Wacky carbon footprinting challenges

Carbon footprinting is an alluring concept. Measuring the life-cycle carbon impact of a product or process in a simple and comparable unit provides priceless information to those seeking to limit their environmental impact.

But trying to make carbon footprinting a reality brings out some complex and even wacky problems. Questions like, 'how far down the supply chain do we measure?' and 'where does the life-cycle begin and end?' lead to difficult conceptual and technical questions.

Tesco has recently been coming face to face with these difficult issues. As a recent Guardian article explains, Tesco's "Dairy Centre of Excellence" has been fitting cows with "burp collars" to measure the methane (a highly damaging greenhouse gas) the cows produce on an hourly basis.This wacky concept is part of Tesco's plan to put carbon footprint labels on more than 130 products (milk being one of them).

As carbon footprinting efforts extend to other products and parts of the economy, there is no doubt that we will see ever more interesting and wacky things happening. These should be celebrated not scorned, however, because measuring carbon is an essential component of mitigating and reducing it.