Listening to Sir Terry Leahy's speech last week on reducing carbon emissions, I pinched myself. A few years ago industry leaders ignored, dismissed or downplayed the urgency of the environmental case. Others just saw an opportunity to flog a few low-energy light bulbs. Good on Tesco for upping the stakes. But tensions lie ahead.

The strategy emphasises consumer choice when there shouldn't be one. We all have to reduce our carbon footprints. That's why Tesco's promise, like Marks & Spencer, to analyse products' carbon load is important, but it means some products will look carbon expensive.

This is all new managerial territory. Sir Terry et al have left their comfort zones. Toyota-style lean supply chain management hasn't internalised its environmental costs. In future, conventions about competition will change. We are talking planetary survival. Competition and 'green' image won't deliver necessary change fast enough.

If the entire trade must change, how can everyone come into line? Tesco's announcement, like Marks & Spencer's, let alone initiatives by pioneers such as Sainsbury's and the Co-op, suggests a 60-year era of value-for-money consumerism is waning. The new order is values-for-money. 'Leave it to consumers to decide' is rhetoric.

Supermarkets' carbon footprint isn't just in food but in buildings, trucks, m-ways, travel-to-shop, etc. Consumers must eat less meat and dairy. If serious food supply chain realignment is to happen, only governments can set the tougher frameworks needed. Businesses and politicians must accept that.

Heads are on the block. Listening to Sir Terry, I remembered other leaders announcing step changes - for instance, Lord Browne taking BP 'beyond petroleum' and Malcolm Walker turning Iceland organic. Lessons suggest retailers must together demand a new structure of government - nationally and at EU level. Going it alone is too risky.

Next month's International Panel on Climate Change report will highlight the importance of urgent action. At the Tesco launch, Lord May, former chief scientist, thanked campaigners for pushing big companies. The NGOs and think-tanks welcomed Tesco's move but urged businesses to move faster. They're right. Climate change is the environmental challenge, just as obesity is public health's. This journey is only just beginning.