( CNN ) -- Many leading brands , including Cadbury-Schweppes , Tropicana and Tesco , have begun introducing `` carbon labeling '' on products to give customers an idea of the environmental impact of the food that they are buying . How much carbon has that created ? Food with CO2 emissions labels can be confusing . CNN spoke to Tara Garnett , director of the UK-based Food Climate Research Network , an initiative committed to reducing greenhouse gas emissions from the food chain , about the pros and cons of the system . CNN : How do carbon emissions arise in food production ? Garnett : Only talking about carbon emissions is actually a bit of a misnomer . We should be looking at the full spectrum of greenhouse gases produced during food production . Once food has left the farm gate , then we are mainly dealing with carbon dioxide from transport and packaging . But while on the farm it 's nitrogen oxide and methane . They are present in smaller quantities but are much more potent in terms of the effect they have . CNN : What proportion of our carbon emissions come from food ? Garnett : Estimates vary . For the UK it 's around 19 percent , but one EU report puts European emissions at 31 percent . The thing to understand is this is a relative statistic , so if you 're talking about a society where people do n't have many cars and TVs , then the proportion will be quite high . It may actually be lower in countries with a high material standard of living . Also , the estimates differ depending upon the boundaries they use , what 's included and what 's not included in the calculations . CNN : Do you think food-miles are a useful measure of the environmental impact of food ? Garnett : They have been useful in raising awareness of where food comes from and how it is transported , but in real environmental terms it 's more useful to look at total greenhouse emissions . When we do that then there are often quite counterintuitive results . For example , it might be more environmentally friendly to truck tomatoes from Italy to northern Europe rather than grow them in heated greenhouses closer by . Also , different modes of transport have different footprints ; sea freight is better than road , for example . CNN : What does carbon labeling hope to achieve ? Garnett : Well , it 's predicated on the assumption that it will persuade consumers to make the right choice to cut their emissions , and I 'm not sure it will . That would depend on having the time to construct a very consistent , clear message , and I 'm not sure we do . Carbon labeling could be very good for manufacturers , to help them understand the wastage and unnecessary expense in their business , but if it 's left to consumer choice I 'm not sure it will achieve the wholesale shift towards more sustainable living that we need . Just buying low carbon chips wo n't change anything ; we need to reduce the overall percentage of the high impact foods -- meat and dairy -- in our diet . CNN : Is there a global standard of labeling ? Garnett : There are a plethora of different labels in Europe and the U.S. , and at present there is n't a global standard . It would certainly be a good idea , and at the European level it looks quite likely . But I 'm not sure about the U.S. My impression is that they are quite behind on food awareness . CNN : Do you think labeling can reduce carbon emissions in the food production system ? Garnett : That depends on significant interest from consumers in their carbon emissions , which I 'm not sure exists . But even if it does , shaving 10 or 20 percent off certain products does n't create a different mind-set . Low carbon snacks wo n't change the world . We need to be asking : do we need all this stuff ? The science says we need to make 80 percent cuts in emission by 2050 , and we just do n't have time to be trimming the edges . CNN : Do you think labeling could damage developing world economies that are based around exports ? Garnett : Possibly . When the Soil Association ( a British organic certification body ) had a consultation on whether they would certify air freighted products , there was an outcry from the UK Department for International Development as well as producers overseas . But they might find if we looked at total carbon emissions rather than food miles , they might do better , with hours of free sunshine and long growing seasons reducing the need for heating and other inputs . CNN : Do you think labeling will change consumer behavior ? Garnett : We need a far stronger steer from government on what a low-impact lifestyle looks like . Tinkering around with elements of consumer behavior wo n't deliver the changes we need . The government needs to be involved . We need to work on choice editing , and make sure products are sending the right signals to consumers about the kind of diet they need to adopt , but they are very scared of doing this . There are certain synergies with health that could be exploited -- less meat and dairy is better for us as well as the environment . We need to be looking at the portions of meat and dairy in ready meals , and getting people used to a different way of eating . I think a lot can be achieved in quite subtle ways , as well as with more gung-ho regulation . Ultimately , this is a systemic problem . Of course public awareness and information is important , but to get the change we need we will have to take drastic action . We just have n't got time to woo people for years . We need to act right now .
Food and climate expert Tara Garnett talks to CNN about carbon labeling . Garnett : Low carbon foods not answer ; we need to reduce `` high impact foods '' in diet . Garnett : Carbon labeling not always clear for consumers but good for manufacturers .