Now [corporations] are looking at their supply chain as the next frontier for combating climate change. "Carbon footprint is absolutely new territory," said W. Drew Schramm, a senior vice president at the furnishings company Herman Miller and a member of the committee on social responsibility at the Institute for Supply, a trade group. "We're not sure how we'll measure it, we're not sure how we'll deal with it, but we've told our suppliers, 'Get ready, because we're going to ask you a lot of questions.' "

"If you are going to design carbon out of a product, you have to understand every place in the life cycle that carbon comes in," said Betsy Blaisdell, manager of environmental stewardship at Timberland.

"If you're going to make a real difference, you have to let go of your corporate ego," said Bonnie Nixon Gardiner, the global supply chain manager for social and environmental responsibility at Hewlett-Packard, which buys 53 billion dollars worth of products each year. "Many of us are operating in the same regions, with the same suppliers, even in the same factories, so our voice together is going to be much more powerful."