you actually want to feel comfortable in your home, the three things to think about are insulation, insulation, insulation. If you're in a post-Victorian home, make sure your cavity walls have been done. All lofts should also be insulated to a minimum depth of 30cm, and any more fibreglass you can stuff up there will make your house warmer still. If you are a pensioner or on benefits, you can get grants for this from the government. All this will help you burn less gas.

So let's start with your gas bills. They'll generally be quarterly, and we need the figures for kilowatt-hours (kWh) from the bill, rather than units from the meter.

To give you an idea of how profligate or thrifty you are, here are some bog-standard averages, for the average house inhabited by Mr and Mrs J Public in Privet Drive, Godalming, Surrey.

Small house: 10,000kWh per year.
Medium house: 20,500kWh per year.
Mansion: 28,000kWh per year.

To convert your kWh into carbon emissions, multiply the total by 0.19, and for your personal total, divide by the number of adults in the house.

Write down your carbon footprint from gas

"But I don't use gas for heating," I hear you object. Don't worry.

If you've got an oil-burning boiler, find out the number of litres you use in a year and multiply this figure by 2.975.

Oil is more carbon-intensive than gas, so people using oil for space and water heating will probably have a higher carbon footprint than those using gas in their houses. But the worst possible option is to use coal: coal is nearly pure carbon, and when you burn it, you get nearly pure carbon dioxide. (Gas, on the other hand, because it has hydrogen atoms in its molecules, produces a lot of water - H2O - when burned.) So take the total weight of coal burned in kilograms and simply double it to get the carbon dioxide emissions.

Write down your carbon footprint from heating oil and your carbon footprint from coal

But what if you burn wood? Well, the emissions impact of this is questionable. There is a degree of local pollution from wood smoke to worry about (it smells nice, but many of the particles in wood smoke are highly carcinogenic), but in terms of greenhouse gases, any effect is countered by the regrowing of the trees that were cut down for the logs in your fire. So unless your logs came from a tropical forest clear-cut and which won't be replanted, you can count wood as zero carbon impact. Hooray!

2. Electricity

The other big use of power in the home is, of course, electricity. Domestic electricity use just keeps on rising, largely because of our insatiable appetite for more electronic gadgets. Between 1972 and 2002, electricity use in the household sector doubled, and is projected to rise another 12% by 2010. You don't have a cappuccino maker? Pah! Get with it.

Then there is the standby issue: televisions and digital set-top boxes may never be switched off at the wall (though they should be); hi-fi equipment keeps on humming away long after the Abba Gold CD has played out; phone chargers left plugged in by the kids continue soaking up power too - touch them and you'll see they feel warm. That warmth is electricity, going to waste.

So, we need your electricity bills - like gas bills, these are usually issued quarterly. If you can't find them, your supplier should still be able to give you a useage figure over the phone (if you can ever get through to the call centre, of course). Figures should be in kilowatt-hours again, please.

And here are Mr and Mrs J Public's national averages.

Small house: 1,650kWh per year
Medium house: 3,300kWh per year
Bee Gee Mansion: 5,000kWh per year

To convert this figure into carbon emissions, multiply by 0.43. Don't forget to divide this by the number of adults in the house to get your personal figure. (Now you can see how living alone hugely increases someone's ecological footprint, while house- sharing can halve it at a stroke.)

Write down your carbon footprint from electricity

What if you're on a green tariff? This is another grey area. Most green tariffs offered by the big electrical suppliers simply charge you a premium - often matched by the company - which goes into a fund to support renewables projects. This is good, but it doesn't make you carbon-neutral. A greener option by far is offered by the smaller company Good Energy, which pledges to match your electricity use with 100% renewable power. If you're signed up with them, you can put a zero in the box above. Another good option is Ecotricity, which spends more per customer than any other company on new renewable investments.

3. Transport

Cars are the bete noire of all environmentalists, and for good reason. Car culture, as well as being unhealthy and ecologically destructive, is self-perpetuating. Before cars were in widespread use, shops or amenities tended to be within walking or cycling distance, within a tightly defined community. Now, with suburban sprawl and the rise of out-of-town shopping, people may have to drive miles to get a pint of milk or a loaf of bread. The average shopping trip in Britain is 4.3 miles - hardly a walkable distance. And the supermarkets tell us it's all about convenience. Hmm.

