Sky's the limit?

January 2007

Our carbon footprints are catching the attention of the media and politicians, but what are they exactly and why the worry?

As average incomes rise, more and more people in Britain can afford to take air flights. We are also consuming growing amounts of food and goods that are flown or shipped here from far-away places.

The same is happening in other countries, not just in MEDCs but emerging economies like China and India also. As a result of these changes in consumer behaviour, transport is now the fastest growing source of emissions of carbon dioxide – the gas that is most responsible for climate change.

So are even greater emissions of carbon dioxide (CO2) now inevitable year-on-year? This article examines how “carbon footprints” are measured and assesses strategies that might be used to reduce them.

In the Members' Area:

• What is a “carbon footprint”?

• How big is your carbon footprint?

• Is it OK to keep flying?

• What are “food miles” and why do they matter?

• What can we do to reduce our carbon footprints?

• KS3/4 suggestions for teachers

What is a carbon footprint?

Many of us will already be familiar with the term ecological footprint. It is a measurement of the area of land or water required to support a person (or society) at their usual standard of living. It is the room needed to provide that person with the energy, food and resources they need to live and to also absorb their wastes. For someone in the UK, it is about the size of six football pitches (the global average is one third of this).

Carbon footprint is a similar measure, but one that describes the amount of carbon dioxide used by an individual or organisation as they go about their everyday lives or operations. It is usually measured in terms of the volume (tons) of carbon dioxide emitted into the atmosphere as a result of fossil fuels being used to provide energy for homes, personal transport and the manufacture and transport of goods for personal consumption. In the UK, each person produces, on average, 11 tons of carbon a year whereas in the US the figure is 19 tons (The Independent, 09 December 2006).

Carbon dioxide is what allows the earth’s greenhouse effect to operate, trapping the sun’s energy in the atmosphere and sustaining life on earth. However, too much can cause over-heating and levels are now possibly the highest they have been for at least 10 million years. They have been rising steeply ever since the industrial revolution in the Eighteenth Century when fossil fuel energy use really began to take off. Ever since then, the carbon footprint of people living in economically developed societies has been growing steadily larger and larger.

Scientists believe that levels will rise further still as global industrialisation drives energy use even higher, most likely heating the atmosphere to dangerous levels. It is therefore in everyone’s interest to start thinking about ways to reduce their own personal carbon footprint

How big is your carbon footprint?

The Independent (09 December 2006) reports that new research has been published that calculates a carbon footprint for the average British citizen. A study by the government-funded Carbon Trust puts the annual carbon footprint of the average Briton at 10.92 tons of CO2 - roughly half of the 19 tons of CO2 produced each year by the average American.

Table 1 below shows how the total can be broken down into different activities.

Table 1: Average UK carbon emissions (per person per year)
Source: adapted from The Independent, 09 December 2006

Recreation 1.95 tons
The single largest source of emissions of CO2 is leisure activities (plus the manufacture and production of goods and services). Major examples include seaside trips (which create 200 kg per person each year) and TVs, videos and stereos (another 35 kg).

Heating 1.49 tons
The second biggest source of CO2 results from the burning of gas, electricity and oil. Every extra degree on a thermostat accounts for an additional 25 kg of CO2 per person per year.

Food 1.39 tons
Plenty of carbon dioxide is generated by energy used in cooking, eating and drinking - including “food miles” and the production of raw materials (for instance in heated greenhouses). This figure includes food transport in UK - equivalent to 300 kg per person a year - and driving to supermarkets - another 40 kg. A restaurant meal generates 8 kg per diner.

Household 1.37 tons
This category consists of non-heating emissions generated in the home from electrical appliances, the manufacture of furnishings and from the construction of the building itself. A fridge is responsible for 140 kg of carbon annually, while lighting in a house contributes a further 100 kg – an interesting contrast!

Hygiene 1.34 tons
The carbon cost of keeping clean: it includes emissions from the NHS and from individuals bathing and washing. Taking baths instead of showering adds 50 kg a year to carbon production.

Clothing 1.00 tons
Emissions are generated in producing, transporting and cleaning clothes and shoes. In a year, the average person will expend 70 kg of energy on new clothes, 100 kg by using washing machines and 36 kg by using tumble dryers.

Commuting 0.81 tons
Carbon is emitted as adults travel each day to and from their workplace (using either public or private transport). Assuming a journey of three miles undertaken five times a week, the use of a car represents 500 kg of energy for the average commuter in a year.

