The Cost of Food
Everything we eat has environmental costs. We trade human health and nutrition for some necessary amount of environmental disturbance, though we should always strive to reduce our dietary impact. Seafood causes less environmental damage than other animal proteins (and many plant-based foods), and should be considered in any low-impact diet. Farmed shellfish, like oysters and mussels, are probably the very best food you can eat for the planet, regardless of plant or animal.
Humans, by way of greenhouse gas (GHG) emissions, are causing several global environmental disruptions. Carbon dioxide (the most emitted GHG) in the atmosphere traps heat, causing global temperatures to rise. The increased heat causes higher sea levels, more droughts and heat waves, abnormal rainfall patterns, and more intense storms—all of which threaten human well-being around the globe.
Generally, proteins are the most carbon-intensive nutrient our bodies require. Below is a graphic from the World Resources Institute comparing the amount of GHG emitted per gram of protein.
Beef, lamb, and goat (grass-eaters) are the most brutal to the planet because they are ruminant animals—they rely on specialized bacteria in their gut to break down food. These bacteria release a large amount of methane, a potent GHG that strongly contributes to global warming.
The emissions impacts of other complete, animal proteins are mostly related to how much food is needed to raise and care for the animal. For example, chickens are more efficient than turkeys at turning food into flesh and thus have a marginally lower impact. Animal feed needs to be grown, harvested, processed, and shipped to farms—all contributing to emissions. Wild-caught fish do their own feeding and growing, thus they have the lowest emissions among animal proteins. Commercial fishing emissions mostly come from boat fuel burned to go fish, akin to tractors harvesting a crop.
Emissions from plant-based proteins are directly related to their protein density. Food needs to be harvested, packaged, and shipped—all incurring GHG costs—meaning denser foods provide more protein for the weight. There is more protein in a pound of fish than in a pound of nuts, thus GHG emissions per gram of fish protein is lower.
A prominent 2014 study in Climatic Change (open access) took a more holistic approach to dietary GHG emissions by examining the daily emissions of different kinds of diets. Researchers categorized people into groups: high, medium, and low meat-eaters; fish-eaters; vegetarians; and vegans. The results are mostly what would be expected: eating more meat produces more emissions. However, fish are a delicious exception! Fish-eaters (who consumed no other meat) have nearly the same emissions profile of strict vegetarians, differing by about 1%. Vegans are the least impactful eaters.
Most people in the U.S. and other developed countries are high meat-eaters, consuming over 1.5lbs per week. One high meat-eater replacing that meat with fish would save the emissions equivalent of about 6,000 miles driven over the course of a year.
Space & Water
GHG emissions are the most important consideration in food sustainability, but eating wild-caught fish has two more key advantages over land-based food: space and water. Agriculture uses 38% of the world’s land and accounts for over 90% of freshwater use. With world population projected to reach over 9 billion by 2050, the increased demand for food will further stretch our land and freshwater resources.
Agriculture is responsible for the clearing of millions of hectares of forests & grasslands; the diversion, contamination, and scarcity of freshwater rivers and lakes; and the extinction of countless species around the world. At the same time, world hunger is at an all-time low and more people than ever have access to a healthy life provided by food. Humans have traded space, water, and biodiversity for health and welfare, however, we should still aim to conserve as much as we can.
The amount of space we protect from agriculture is largely dependent on what kind of food we eat—not every kind of food has the same environmental footprint. For example, just 4 agricultural commodities, beef, soy, palm oil, and wood products, are responsible for nearly all cleared rainforest. Land-based meat, specifically meat from grass-eaters, plays a hugely disproportionate role in deforestation since most of the world’s soy is produced as feed for livestock. Demand for beef and other red meat is, by far, the largest driver of deforestation around the world.
With food production increasing, it may be strange to think that the availability of freshwater is at an all-time low. Water is more essential than anything else, yet people have less of it than ever. Some is diverted to dams for electricity, but most of the world’s water supply is used for growing crops and livestock. Many people in the world do not have easy access to potable drinking water. Much of this is caused by water pollution—in which agriculture plays a large role. Pesticide and fertilizer runoff from agriculture is one of the leading causes of water quality degradation around the world.
In addition to being one of the most carbon-efficient foods on the planet, wild-caught fish require no land, no freshwater, and has a much lower impact on wildlife—no marine fish has ever gone extinct due to fishing. Farmed seafood has some similar impacts as land-based food, but is highly dependent on the kind of seafood being cultivated. Farmed sea vegetables (e.g. kelp) and farmed bivalves, like oysters, mussels, and clams are extremely good for the environment. They are typically grown right offshore (requiring little to no boat fuel), require no freshwater, can be grown vertically using very little ocean space, and actually take carbon out of the environment as they grow. Oysters could possibly be the best commercially available food to eat as they are typically eaten raw – no cooking energy used at all!
The above chart from World Resources Institute does a great job summarizing the environmental costs of our food (though wild-caught fish and mariculture species are excluded from the figure). Essentially, eating more fish in place of other animal-based foods is better for the planet. But not all seafood is equal—there is much that determines how sustainable a particular kind of seafood from a particular location is. In the next section we dive into every aspect of fisheries and sustainability.
This post is part of Sustainable Seafood 101.
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