Four reasons why the world needs to limit nitrogen pollution

Nitrogen is an abundant element in the Earth’s atmosphere. It makes the sky blue, forms the foundation of proteins in our bodies and helps make soils fertile.

However, excess nitrogen in the environment in a reactive form – which comes from the use of synthetic fertilizers, the discharge of wastewater or the combustion of fossil fuels – is a hazard, polluting land, water and air. It also exacerbates climate change and depletes the ozone layer, which is finally recovering.

The United Nations Environment Program’s (UNEP’s) 2018-2019 Frontiers Report called nitrogen pollution one of the most important pollution issues facing humanity.

This week, officials from around the world will gather online to discuss how countries can better manage nitrogen. The talks, supported by UNEP, will take place on 17 January. They are designed to facilitate the implementation of two sustainable nitrogen management resolutions passed by the United Nations Environment Assembly, the world’s highest-level decision-making body on the environment.

"Nitrogen is a primary nutrient essential for the survival of all living organisms on Earth,” said Leticia Carvalho, the Principal Coordinator of the Marine and Freshwater Branch at UNEP. “But the world needs to wake up to the issues of nitrogen waste and the opportunities to take joint action for its sustainable use.”

Here are four reasons why humanity needs to limit nitrogen pollution.

1. Nitrogen pollution is disrupting life on land and underwater

When the availability of nitrogen compounds exceeds consumption by plants, excess nitrogen gets into the environment, often filtering into aquatic ecosystems. Once there, it can cause a rapid increase of toxic algae, known as algal blooms, which deplete oxygen in water and can create coastal dead zones affecting underwater life. Nitrogen pollution is the most influential global driver of human-made biodiversity decline after habitat destruction and the emission of greenhouse gases. A landmark global agreement to safeguard biodiversity, finalized in December 2022, includes targets to reduce pollution from all sources so that by 2030, pollutants are not harmful to life and ecosystems.

2. Nitrogen is a key contributor to climate change

When nitrogen in its active form, such as in fertiliser, is exposed to soil, microbial reactions take place that release nitrous oxide. This gas is 300 times more potent at warming the atmosphere than carbon dioxide. It also remains active in the atmosphere for more than 100 years. Algal blooms in lakes and waterways, often caused by fertilizer run-off, also emit greenhouse gases.

Another issue is agricultural ammonia emissions. This is a gaseous form of nitrogen, which is emitted into the atmosphere from the housing, storage and spreading of animal manure and the spreading of synthetic fertilizer. While ammonia is not a greenhouse gas, when it’s released into the air, it acts as a base for emissions of nitrous oxide, a potent greenhouse gas.

3. Nitrogen pollution is a threat to human health

Water containing elevated levels of nitrate – a form of nitrogen resulting from animal waste, plant decomposition and fertiliser run-off –  raises the risk of infants developing methemoglobinemia, commonly referred to as “blue baby syndrome”, which can be fatal. High levels of nitrate in drinking water can also increase the risk of cancer in adults.

Ammonia emissions, as well as contributing to climate change, are an important driver for fine particulate matter pollution, reducing air quality and increasing adverse effects on human health. 

4. Nitrogen waste weighs on the economy

According to UNEP’s 2018-2019 Frontiers Report, nitrogen costs the global economy between US$340 billion and US$3.4 trillion annually when taking into account its impact on human health and ecosystems. Most of the UN’s Sustainable Development Goals, humanity’s blueprint for a better future, are linked with sustainable nitrogen management. Experts say that using the element more efficiently in food production is key to reducing the surplus nitrogen released into the environment.

UNEP is working with scientists and other stakeholders, with the support of the Global Environment Facility, to lower the impact of nitrogen on the planet.

Progress is being made. Last year, at the resumed fifth session of the United Nations Environment Assembly, governments adopted a resolution on sustainable nitrogen management. While the first UNEA resolution on Sustainable Nitrogen Management adopted at UNEA4 in March 2019, set the stage for urgent work on nitrogen, this second resolution is important because it includes both an ambition to “significantly reduce nitrogen waste globally” as well as a timeline “by 2030 and beyond".

To fight the pervasive impact of pollution on society, UNEP launched #BeatPollution, a strategy for rapid, large-scale, and coordinated action against air, land, and water pollution. The strategy highlights the impact of pollution on climate change, nature and biodiversity loss, and human health. Through science-based messaging, the campaign highlights how transitioning to a pollution-free planet is vital for future generations.