This conclusion is derived from an interesting article called “The mpg confusion” (mpg=miles per gallon) featured on RealClimate – Climate science from climate scientists:
http://www.realclimate.org/index.php/archives/2008/09/the-mpg-confusion
The article caused an exciting discussion (over 340 responses), pointing out that a product’s whole lifecycle has to be considered to evaluate its environmental impact.
October 15, 2008 at 5:58 pm
Although a general point – it is not always that obvious. I would like to see people’s views or practical experiences on this topic.
October 22, 2008 at 11:54 am
Well, I guess the main issue is problems of measurement. Even if you only look at embedded greenhouse gas emissions (and ignore other environmental impact for now) it is really hard to calculate the emissions that got embedded in a product during its production.
In the UK attempts have been made (I think by Tesco) to put the embedded emissions on the packages of certain products. This turned out to be quite a difficult task even with ordinary items such as potatoe chips. Obviously, the emissions from the farming of the potatoes (fertiliser, fuel for tractors etc) and processing (electricity for “chips chopping” machines) would have to be accounted for as well as transport from farm to factory to store and the electricity consumed in the stores. But what about the less obvious things? Clearly, the tractor used for farming has its own embedded emissions from the mining and transport of the iron ore to the extraction and processing of the oil for the tires. And the same is true for the factory building and the machines which process the potatoes into chips, and of course the store etc.
So clearly, if it’s that hard to calculate embedded emissions for crisps, it would be much harder for a car with hundreds of sub-contractors and parts etc.
So I guess, at the core of the issue is the question, which measures give reasonable information to buyers who want to reduce their impact (e.g. mpg) but are at the same time easy to calculate and understand.
On the downside, too simple measures inevitably also neglect potentially important factors. This became clear in the footmiles discussion in the UK when a easy-to-understand number (miles that food travelled from farm to consumer) was overemphasised over total emissions and subsequently people stopped buying fruit that had been flown in from, say, Kenya, in favour of fruit that had been grown in heated greenhouses in Britain – with much more embedded energy than the Kenyan ones.
October 28, 2008 at 8:36 pm
Thank you for clearly outlining how difficult it is to measure the CO2 emissions, let alone all greenhouse gases. I remembered hearing about Tomatoes grown in England having a higher CO2 footprint than the ones coming from Spain – quick google search resulted in a Guardian article:
“For example, fruit and vegetables trucked in from Spain could actually have a lower carbon footprint than those grown in UK greenhouses which use up lots of energy for heating.”
(http://www.guardian.co.uk/environment/2007/jun/07/food.foodanddrink)
The following links briefly introduce an initiative in Germany of nine businesses to measure the emissions of CO2 and other greenhouse gases related to selected products and services. The project currently discusses the methodology of how to measure the emissions together with existing international initiatives. The outcomes are expected for the end of this year…
http://www.oeko.de/press_room/press_releases/dok/804.php
http://www.thema1.de/pcf_PM_eng.pdf