Aviation 0.68 tons
Although not yet the greatest contributor, this is the fastest growing source of CO2 emissions - which is why there is so much debate over whether taxes on flights should be increased (to slow the rate of increase). A return flight to Malaga, for example, would represent 400 kg of energy per passenger. A short break to Prague would expend 220 kg of energy.

Education 0.49 tons
These are emissions relating to the running of school buildings, travel to and from school and the manufacture of books. For instance, a large vehicle school run adds 200 kg per person per year.

Phones 0.1 tons
Finally, a small but significant amount of CO2 emanates from the energy used to drive communications including computing. Mobile phone chargers, for example, account for between 35 and 70 kg per person per year.

Perhaps the most surprising finding is just how much of a contribution recreation makes, with The Independent noting that “activities as diverse as watching a football match or taking a trip to the seaside - account for most of our emissions, rather than a lack of insulation or a predilection for 4x4 cars”.

How does your own lifestyle compare with the average UK person? Look at each of the categories and think about whether you probably produce more or less carbon than most other people. Does that make your overall footprint larger or smaller than average?

Christmas carbon footprint

According to The Times (20 November 2006), “Christmas lunch will fly 84,000 miles to your door”. What this actually means is that the basic ingredients that make up the average person’s festive lunch will have collectively clocked up an amazing 84,612 miles (to be precise) while being transported by planes, lorries or ships. Some imports are easy to identify, such as green beans from Kenya or wine from New Zealand. Harder to spot are individual ingredients used in stuffing or mincemeat that may have come from far-flung places.

All of this means that, here in the UK, our carbon footprint will have been even bigger on Christmas Day than usual - especially for people who took internal air flights to visit family. Aeroplane emissions of carbon dioxide are increasingly seen as one of the most serious threats to the planet, given (i) the speed at which they are increasing and (ii) the disproportionate impact on climate change that they have in relation to the small (but growing) percentage of the world’s population that can afford to use them.

Source: The Times, 20 November 2006

Investigating the festive carbon footprint

Frozen turkeys flown into the UK from Thailand
The cargo plane emits 1,721kg CO2

Organic free-range goose driven to London from Norwich 
A journey like this would produce only 9kg CO2

Wine flown into the UK from New Zealand 
The flight generates 3,302kg CO2

Wine from Chapel Down Flint in Kent 
Driving a van of wine to London generates only 5kg CO2

Runner beans flown into the UK from Zambia 
The flight emits 2,011kg CO2

Sprouts driven from Kent to London 
The lorry ride generates only 5kg CO2

Is it OK to fly?

The challenge

Estimates vary as to the total contribution that air flights already make to global warming, ranging from around 4 to 10%. Figures differ because it is not just the carbon emissions from aeroplanes that are thought to be heating the atmosphere. There is also a “radiation forcing effect” that takes place in the upper troposphere, where vapour trails produce ice crystals that trap additional heat.

Whatever the correct figure may be, one thing is sure: it is set to rise upwards. Recent years have seen massive growth in the numbers of people taking short-haul air flights. In the UK, demand is growing at 5% a year on average while prices are falling, making it easier for more people to fly. For instance, earlier this year BA announced that it was slashing prices from London to almost all European destinations in order to compete with the success of low-cost airlines such as Ryanair and easyJet (The Guardian, 20 April 2006).

However, air flight growth is not just restricted to the richest nations. The emerging economies of India and China are witnessing annual growth rates of around 15%. For instance, India is currently spending $12 billion on airport building and has 330 new aircraft on order (its current civil fleet numbers just 200). India's minister for aviation predicts that up to 2,000 planes could be operating by 2020 (The Guardian, 20 May 2006).

The debate

There are many differing viewpoints in the new debate over whether flying “is OK”. Is it actually as damaging as some people say? What, if anything, can and should be done to limit its effects, given that air flight also helps drive economic growth? Here are some of the different points of view generally on offer in the UK media – students may wish to discuss their relative merits.

(1) “There are worse offenders than the air industry”

Some other activities are far more damaging to the environment - road transport accounts for 21.3% of CO2 emissions, for instance. Why, asks the air industry, do environmentalists keep criticising? However, although it may not yet be the biggest polluter, air transport is growing at the fastest rate.

