Nitrogen pollution is poisoning the planet – and barely anyone is talking about it
Human activity is releasing far more reactive nitrogen than the Earth can safely absorb, damaging climate, biodiversity, human health, soils and oceans.
Nitrogen, as any diver can tell you, can be deadly – especially when it forms bubbles in the bloodstream and causes painful decompression sickness. Yet we breathe it in and out all our lives without ill effect.
However, this apparently innocuous substance, in its reactive forms, is now responsible for a global environmental disaster that is driving extinction, ruining our health, overheating the planet and killing the oceans.
The most terrifying feature of nitrogen pollution is that so few people realise it is happening – or that we ourselves are the main cause of it, through our eating, shopping and travel habits.
“Nitrogen pollution is causing an environmental catastrophe with devastating consequences for Planet Earth – yet the scale of the problem remains largely unknown outside of scientific circles,” warns the United Nations Environment Program (UNEP).
Furthermore, humans are releasing three times more nitrogen into the Earth system than it naturally circulates, inflicting a form of planetary poisoning outside the ken of most societies, industries and governments. According to the Potsdam and Stockholm Institutes, humans are releasing around 165 million tonnes of nitrogen a year into a biosphere which has a safe limit of 62 million tonnes. Of the ‘safe planetary boundaries’, it is the one we have transgressed the worst.
When people think about major pollutants that are changing the habitability of the Earth, the one that springs most readily to mind is carbon dioxide (CO2). Each year we add an additional 40 billion tonnes of that gas to heat the planet.
Though our emissions of nitrous oxide (N2O), mainly from vehicles, factories, farms and coal-fired power stations, are far smaller, N2O is 300 times more potent as a planet heater and lingers in the atmosphere for two centuries or more. But its other effects are far worse.
Nitrogen pollution is now the third worst driver of extinction of plants and animals. It degrades soils, waterways and groundwater and causes dead zones to form in the oceans. It makes our diet poorer and poisons the air of big cities, affecting 77 per cent of the human population and causing widespread lung disease for millions.
As with coal, agriculture, transport, nuclear energy and now AI, the story begins with a wonderful discovery of a new technology that humans have since used to such excess it has become a planet killer.
It starts in 1909 with two German chemists, Fritz Haber and Carl Bosch, who demonstrated a process for extracting nitrogen from air and turning it into ammonia (NH4) which could then be used to make fertiliser for farmers to grow more crops and pastures. They both won Nobel Prizes for what seemed at the time like a very humane discovery.
The global use of industrial nitrogen fertilisers took off with the Green Revolution in the 1960s–70s. One of the immediate effects of the jump in food supplies was a sharp drop in infant mortality – and the current human population boom which has now reached 8.3 billion, heading for 9.7 billion by 2050. The boom in population led in turn to a boom in food demand, which led to a further boom in demand for fertilisers. This boom cycle is still under way, with a projected 50 per cent increase in food and fertiliser demand by mid-century.
The problem with nitrogen fertilisation is that it is very inefficient. More than half of what the farmer spreads on his fields is lost into the environment, where it causes all sorts of problems including toxic algal blooms in waterways and dead zones in the ocean, acid soils, biodiversity loss, depletion of micronutrients and poisoning of city air and groundwater. “Globally, overuse of nitrogen (N) fertilisers in croplands is causing severe environmental pollution,” states a scientific review.
The same applies to nitrogen emitted by fossil-fuel burning in vehicles, power stations, homes and factories and also industrial wastewater. This is almost all lost into the environment, where it causes havoc.
Children are especially at risk from nitrogen pollution, warns UNICEF. The damage begins with air inhaled by the mother before a baby is born, causing oxidative stress to the foetus and harm to its development of heart, lungs, immunity, hormones, nerves and brain. This damage continues in infancy, because young children inhale proportionately more air than do adults, making them more susceptible to poisons affecting development. It can especially affect lung development of both girls and boys in adolescence.
In a disturbing side-effect, the overuse of N, P and K fertilisers in agriculture has caused “an alarming decline in food quality” and a decrease in a wide variety of essential minerals and nutritive compounds in fruits, vegetables and food crops. It isn’t just Big Food corporates adding more rubbish to the modern diet. The very process of growing crops and pastures on soil with heavy applications of fertiliser means that the accelerated plants then strip other essential nutrients from the soil. You get heavier, less nourishing crops. As time goes by, the soils grow more depleted – and deficiency diseases begin to show up among human consumers. One of the more bizarre consequences is a tripling in rates of scurvy, often among people who subsist on fast food and avoid fresh fruits and vegetables.
Thanks to nitrogenous fertilisers, modern agriculture is no longer husbandry – it has become a form of mining. And all mines eventually run out.
The addition of excess nitrogen to rivers and the ocean has similarly grave consequences – vast blooms of algae, some of them extremely toxic. When these die off, they are decomposed by blooms of bacteria which also strip the oxygen from the water, causing fish, molluscs and other aquatic animals to die. These form the ‘dead zones’ seen at the mouth of the Mississippi river, in Chesapeake Bay, the Baltic Sea, the Black Sea, the Yangtze delta and along most of the world’s industrial coastlines. The universal spread of ocean dead zones is thought by scientists to have played a significant role in the five previous mass extinctions of life on Earth.
While there are technical ways in which nitrogen emissions can be reduced in agriculture, also by switching to clean energy, electric vehicles and imposing stricter rules on industrial discharges, the fact remains that they are a primary outcome of human overpopulation of the planet – and the ultimate solution is a voluntary reduction in both population and its nitrogen emissions to a level the Earth can support.
The views expressed in this article may or may not reflect those of Pearls and Irritations.
