Two million tonnes
BP has been telling us about climate change for some time and saying that talk stopped long ago. They have now started a new billboard campaign to tell us that they have helped offset Australian greenhouse gasses by two million tonnes. But what does it mean to offset emissions? Is two million tonnes of carbon offsets a lot? How does the average person evaluate a claim a like this?
Carbon offsets
A carbon offset is an investment in a project that reduces greenhouse gas emissions (e.g. an energy efficiency project) or sequesters carbon in the ground (e.g. reforestation).
Offsetting projects are assessed following the protocols established under the Greenhouse Gas Protocol Initiative. They can then be accredited under a variety of national and International schemes. For example, in Australia they can be reported and certified under the the Australian Government’s Greenhouse Friendly program, as BP has done.
Sometimes carbon offsets are referred to as carbon credits (credit for offsetting 1 tonne of greenhouse gasses). A carbon credit in the context of voluntary offsetting is not the same thing as a credit under an emissions trading scheme and the two are not exchangeable. We’ll talk more about Australia’s planned emission trading scheme (or carbon pollution reduction scheme as the government has started calling it) in a later post.
BP conducts a range offsetting projects under their Global Choice Brand. In Australia this primarily means offsetting the emissions associated with their staff vehicles.
Taking cars off the road
How much of current sea levels will be preserved by offsetting two million tonnes; how many endangered species will avoid extinction; how many violent storms will be stopped?
The Australian government publishes information on the impacts of climate change. However we can’t really relate individual offsetting back to these kinds of real-world impacts.
To help people evaluate the the benefit of offsetting two million tonnes BP have related their offsetting back to cars. They say:
Seven years after launch, our BP Global Choice™ programme had made a reduction in greenhouse gas equivalent to taking over 400,000 cars off the road.
This is an analogy, BP haven’t necessarily taken any cars off the road. Instead they have invested in projects that have offset an amount of emissions equivalent to the emissions produced by a certain amount of car travel.
An average car traveling 25,000Km in a year will produce about five tonnes of greenhouse gasses. This gives us the figure of 400,000 cars (two million divided by five). Having done this calculation we do need to modify BP’s claim a little: “Seven years after launch, our BP Global Choice programme had made a reduction in greenhouse gas equivalent to taking over 400,000 cars off the road [for one year, or 60,000 cars a year for seven years].”
While the concept of a car is more concrete than a tonne of carbon emissions it is still difficult to evaluate a number like 400,000 without some perspective. According to Australian Bureau of Statistics there are about 14 million registered cars and light passenger vehicles in Australia.
Australia’s overall emissions
Another way to assess two million tonnes of offsetting is to put it in the context of Australia’s overall emissions. In the Kyoto Period of 2008 to 2012, Australia’s emissions are forecast to be about 600 million tonnes per year.
That’s about 70,000 tonnes an hour. So two million tonnes of offsetting is equivalent to about 28 hours of Australia’s overall emissions.
Another comparison is with Australia’s per capita emissions, which is about 28 tonnes per person per year. Based on this figure two million tonnes of offsetting is equivalent to the emissions for 70,000 people for a year: somewhere between the population of Bunbury and Ballarat.
The cost of offsetting
Finally we might assess an offsetting initiative in cost terms. Depending on the cost of the offsetting project and the quality of the outcome and the accreditation, offsets typically cost between AU$10 and AU$30 per tonne.
On this basis offsetting two million tonnes might cost between AU$200M and AU$600M: now that’s definitely a big number.
