Earlier this year Walmart circulated a questionnaire to suppliers requesting details on carbon footprint data. Their intention, according to the accompanying explanatory note, was to collect data which eventually would be presented as a numerical declaration at point of sale or on packaging, to guide purchases by consumers.

The October 23rd edition of New York Times contained an interesting review of the situation in Sweden authored by Elizabeth Rosenthal a well-respected writer on scientific and medical topics. The nation of Sweden, often at the forefront of progressive trends in ecology, sociology and public health, has undertaken to reduce greenhouse gas emissions in all areas including transport and food production.

While we are still debating cap and trade and the fuel consumption limits for our automobiles, Sweden has drawn plans to eliminate fossil fuel to generate electricity by 2020 and gasoline powered automobiles by 2030. Following a study which showed that 25% of per capita emission of CO2 was generated from food consumed by their population, the Nutrition Department of the Swedish National Food Administration has created new guidelines. Where the USDA considers nutrient intake and a balanced diet, Sweden is giving equal weight to carbon emission in compiling dietary recommendations.

Swedish consumers are now apprised of the apparent carbon emission associated with individual products purchased at supermarkets and from restaurants, reflecting the intentions of Walmart. According to Rosenthal, a consumer may not only select a product based on price, nutrient content and promotional text on packaging, they now have a CO2 declaration to consider in the purchase decision. The stated value quantifies the mass of carbon dioxide expressed in kg generated by each kg of product. Similarly menus now post CO2 emission values. This will enable a customer to select between a hamburger apparently rated at 1.7 kg CO2 or a chicken sandwich at 0.4 kg CO2.

As with most grand schemes, especially those promoted by government bureaucrats, the devil is in the details. The assessment of the CO2 declaration to be applied to a food product is subject to considerable variation according to method of cultivation, processing and packaging. This is just the kind of number manipulation that allows commentators such as Michael Pollan to erroneously claim that a driver of a Hummer eating a salad produces less CO2 than the driver of a Prius consuming a hamburger.  Basically driving and eating is hazardous to one’s health irrespective of the vehicle, maybe just as hazardous as following the dictates of trendy advocates of a vegan lifestyle.

It is probably legitimate for the Scandinavian Organic Certification Program to ban the use of fossil fuels for production of food products in hothouses. This will inevitably result in importation from warmer climates or nations with less restrictive regulations. Unfortunately this will involve expenditure of fuel for transport, somewhat offsetting the basic objective of reducing carbon emissions. By selectively manipulating data and ignoring obvious realities, the system can apparently warm the hearts and consciences of the do-good Nordic Nations.

The bottom line is that if a system of enforced declaration of CO2 emission for individual products is introduced in the U.S. either by governmental edict or misplaced good intentions of the supermarket chains, we had better have some scientifically based ground rules to ensure consistency and accuracy. If the emissions associated with cultivation of carrots can vary by a factor of 10 as influenced by soil type, according to Rosenthal, we will need strict directives to ensure a level playing field. Given a program which assigns a single number without qualifications, there will be a natural incentive to rig results to achieve a competitive advantage. Witness the fuel consumption claims by manufacturers of hybrid and alternative power vehicles which are continually being challenged as new models and technology emerge. Even our government is inclined to ignore facts or distort numbers relating to production of biofuels.

There are profound difficulties in selecting a specific number for carbon emissions, even with appropriate scientific techniques. Washington may develop a system analogous to the Department of Homeland Security color coding for the risk of a terrorist attack. We are all aware of how helpful this has been. Probably as informative and useful as a CO2 declaration on a food package.