Exhaust rises from the main chimneys of a coal-fired power plant.
Exhaust rises from the main chimneys of a coal-fired power plant. - 


Scott Jagow: Environmentalists are trying to fine tune the measurement of companies' carbon emissions, and they've started looking at the supply chains of big companies. Nancy Marshall Genzer has more.

Nancy Marshall Genzer: Right now, a company like Dell just measures the carbon it emits. A group called the Carbon Disclosure Project has signed up a dozen big name corporations, including Dell and Procter and Gamble, for an experiment.

Project head Paul Simpson says suppliers fill out a carbon emissions questionnaire. When their emissions are added, a corporation's carbon footprint goes up a shoe size or two.

Paul Simpson: Companies need to understand where in the world they have ownership or an influence over emissions.

But Scott Segal, an environmental lawyer representing utilities, say emissions are hard to measure.

Scott Segal: There's an awful lot of what I would call voodoo economics that's associated with determining the carbon footprint of any one particular industrial process or any one particular facility.

The Carbon Disclosure Project says this experiment will help solve that problem by creating a single, standardized approach for measuring the emissions of a corporation and its suppliers.

In Washington, I'm Nancy Marshall Genzer for Marketplace.