Ray Hilborn, Jeannette Banobi, Stephen J Hall, Teresa Pucylowski, Timothy E Walsworth. The environmental cost of animal source foods. Frontiers in Ecology and the Environment https://doi.org/10.1002/fee.1822
Consumers and policy makers aiming to make informed choices about what animal protein food sources to support have a new resource available this month, thanks to a review led by University of Washington researchers.
Our food production systems are complex and the environmental impacts of any one food source are multi-faceted. How can we tell whether livestock, wild-caught fish, or farmed seafood are least environmentally costly to produce?
Researchers typically attempt to quantify the combined impacts of a single animal food production process by conducting what are called “life-cycle assessments.” These disparate “cradle-to-grave” assessments are informative in their own right, but the team, led by Dr. Ray Hilborn, hoped to identify broader patterns by systematically reviewing the results of a large group of these life-cycle assessments together.
From over 300 published life-cycle assessments of livestock, farmed seafood, and wild-caught fish, Hilborn and his team narrowed their scope to 148 assessments that studied conventional mass-production methods. These included conventional production methods for shrimp, catfish, tilapia, beef, chicken, and pork, among other animal protein sources. Small-scale, organic, and specialized production methods were excluded.
For this study, the researchers considered four metrics of environmental effects: energy use, greenhouse-gas emissions, potential to release excess nutrients, and potential to release substances that contribute to acid rain. These effects were standardized across all assessments by calculating the impact the production of a serving of forty grams of protein would yield. Forty grams is approximately the US Department of Agriculture’s recommended minimum daily amount of protein for a healthy adult.
Broadly, the analysis showed that farmed mollusks (like oysters, scallops, mussels) have the lowest environmental impact across all four categories. Those hoping for generalizations will have to be satisfied there though; there is much variability and nuance within the proteins that constitute livestock, farmed seafood, and wild-caught fish across the four metrics. For example, livestock production generally uses less energy than farmed seafood, but typically generates more greenhouse gas emissions. While we can’t broadly paint one protein source as more environmentally sound than the other, we can find guidance to make more informed choices as consumers by understanding the impact of our food options. Here are some of the findings:
- In general, livestock (beef, chicken, pork) production uses less energy than farmed or wild-caught seafood, with the exception of mollusks and other small fish. Farmed fish that require electricity for water circulation use the most energy.
- Beef and farmed catfish contributed to the greatest release of greenhouse gas emissions—more than 20 times higher than farmed mollusks and small fish like sardines and anchovies.
- Most food sources contribute to the release of excess nutrients, which can lead to ecologically disruptive phenomena like algal blooms. These explosive growths of algae can release harmful toxins that endanger humans and wildlife alike; algal blooms can also consume all the oxygen in an area of water, creating ‘dead zones’ where aquatic species can’t survive. Wild-caught fisheries, however, do not require the addition of external fertilizer, so they scored lower than livestock and farmed seafood. The clear winner in this category is farmed mollusks, which actually absorb excess nutrients from the environment.
- Livestock farming has the greatest impact on acid rain, from the emission of methane from manure. Wild-caught fishing practices also contribute to acid rain, but here the source of emissions is the fuel used to power the boats.
When considering the environmental impact of our food choices, this new resource helps provide a road map for informed decision-making.