Flights to and from UK airports are expected by the government to double by 2030. Aviation emissions will most likely quadruple by 2050 (New Statesman, 03 April 2006). A recent report from Oxford University suggested this would mean that the contribution aviation makes to UK emissions would rise from 5.5% to 25% (The Guardian, 14 November 2006).

(2) “Reducing flights would damage the economy”

Three years ago, a government report estimated that a new 2 km runway at Heathrow would bring nearly £8 billion to the UK economy, as flights would increase from 470,000 to 700,000. As well as Heathrow’s planned third runway, twelve other UK airports, including Aberdeen, Edinburgh, Southampton, Norwich and Swansea, are planning large-scale expansions.

Six, including Stansted, Edinburgh, Glasgow and possibly Gatwick, may almost double in size with new runways. Economists back such proposals as they will all certainly be profitable initiatives (The Guardian, 14 November 2006). But can the UK government truly reconcile its loyalty to the airline industry with its supposed commitment to sustainability? (The Guardian, 28 February 2006)

(3) “Trading emissions will solve the problem”

A full international carbon trading scheme might “give the private sector the incentives it needs to come up with energy-efficient planes and cleaner fuel” (The Guardian, 25 November 2006). Already in existence, the European Union Emission Trading Scheme commenced operation in January 2005 and 25 member states of the EU already participate in the scheme.

Critics argue that emissions trading – a finacial agreement between nations where some countries can continue to pollute greatly as long as others do not – still does not solve pollution problems overall. Significant overall reductions in total carbon emissions would need to come from a reduction of permits available in the system and ultimately a goal of zero emissions.

(4) “Building better planes could solve the problem”

The new Airbus A380 has the lowest fuel consumption per passenger of any large commercial airliner yet built. It requires less than three litres of fuel per passenger per 100 km travelled, making it more fuel-efficient than even the latest hybrid cars.

However, critics point out that any likely emissions reductions will be quickly swamped by the increase in total flight numbers. And although even greater technical changes are surely possible, do we have enough time left to invent them? Perhaps the thought of a hi-tech fix remains a distant aspiration, rather than an immediate solution.

(5) “Using different fuels could reduce pollution”

Might it be possible to burn hydrogen instead of fossil fuels? Critics say that although such a transition may be possible in the future, it is unlikely to provide a “technological fix" quickly enough – and we need one urgently!

There are other issues to consider too – hydrogen fuel produces a combustion output of water which, when injected high in the stratosphere, would contribute to global warming rather than reducing it (the “radiation forcing effect”). There are similar doubts over possible greater future use of biofuels.

(6) “Planting more trees will solve the problem”

Firms such as the UK’s Carbon Neutral Company offer individuals and organisations the chance to erase the environmental damage caused by their greenhouse gas emissions. Trees soak up carbon dioxide, the thinking goes, so planting a new tree can neutralise some of the carbon produced by flying in a plane (The Guardian, 07 October 2007).

However, this is a delaying tactic rather than a solution. And if we do have a 2C or 3C temperature rise, then some of these trees may die early in any case. Scientific doubts over the value of carbon credits from forest projects led to their exclusion from the EU Emission Trading Scheme.

(7) “Taxing flights will reduce the number of planes in the air”

If flight prices were increased, through taxation or airlines raising ticket costs, then there would be fewer planes in the air. However, critics of this approach say that it would stop the poor from flying, making it the exclusive preserve of the rich once again - which would be unfair. But what is more important: social justice or survival of the planet?

Writing in The Guardian (20 May 2006), Leo Hickman argues that “I simply don't buy the argument put forward by the airlines that this is undemocratic because it will make flying an elitist activity once again. Most of the evidence shows that the majority of new demand in the UK is simply the same people flying more.”

(8) “Stopping flying is the only solution”

A recent article in New Statesman (03 April 2006) suggests that “in this dreadful, dark picture there is one glimmer of hope. A no-flying movement is beginning to take shape, with many people voluntarily committing not to fly at all for non-essential trips. It is already a sufficiently large market to be taken seriously by the newspaper travel supplements, which are starting to provide information on train or shipping alternatives.

“And there are benefits. Travel to the Alps by train and you get a real sense of geography, of evolving culture and changing climatic zones. Arrive by air and all you see is identikit airport terminals and thousands of other culture-shocked, aggravated travellers. Slow travel, like slow food, is about clawing back quality of life.”

What are food miles and why do they matter?

