Environmental Cost of Protein


When you buy protein, whether plant or animal based, do you think about the environmental costs that go into the production of that protein? Even plant based protein has some environmental cost. The greenhouse gas emissions from mass processing of protein continue to rise with the increased global demand for animal based protein. Livestock production requires feed and to grow that feed requires the use of fertilizers, particularly nitrogen fertilizers. The use of the nitrogen fertilizers contributes to an increase in nitrous oxide, one of the main greenhouse gases contributing to global warming. Production of feed also releases carbon dioxide, another greenhouse gases.  Even the manure produced contributes nitrous oxide to the environment along with the animals themselves emitting methane.
            A 2011 study by the Environmental Working Group assessed the impacts of 20 popular types of meat, fish, dairy and vegetable proteins. The study looked at the “cradle-to-grave” carbon footprint of each protein type based on the greenhouse gas emissions generated before and after the protein left the farm. They calculated emissions that included the fertilizer used to grow the animal feed, animal processing, transportation, as well as the emissions from cooking. It was found in the study that lamb, beef, cheese, pork and farmed salmon generated the most greenhouse gases.
While it may be impossible to completely cut animal based protein from our diets we can all try and reduce our intake. That will in turn reduce demand of animal based protein and thus lower greenhouse gas emissions.


Figure 1. Full Lifecycle Greenhouse Gas Emissions from Common Proteins and Vegetables
The chart below shows the lifecycle total of greenhouse gas emissions for common protein foods and vegetables, expressed as kilograms (kg) of carbon dioxide equivalents (CO2e) per kg of consumed product.Greenhouse Gas Emissions from Common Proteins and Vegetables


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