Road transport accounts for fully a fifth of the UK's entire national carbon emissions, totalling 33m tonnes in 2004. Road traffic in the UK is on an unrelenting upward trend, and has increased by 10% since Labour came to power in 1997. Because politicians are terrified of being labelled "anti-car" by the motoring lobby, little has been done to persuade people to use public transport or travel less often. Indeed, the economics stack up against it: the real cost of motoring fell by 9% between 1997 and 2005, while bus fares increased by 15% and rail fares by 5%. The government now spends £1bn a year on expanding the road network, despite knowing that this will increase traffic further. And yes, this money could have built an awful lot of wind turbines and solar panels, and insulated a lot of people's houses. Shame, that.

Now let's calculate your car's carbon emissions. Apart from your mileage, the most important factor here is the type of car you drive. If it's a Jag or a Humvee, then your total's going to be pretty high. To get your total, we need to multiply your mileage by the car's emissions per mile - you can't be expected to know this offhand, so the best thing to do is to find your car model and type on the online database at This will give you a figure for emissions in grams per kilometre. Write it down.

Now multiply this figure by the number of kilometres you drove over the year. (If you're starting with miles, multiply this by 1.609 to get, er, "kilometreage".) Then divide by 1,000 to get the total in kilograms. (Again, make sure this is your personal total - so halve it for journeys made when you shared the car with another adult, for example.)

Write down your carbon footprint from driving

Of course, public transport also has a carbon cost attached to it. We're accustomed to thinking of trains as "good", but many people don't know that a small car with three people in it is more efficient per passenger mile than most trains. Trains also generally cover greater distances, so you probably can't afford to skip this part of your carbon budget, tedious as it may be to try and calculate. (Doing your tax return will be a breeze after this!) One time-saving option might be to decide on an average week and multiply it by 52. Regular commuting journeys are easier to tot up, and for occasional bigger journeys you can find the distances between different towns in the UK by using the AA online route planner at Don't give up - we're nearly finished.

Again, we need kilometres, so multiply mileage figures by 1.609. When you've finished, add up all your carbon cost figures to find out your total.

Kilometres travelled by train
Multiply by 0.11 for carbon cost
Kilometres travelled by bus
Multiply by 0.09 for carbon cost
Kilometres travelled by underground
Multiply by 0.09 for carbon cost
Kilometres travelled by ferry
Multiply by 0.47 for carbon cost

Write down your carbon footprint from public transport

There. That's done. But wait - haven't we forgotten one very large and increasingly controversial area of emissions? Ah yes: flights. Britain's CO2 emissions from aircraft doubled in the space of a decade between 1990 and 2000, and are projected by the government to double again by 2030. (This is a prophecy that ministers seem determined to make self-fulfilling with their policy to hugely expand airport capacity throughout the country, encouraging still more people to fly.) Aviation's impact on the climate is worsened by fact that jet emissions happen high up in the atmosphere, where they can do most damage. The greenhouse impact of carbon dioxide is also augmented by warming from water vapour in contrails too, as well as other gases emitted by aircraft. In total, the Intergovernmental Panel on Climate Change estimates that direct CO2 emissions from aircraft need to be mulitplied by a factor of 2.7 to account for the full warming effect of flights.

The reason that flying is so controversial among environmentally aware people is that a single long-haul return flight - say, from London to Sydney - will, by itself, double most people's carbon footprint for the entire year. It's not that aircraft are uniquely bad - indeed, the per-mile emissions are comparable to driving a car the same distance - but that the distances involved are so huge. It is because flights allow us to travel so many thousands of miles in just a few hours that their carbon cost is so high. Having said that, don't imagine that short-haul flights are a good way to get around either, because proportionally more fuel is used in take-off and landing, so short-haul flights are really the worst of all possible transport options.