Introducing the issue

Over the last fifty years, there have been dramatic changes in food production techniques and in the length of supply chains for the UK’s major supermarkets. According to a recent report by DEFRA, the most striking developments have been:

• Globalisation of the food industry, with wider sourcing of food both within the UK and from overseas.

• Changes in the source of food supply in order to meet demand for year-round supply of produce such as fruit and vegetables.

• Major changes in delivery patterns with most goods now routed through supermarket regional distribution centres, and a trend towards use of larger Heavy Goods Vehicles (HGVs).

• Centralisation and concentration of sales in supermarkets and hypermarkets, with a switch from frequent food shopping (on foot) at small local shops to weekly shopping by car at large out of town supermarkets.

Food mile facts

These trends have led to a large increase in the distance food travels from the farm to consumer, known as food miles. Some food mile facts described in the recent DEFRA report include:

• Since 1978, the annual amount of food moved in the UK by HGVs has increased by 23%, and the average distance for each trip has increased by over 50%.

• Food transport to supply UK consumers produced 19 million tonnes of carbon dioxide in 2002, of which 10 million tonnes were emitted in the UK, representing 1.8% of the total annual UK CO2 emissions, and 8.7% of the total emissions of the UK road sector.

• Transport of food by air has the highest CO2 emissions per tonne, and is the fastest growing mode. Although air freight of food accounts for only 1% of travel distances (in tonnage) it is responsible for 11% of the food transport CO2 emissions!

What can be done?

Many people want to help reduce carbon emissions by buying British food and avoiding imported foods. Unfortunately, the situation is more complex than it at first appears to be. Locally produced food can actually end up travelling long distances if it is taken to central depots for storage before being delivered to retail outlets. The DEFRA report suggests that people who are trying to shop ethically need to ask a few other important questions as well:

(1) Was the transport efficient? Large aeroplanes and HGVs may travel long distances but they are also efficiently loaded vehicles which reduces the impact per tonne of food. Locally-sourced food may have travelled shorter distances but often in much smaller vehicles, meaning that CO2 emissions per tonne are relatively high!

(2) How much energy did the food production system use? A case study showed that it can be more sustainable (at least in energy efficiency terms) to import tomatoes from Spain than to produce them in heated greenhouses in the UK outside the summer months.

(3) What are the social benefits of buying overseas food? Many developing nations are dependent on food exports to countries such as the UK. Will it hurt Kenyan farmers if UK consumers stop buying Kenyan runner beans because of the high food miles attached to them?

Clearly, a number of other issues are bound up in the food miles debate - which is, in turn, part of a much wider set of concerns about both globalisation and climate change.

Transport and trade of food has the potential to lead to economic and social benefits, both for developed and developing nations (the latter of whose economic sustainability may well depend upon continued exporting).

However, the increasing use of far-away produce and growing reliance on air freight are hardly environmentally sustainable practices. For people who are concerned with “doing the right thing” this is a very difficult area of personal decision-making – with no easy answers!

What can we do to reduce our carbon footprints?

The Independent newspaper (09 December 2006) poses a series of questions which geography students can use as a starting point for discussing: what can we do to help?

• How much emitted CO2 is embedded in your crisps, that is, how much was involved in making them? How much in that instant chicken tikka you're having for dinner, or that sofa you covet, or those new trainers you want to buy? Do you ever think about these things?

• When, as a careful consumer, you read the label on a packet of crisps, what do you look for? How much salt it contains? How many additives, E-numbers, artificial colouring or preservatives? Perhaps you look for all of those.

• But consider this. What if the label also told you how much carbon dioxide had been emitted in its manufacture? What if it informed you just what part in causing global warming had been played by the process of putting this snack in your hand? And furthermore, what if a comparison of labels showed you that X Crisps were responsible for fewer emissions of CO2 than Y Crisps? Would it not affect your buying decision - and would not X Crisps get your vote?

11-16 curriculum

Back in October, The Guardian published a graphic showing the size of different ecological footprints for different nations and continents, using data from a new World Wildlife Fund report. These figures could easily be used to prepare a set of different sizes of cardboard feet (or circles if you art skills aren’t up to it!) which are proportionally sized. Working in groups, children can try and match the size of feet with the name of the country...

Ecological Footprint Diagram Guardian 25 October 2006

The associated article: Collapse of ecosystems likely if plunder continues Guardian 25 October 2006

Written by Dr Simon Oakes, a Principal Examiner for Edexcel and Sixth Form teacher at Bancroft’s School.