How do you know that concern about climate change has reached the mainstream? When a product's carbon footprint is a factor in every buying decision.

And how do you know the carbon footprint of a product? Through eco-labeling - a label disclosing the amount of energy used to produce the product, or the amount of CO₂ that producing the product released into the atmosphere. The idea is similar to nutrition labeling - give consumers the knowledge they need to make informed choices.

Eco-labeling is springing up all over the place:

• In January, the British supermarket chain Tesco announced it will label its 50,000 Tesco-branded food and clothing products with a carbon footprint measure. Impressive - especially since it will cost the company almost $1 billion.
• Timberland labels its shoes with "Our Footprint", which includes the amount of energy, in kilowatt hours, used to produce the pair of shoes.
• Last week Wal-Mart announced that it will score its electronic products on environmental sustainability.
• Also last week, the U.K. company Carbon Trust announced the launch of a Carbon Reduction Label. The label will show the greenhouse gases released in the manufacture, transportation, and disposal of consumer goods.
• Yahoo's Green Car Center provides a "Green Rating" for new automobiles.

You can find more examples at Eco-Labels, the Consumers Union Guide to Environmental Labels.

While eco-labels are a great idea, there are two problems. Carbon footprints are complicated to assess, and without standardization and evaluation by a third party there's no way to know their accuracy. Also, without an industry-wide standard measure, you don't know whether a particular carbon footprint is good or bad - how it compares to other products in the same category. Still, you have to start somewhere and this is a good start!