Wednesday, December 13, 2006

Carbon or Carbon dioxide?

Apparently the UK emits 2% of the world’s CO2 or 150 million tonnes. I was confused when I saw an advertisement from the Carbon Trust talking about 648 million tonnes, so I phoned them up and then sent the following email.

“Your advertisement in today's Independent talks about annual CO2 emissions of 648m tonnes, while the DTI report "The Energy Challenge" quotes 150m tonnes. One of your customer advisors pointed out that your figure is for CO2 but the DTI figure is the carbon component only. If we take the atomic weight of carbon at 12 and oxygen at 16,carbon accounts for 12/44 of the weight of CO2, or 27%.

"Dividing 150 by 27% gives 550, not 650. Is your figure for CO2, or have you included other greenhouse gases as well? I'm about to publish a book on this, so I need to know the right answer!”

Here’s their reply:

“Dear Mr. Day,

"The figures cover carbon emissions from fuel use and so do not include carbon emissions from other processes or emissions of other greenhouse gases.

"The figure of 648 million tonnes of carbon dioxide (equivalent to 176.4 million tonnes of carbon) is the total UK carbon emission consumption.
This is different from the UK carbon emission production. Our figures differ from the 2002 UK Production Footprint, produced by Defra in 3 key
* Ours includes aviation fuel use;
* We use slightly higher water transport figures; and
* Our report talks about UK consumption and so includes carbon
emissions from products produced overseas and brought to the UK for consumption (e.g. Chinese T-shirts and German cars). For consistency, our figure excludes emissions from products and services which are produced in the UK but which are then sent overseas for consumption (e.g. Scotch Whisky sent to the Far East). The UK is a net importer of products and services and so our consumption footprint is higher than our production footprint as a consequence.

"There is a breakdown of these differences on page 22 of our report 'The carbon emissions generated in all that we consume', which is available from the Carbon Trust website at this link.

"Note: The figures presented in this report are in terms of carbon not carbon dioxide.”

A clear and comprehensive answer. So now we know!

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