If you're reasonably map-literate, the best way to calculate your carbon emissions for any flights you have taken is to visit the website It lets you click your departure point and destination, and does all the calculations for you, with the aviation-emissions multiplier included. Alternatively, if your geography isn't up to finding Lima or Milan on a map of the world, there are plenty of other easy-to-use carbon calculators on the web: from the carbon offsets company Climate Care is probably the best, though it will give a slightly lower total for the same flight than Choose Flying, because less of a multiplier is factored in.

Now take a deep breath, and enter your carbon emissions (in kilograms) from flights in the past year.

Write down your carbon footprint from flights

4. Consumption

We've done household emissions and we've done transport. But add these two together and they comprise only two-thirds of the UK's national emissions. The missing third comes from the industrial sector: manufacturing, retail and services. Every item you buy, from strawberries to CDs, has an energy penalty associated with it: the energy in gathering the raw materials, in processing and manufacturing, transporting and then selling it to you. (Not to mention all those advertising execs sitting in their heated offices in Soho doodling and figuring out how to sell you all this stuff you didn't know you needed in the first place.)

You won't find this energy penalty quantified on the label, so even if you wanted to you wouldn't be able to go rifling through all your cupboards adding together the damage for each can of baked beans or pair of knickers. So here we really do have to make an informed guess.

Calculations by George Marshall, carbon lifestyle specialist at the Climate Outreach and Information Network, give us the following shorthand guesstimates:

· I have the latest of everything, love shopping and eat mostly packaged convenience food: add 3,000kg.

· I'm fairly thrifty, but buy new things when I need them and get most of my food from supermarkets: add 2,000kg.

· I mostly grow my own organic food, shop locally, reuse and recyle, and wouldn't touch out-of-season green beans with a bargepole: add 600kg.

So it's your call. If you lie somewhere in between on this scale, feel free to estimate your own figure. (If only the Inland Revenue was so forgiving.)

Write down your carbon footprint from consumption

5. The bottom line

It's now (drum roll) time for the moment of truth. Go back over these pages and add all the figures together. This should give you a grand total, in kilograms, of carbon emitted during a year. This is your personal carbon footprint.

Now, write down your total carbon footprint

So, how did you do? If we add together what a "sustainable" carbon budget might be for the whole world, and then divide it by the global population, we get a figure of about one tonne (1,000kg) per person. Unless you live in a fossil fuel-eschewing eco-village in Somerset, there's every chance you'll be over this total at present and living a climatically unsustainable life. In fact, the national average for the UK is 9,400kg, about 10 times what would be sustainable for the planet. Still, we're not the worst, by any means: the average US carbon footprint is 19,800kg, while the impact on climate of the average Aussie is 18,000kg. Developing countries are far more sustainable: the average Chinese carbon footprint is 3,200kg, while the average Indian emits 1,200kg. Indeed, a good rule of thumb is that the poorer a person is, the less they emit - not a good omen in a world where everybody wants to be middle class. The average Tanzanian is highly sustainable, with a mere 100kg of carbon emissions per year, but it is unlikely that they are happy with this situation.

No lifestyle assessment would be complete without a spurious grading system, so here's one for your carbon footprint.

How you compare

A 1,000-3,000kg Either you're very green indeed, or you're lying. Hopefully it's the former.

B 3,000-6,000kg You're nearly there. Only a couple of tonnes to go.

C 6,000-9,000kg You're getting close to the national average. Could do better.

D 9,000-12,000kg You're an overconsumer. Sort it out now!

E 12,000-15,000kg You're a carbon criminal. Shouldn't you be reading the Daily Mail?

F 15,000-18,000kg You're Tony Blair (he came in at 17.9 tonnes). Do send our love to Cliff and Robin.

G 18,000-21,000kg You live like an American.

H 21,000+ You're Jeremy Clarkson. Shoot yourself now. For the planet.

· This article is based on Mark Lynas's book Carbon Counter, published by Collins and priced at £4.99. Got a question on your carbon footprint? Put your query to Mark Lynas here and you could win a copy of Carbon Counter.

Today's best video

Today in pictures