When “food miles” are not all about distance.
I have just finished taking an online course about health and global environmental change*, and during the course section on food and sustainability I came across an example about the concept of “food miles” and sustainability that I thought would be interesting and fun to share.
Let’s say you live in Chicago, and you’re looking to buy a bottle of wine for tonight’s dinner. You have a choice between a wine from California, or one from France. Being the environmentally conscious person that you are, you would like to buy the bottle of wine that has the least impact in terms of greenhouse gas emissions. Which should you choose?
If you are unsure of how to make the right choice, don’t worry, the legwork has already been done for you. In a study published in the Journal of Wine Research in 2009, T. Colman and P. Päster developed a model to quantify greenhouse gas emissions associated with the production and distribution of a bottle of wine.
According to their data, there is a two-fold difference in carbon intensity (carbon dioxide, or CO2, emissions) between a bottle of wine from California and one from France (if you live in Chicago). However, while there are some small variations at the production level (CO2 emissions related to land use, cultivation, etc.), distribution is what contributes the most to the difference in total CO2 emissions. The reason for this is double: 1) shipping actually represents the largest part of total CO2 emitted during production and distribution of the bottle of wine, and 2) the modes of transport for the Chicago-France and Chicago-California shipments are different.
If I now tell you that sea freight is the least carbon-intensive mode of transport, that the French bottle of wine was mostly transported by ship, and that the Californian wine was solely shipped by truck across the US to Chicago, you can probably guess which wine you should choose to minimize the climate impact of your evening’s drink.
T. Colman and P. Päster included in their paper a map of the US on which they had drawn a line to represent the approximate “break-even” point in terms of greenhouse gas emissions between a French wine and a Californian wine (line that I reproduced approximately on the map below). So if you live East of the following state borders: Minnesota-Wisconsin, Nebraska-Iowa and New Mexico-Texas, you should choose a French wine to effectively buy the bottle associated with the least CO2 emissions (as of 2009 at least, when the study was published).
Now, if you prefer Australian wine, don’t worry. A bottle shipped from Australia through the Panama canal, up to the New Jersey coast, and loaded onto a truck to reach Chicago, will be associated with a lower amount of greenhouse gas emissions than the same bottle shipped from California to Chicago by truck.
The take-home message from this particular example about wine bottles and distribution is that mode of shipment is important, not just miles. So next time you think about “food miles”, try to think about how the product was shipped, on top of where it came from.
Red, White, and “Green”: The Cost of Greenhouse Gas Emissions in the Global Wine Trade. Tyler Colman & Pablo Päster. Journal of Wine Research. 18 Jun 2009. doi: 10.1080/09571260902978493.
* The course is a MOOC offered by edX (HarvardX more precisely). Unfortunately, the course will not be available online for auditing after it ends (at least for some time), but if it becomes available, I would recommend it to anyone who is interested in issues of climate change, human contribution to global warming, mitigation, adaption, and effects on global human health.
Tyler Colman & Pablo Päster (2009). Red, White, and “Green”: The Cost of Greenhouse Gas Emissions in the Global Wine Trade Journal of Wine Research DOI: 10.1080/09571260902978493