Growing public concern about climate change has prompted several of the leading supermarket chains to announce major new environmental initiatives in the past 18 months.
Asda has made a string of announcement on issues such as sustainable fish, packaging and waste management since parent company Wal-Mart fought back against its critics and announced a raft of environmental targets (ENDS Report 375, pp 28-31 
).
More recently Marks & Spencer sought to "differentiate its brand" by outlining comprehensive plans to become carbon-neutral, reduce food miles by sourcing more food locally and extend sustainable sourcing (ENDS Report 384, pp 5-6 ).
Tesco’s strategy is to focus on the one issue dominating the environmental agenda: climate change. Last year it announced plans to cut energy use in its buildings and invest £100 million in low-carbon technologies (ENDS Report 376, p 4 ).
Its new plans for a carbon labelling scheme, revealed in a speech by chief executive Sir Terry Leahy in January, won praise from environmental groups.
"Tesco’s commitment to count and display the carbon cost of every product is groundbreaking," said Forum for the Future chief executive Peter Madden. "When you have a company as powerful as Tesco and a boss as influential as Terry Leahy giving serious attention to climate change, the rest of business has to listen."
Greenpeace UK director John Sauven described the promised labelling scheme as "a major step forward" but said Tesco should also take particularly climate-damaging products, such as conventional light bulbs, off the shelves.
In his speech Sir Terry said the environmental, social and economic consequences of climate change will be "stark and severe" if society fails to act and that Tesco’s size and reach gave it a "particular responsibility".
Moreover, like recycling household waste, buying low-carbon products has acquired a feel-good factor. "The market is ready. Customers tell us they want our help to do more in the fight against climate change if only we can make it easier and more affordable."
When the first wave of green marketing and product labelling arose in the late 1980s, consumers were quickly turned off by spurious and misleading claims. But today, retailers accept that the demand is there if the information is clear.
"The huge growth in sales of organic food is testimony to the fact that people will make greener choices if we give them the right information, opportunity and incentive," said Sir Terry.
Customers, he continued, want Tesco to "develop ways to take complicated carbon calculations and present them simply. We will therefore begin the search for a universally accepted and commonly understood measure of the carbon footprint of every product we sell - looking at its complete life cycle from production, through distribution to consumption."
Tesco refused to discuss any of the points made in Sir Terry’s speech. While undoubtedly a bold move, calculating the carbon footprint of the many thousands of different products Tesco sells - some of which have complicated supply chains or highly variable use profiles - will be a gargantuan and controversial undertaking that will need the support of many different stakeholders to be credible.
There is also the danger that some products will be labelled as "low-carbon" and be perceived as environmentally friendly when they are associated with other serious environmental impacts such as use of hazardous substances or inefficient water use.
As a first step towards the labelling scheme, Tesco has commissioned work from Oxford University’s Environmental Change Institute on "identifying and overcoming" the carbon pressure points in its own operations and supply chain. It hopes to involve its suppliers and distributors and other retailers and has also begun to work with Unilever.
As an interim step, Tesco will put an aeroplane symbol on all air-freighted products in its stores and restrict its reliance on air transport to less than 1% of its products. The company refused to say what the current proportion is, but it is likely to be less than 5%. Marks & Spencer is also planning to adopt the aeroplane symbol, said Sir Terry.
Tesco must "face up" to the food miles debate, he said, and accept that "transporting a product by air results in far higher carbon emissions than any other form of transport."
Less impressively, Sir Terry sought credit for promising to measure, publish and reduce the company’s greenhouse gas emissions. Sainsbury’s already publishes data on its annual CO2 emissions and all supermarkets will have to submit such data to the government if the UK’s new emissions trading scheme for large commercial and public sector organisations, the Energy Performance Commitment, is established (ENDS Report 382, pp 38-39 ).
Tesco achieved an absolute reduction in the energy use of its buildings "this year" and expects to meet its target to halve their average energy use from a 2000 baseline two years early in 2008.
The company is also targeting refrigeration, which accounts for over a third of Tesco’s direct carbon footprint in the UK of about 2 million tonnes of CO2. In comparison, Tesco’s transport fleet accounts for less than a sixth.
Most Tesco refrigeration systems, like most others used by supermarkets, use the potent greenhouse gas HFC-134a as the refrigerant (see pp 32-33 ). The supermarket says it is "leading" a programme to phase out their use - but does not give a deadline.
Tesco has also promised to halve the price of energy-efficient light bulbs and work with the Energy Saving Trust to develop "stronger energy efficiency labelling" for electrical products.
It will also promote energy-efficient products through its green clubcard scheme. Tesco is one of 11 retailers that has been discussing a voluntary agreement with the government that would promote such products (ENDS Report 378, p 22 ).