Nitrogen emissions such as ammonia and nitrogen oxide impact the environment in a number of negative ways. These include damage to forests and buildings, as well as respiratory and other health problems in humans. 

In this study, researchers used an assessment model developed by the Food and Agriculture Organization of the United Nations, designed specifically to look at how animal agriculture affects the environment, and it involved identifying how much agricultural activity is taking place within squared cells of land of around 10km x 10km in size. The level of greenhouse gas emissions from those areas was then analyzed against the presence of agriculture. This helped researchers to understand how different activities such as manure management and soil fertilisation influence emissions, including nitrogen. 

The researchers found that increasing demand for animal-based food has led to a steady increase in exports around the world. For example, over the past three decades, the United States has been exporting cow meat at an increasing volume of 7% per year. Importers do not count the nitrogen emissions caused by international trade, so domestic environmental policies are not targeted towards solving this problem. The study identified global and regional hotspots where emissions are most concentrated, and found them to be mostly based in Asia and North America. 

Overall, the study concluded that our food system requires urgent change to tackle pollution caused by nitrogen emissions. The researchers estimated that animal agriculture is responsible for around a third of all emissions caused by humans. Of this, 68% is due to feed production, especially when crops are then transported and used to feed animals living on other parts of the globe. Around 66% of nitrogen emissions occur in Asia, which has the fastest rate of human population growth. 

What do all these nitrogen emissions mean for the environment? They make a significant impact on climate change and biodiversity loss. When too much nitrogen enters the environment, it can pollute streams and rivers as well as the air. Nitrogen in the water causes algae to grow faster than normal, which reduces the amount of oxygen available to fishes and other wildlife. Even low levels of nitrogen in our drinking water can cause health problems. 

Recommendations from the study include encouraging farmers to transport and recycle manure, though this may be too expensive in practice. The researchers also suggested designing agricultural systems to be less concentrated, with fewer animals packed together. Since this concentration is a result of the increasing demand, it’s difficult to see how this could happen without a rise in prices. It might be useful to advocate for this scenario, as more expensive products would likely reduce the numbers of animals being used for food. 

The study recognized that these measures may not be enough. It goes as far as to say that, in some parts of the world, a reduction in consumption of animal-based food is probably necessary. However, the researchers say that this should not come at the expense of food security. Animal advocates might highlight how a plant-based food system can improve, rather than threaten, food security. Another angle might be to address how inefficient the current food system is, in terms of the difference in resources needed to produce animal and plant-based foods. 

The final recommendation from the authors is to create a global initiative to combat nitrogen pollution through better management of animal-based food production. This initiative should represent consumers, academics, and people from the agricultural sector. If such a group is created following this study, perhaps there will be space to discuss alternatives to animal agriculture, or strategies which could lead to reduced consumption overall. This, of course, goes hand-in-hand with a need for widespread availability of plant-based food and an increased societal awareness of animal suffering.