There is one interesting claim, namely that future carbon emissions have a value which differs to current emissions. This claim is true because of economist's habit of discounting future impacts and the fact that in the future the stock of carbon emissions will be greater and hence the marginal damage will differ.
Rejoice! We have a way out. Our guilty consciences appeased, we can continue to fill up our SUVs and fly around the world without the least concern about our impact on the planet. How has this magic been arranged? By something called "carbon offsets". You buy yourself a clean conscience by paying someone else to undo the harm you are causing.
This week, the Co-op's holiday firm Travelcare started selling offsets to its customers. If they want to fly to Spain, they pay an extra £3. Then they can forget about their contribution to climate change. The money will be spent on projects in the developing world, such as building wind farms and more efficient cooking stoves. In August, BP launched its "target neutral" scheme, enabling customers to "neutralise the CO2 emissions caused by their driving". The consequences of an entire year's motoring can be discharged for just £20. Again, your money will be invested in the developing world - "a biomass energy plant in Himachal Pradesh; a wind farm in Karnataka, India, and an animal waste management and methane capture program in Mexico" - and you need have no further worries about what you and BP are doing to the atmosphere (or, for that matter to the tundra in Alaska).
It sounds great. Without requiring any social or political change, and at a tiny cost to the consumer, the problem of climate change is solved. Having handed over a few quid, we can all sleep easy again.
This is not the first time such schemes have been sold. In his book The Rise of the Dutch Republic, published in 1855, John Lothrop Motley describes the means by which the people of the Netherlands in the 15th and 16th centuries could redeem their sins. "The sale of absolutions was the source of large fortunes to the priests ... God's pardon for crimes already committed, or about to be committed, was advertised according to a graduated tariff. Thus, poisoning, for example, was absolved for 11 ducats, six livres tournois. Absolution for incest was afforded at 36 livres, three ducats. Perjury came to seven livres and three carlines. Pardon for murder, if not by poison, was cheaper. Even a parricide could buy forgiveness at God's tribunal at one ducat; four livres, eight carlines."
Just as in the 15th and 16th centuries you could sleep with your sister and kill and lie without fear of eternal damnation, today you can live exactly as you please as long as you give your ducats to one of the companies selling indulgences. It is pernicious and destructive nonsense.
The problem is this. If runaway climate change is not to trigger the irreversible melting of the Greenland and West Antarctic ice sheets and drive hundreds of millions of people from their homes, the global temperature rise must be confined to 2C above pre-industrial levels.
As the figures I have published in my book Heat show, this requires a 60% cut in global climate emissions by 2030, which means a 90% cut in the rich world. Even if, through carbon offset schemes carried out in developing countries, every poor nation on the planet became carbon-free, we would still have to cut most of the carbon we produce at home. Buying and selling carbon offsets is like pushing the food around on your plate to create the impression that you have eaten it.
Any scheme that persuades us we can carry on polluting delays the point at which we grasp the nettle of climate change and accept that our lives have to change. But we cannot afford to delay. The big cuts have to be made now, and the longer we leave it, the harder it will be to prevent runaway climate change from taking place. By selling us a clean conscience, the offset companies are undermining the necessary political battle to tackle climate change at home. They are telling us we don't need to be citizens; we need only to be better consumers.
BP and Travelcare, like other companies, want to keep expanding their business. Offset schemes allow them to do so while asserting they have gone green. Yet aviation emissions, to give one example, are rising so fast in the UK that before 2020 they will account for the country's entire sustainable carbon allocation. A couple of decades after that, global aircraft emissions will match the sustainable carbon level for all economic sectors, across the entire planet. Perhaps the carbon offset companies will then start schemes on Mars, as we will soon need several planets to absorb the carbon dioxide we release. Offsets, then, are being used as an excuse for the unsustainable growth of carbon-intensive activities.
But these are not the only problems. A tonne of carbon saved today is far more valuable in terms of preventing climate change than a tonne of carbon saved in three years' time. Almost all the carbon offset schemes take time to recoup the emissions we release today. As far as I can discover, none of the companies that sell them uses discount rates for its carbon savings (which would reflect the difference in value between the present and the future). This means they could all be accused of unintentional but systemic false accounting.
And while the carbon we release by flying or driving is certain and verifiable, the carbon absorbed by offset projects is less attestable. Many will succeed, and continue to function over the necessary period. Others will fail, especially the disastrous forays into tree planting that some companies have made. To claim a carbon saving, you also need to demonstrate that these projects would not have happened without you - that Mexico would not have decided to capture the methane from its pig farms, or that people in India would not have bought new stoves of their own accord. In other words, you must look into a counterfactual future. I have yet to meet someone from a carbon offset company who possesses supernatural powers.
At the offices of Travelcare and the forecourts owned by BP, you can now buy complacency, political apathy and self-satisfaction. But you cannot buy the survival of the planet.