They have also agreed to come up with clear definitions of oft-used terms such as 'carbon neutral' and 'sustainably sourced' so that consumers can have confidence that when these phrases are bandied around, they actually mean something, said Tesco boss Sir Terry Leahy.
Sharing a podium with Unilever chief executive Paul Polman at the global summit of the Consumer Goods Forum in London this week, Leahy said: "We need to draw up a common language [around green issues] so that one supplier's definition [of a term such as carbon neutral] cannot be different to another supplier's definition."
Sharing information would also help drive the implementation of carbon footprint labelling more quickly, he said: "But we also want to go much further than this and develop a common global system for measuring the greenhouse gases in the lifecycles of the products and services we sell. This work could be extended over time to cover other sustainability challenges, but should begin with greenhouse gases.
"The prize in time could be a single open-source repository for this data, shared across our industry."
Members of the Consumer Goods Forum had also agreed to look more closely at refrigerants and deforestation, "two specific hotspots in the supply chain", added Polman.
"The aim is to persuade our member companies to work together to put an end to deforestation. Whether we like it or not, it's our industries that are providing the incentive for people to chop down trees."
Given its size, Unilever had a particular responsibility to lead the way on green issues, accepted Polman. "Our brands are in nine out of 10 households on the planet. Few governments serve as many people as those of us here in the audience today, so surely we do have a responsibility."
To those arguing that green initiatives should be put on hold until the economy emerges from recession, added Polman, "I would say no."
Carrot not stick
Critically, firms such as Tesco had to prompt a "quiet revolution in people's lives" by incentivising consumers to buy products with a lower environmental footprint and rewarding good behaviour rather than punishing bad behaviour, said Leahy.
"Too often the green option remains the expensive option. Remove the price barrier and then people will respond. We want to make low carbon products the most attractive and easiest choice. Give people a small reward or thank you rather than a charge or penalty and they will respond positively."