Recently a study out of Dalhousie University estimates the environmental cost of future livestock production. Using numbers from other studies that predict future levels of livestock production researchers Nathan Pelletier and Peter Tyedmers calculate the environmental impact from now until 2050. Their study was published in the Proceedings of the National Academy of Sciences this month and calls for policy makers to take action.
The study states that in 2000 livestock contributed 14% of greenhouse gases and by 2050 will rise to 39% in the predicted production level scenario (Pelletier and Tyedmers 2010). They also looked at two other areas: biomass appropriation, and reactive nitrogen mobilization. They predicted an increase in both of these measures as well. These areas were estimated for three different scenarios: a substitution scenario where poultry was substituted for beef production, a scenario with the predicted levels of production, and a scenario with no livestock production where humans would get all necessary protein from soy products. The results of each were then compared to proposed sustainability thresholds from a former study done in 2009 called Updating the world on the latest climate science. The earlier study concludes that if these thresholds are surpassed then by 2050 the mean surface temperature of earth will increase by 2˚C, which could cause hazardous consequences (Pelletier and Tyedmers 2010).
Starting from left to right are the levels of greenhouse gas emissions, biomass appropriation, and reactive nitrogen mobilization for the predicted production scenario compared with the proposed sustainable levels for each (Pelletier and Tyedmers 2010). The arrows along the outside represent the sustainably values and the arrows on the inside represent the predicted contributions due to livestock in 2050. As you can see the amount of reactive nitrogen mobilization is far past what is thought to be sustainable. Keep in mind that this is only measuring the amounts from livestock production, and with the addition of other contributors would clearly surpass each threshold.
Pelletier and Tyedmers were conservative in their estimates due to the large amount of uncertainty that comes with predicted future values of anything. They also assumed that in the next 40 years the livestock industry would find better production methods to lower their contribution to greenhouse gas emissions. It is very difficult to predict how much improvement will occur which leads to more uncertainty in their numbers. The one thing that is certain is that if livestock production increases so will the emissions of greenhouse gases regardless of how much it is in the best interest of reducing global warming to find greener alternatives.
Pelletier and Tyedmers conclude at the end of the paper that policy makers must focus on ways of deterring consumers away from livestock with greater impact such as hogs or beef, to species with lower impacts such as poultry or fish or soy. They also realize that the scenarios they used are unrealistic and are rather used to show a range in which is realistic goal is achievable. In an interview done after the study was published Pelletier talks about how food is one type of consumption that we have a lot of choice as to what and how much we consume. This is an area where consumers can easily recognize the environmental implications of their nutritional choices (Pelletier 2010). Clearly livestock production will not be completely halted for all soy protein products and clearly not all beef will be substituted for poultry. Policy makers must find creative ways to influence consumers to find a better balance of these three protein products and consumers must make smarter decisions regarding food consumption.
Pelletier, N., & Tyedmers, P. Forecasting potential global enviromental costs of livestock production 2000- 2050. Proceedings of the National Academy of Sciences. 106(41).
www.pnas.org/cgi/doi/10.1073/pnas.1004659107
By: Joel Schillings
Dalhousie news release
http://dalnews.dal.ca/2010/10/05/beef.html
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