Emissions of greenhouse gas nitrous oxide soaring due to fertiliser

Emissions of greenhouse gas nitrous oxide that is 300 times more potent than CO2 have increased by a THIRD over the past 40 years due to growing use of fertilisers in food production

  • Nitrous oxide levels set to carry global temperatures beyond Paris Agreement  
  • Heavily driven by emissions caused by fertiliser and manure in agriculture  
  • Researchers created the most comprehensive list of nitrous oxide sources and sinks yet 

Widespread use of nitrogen-based fertiliser is jeopardising ambitious climate targets and putting the world at risk of overshooting the Paris Agreement.  

Common synthetic fertilisers, used by farmers to increase crop growth, produce huge amounts of nitrous oxide (N2O), a greenhouse gas. 

It is less prevalent than carbon dioxide, but is 300 times more potent as a contributor to global warming. 

The dangerous gas depletes the ozone layer, which protects us from the harmful ultraviolet rays of the sun, and remains in the atmosphere for a century.

A landmark study has found human-induced emissions of the chemical have surged since the 1980s, increasing by 30 per cent over the past four decades.

Annually, humans now create 7.3 trillion grams (Tg) of nitrogen a year and more than half (3.8 trillion grams [3.8Tg]) comes directly from agriculture.  

This figure is increasing every year at a rate of around 1.4 per cent, according to the data. 

The researchers warn that if N2O continues being spewed out at its current rate, global temperatures will soar to 3°C above pre-industrial levels by 2100.  

The Paris Agreement is a landmark set of environmental targets signed by almost all nations in 2015, which aims to limit warming by the end of the century to less than 2°C, but hopes to hit its more ambitious target of 1.5°C. 

Common synthetic fertilisers, used by farmers to increase the growth of crops, produce huge amounts of nitrous oxide (N2O), a potent greenhouse gas

An international team of researchers found the agricultural release of nitrous oxide totals 3.8 trillion grams (3.8Tg) of nitrogen a year, more than half of all man made N2O emissions. Pictured, all sources and sinks of N20, according to the latest research 

An international team of researchers from 48 institutions, including the University of East Anglia in England, and led by Professor Hanqin Tian at Auburn University, have published a study mapping the world’s nitrogen cycle.  

Researchers uncovered the alarming increase by comparing the current amount of atmospheric N2O (331 parts per billion in 2018) to pre-industrial levels (270 ppb in 1750).   

Co-author Glen Peters, research director at the Center for International Climate Research, says fertiliser accounts for two thirds of the startling 3.8Tg figure. 

‘Excess fertiliser makes great food for soil bacteria and enhances the microbial processes that lead to nitrous oxide emissions,’ he says.

‘The remaining one-third comes from livestock manure, with the emissions being the result of microbial processes that break down nitrogen-containing compounds in the soil and oceans. 

‘These are the same microbial processes that lead to natural nitrous oxide emissions.’

The researchers broke down where nitrous oxide comes from (the source) and where it is absorbed (the sink). 

They found that while nitrous oxide is a major contributor to the agricultural source, it also adds to the cumulative total indirectly. 

For example, nitrogen trapped in fertiliser and manure can be transported to other regions away from their original location. 

‘Excess nitrogen may be transported to other places through water runoff and atmospheric dispersion, which leads to further nitrous oxide emissions,’ explains Dr Peters.

The study data shows that only two regions — Europe and Russia — have decreased their manmade N2O emissions since 1980 (pictured). In Europe, this is attributed to several factors, including the removal of N2O from flue gases, an emissions trading scheme and more efficient use of fertiliser


The Paris Agreement, which was first signed in 2015, is an international agreement to control and limit climate change.

It hopes to hold the increase in the global average temperature to below 2°C (3.6ºF) ‘and to pursue efforts to limit the temperature increase to 1.5°C (2.7°F)’.

It seems the more ambitious goal of restricting global warming to 1.5°C (2.7°F) may be more important than ever, according to previous research which claims 25 per cent of the world could see a significant increase in drier conditions.

In June 2017, President Trump announced his intention for the US, the second largest producer of greenhouse gases in the world, to withdraw from the agreement.  

The Paris Agreement on Climate Change has four main goals with regards to reducing emissions:

1)  A long-term goal of keeping the increase in global average temperature to well below 2°C above pre-industrial levels

2) To aim to limit the increase to 1.5°C, since this would significantly reduce risks and the impacts of climate change

3) Goverments agreed on the need for global emissions to peak as soon as possible, recognising that this will take longer for developing countries

4) To undertake rapid reductions thereafter in accordance with the best available science

Source: European Commission 

These indirect emissions are responsible for around 15 per cent of the global N2O output, and are also growing at a rate of around one per cent a year.  

‘The dominant driver of the increase in atmospheric nitrous oxide comes from agriculture, and the growing demand for food and feed for animals will further increase global nitrous oxide emissions,’ says Professor Tian. 

‘There is a conflict between the way we are feeding people and stabilising the climate.’

The study data shows that only two regions — Europe and Russia — have decreased their man-made N2O emissions since 1980. 

In Europe, this is attributed to several factors, including the removal of N2O from flue gases, an emissions trading scheme and more efficient use of fertiliser. 

East Asia is the region that has experienced the most dramatic increase in the last four decades, primarily driven by synthetic fertilisers. 

Fertiliser is also thought to be behind surging emissions from India and the US, whereas Africa and South America, other major polluters, are mainly due to the use of livestock manure as fertiliser.

Revealed: MailOnline dissects the impact greenhouse gases have on the planet – and what is being done to stop air pollution


Carbon dioxide

Carbon dioxide (CO2) is one of the biggest contributors to global warming. After the gas is released into the atmosphere it stays there, making it difficult for heat to escape – and warming up the planet in the process. 

It is primarily released from burning fossil fuels such as coal, oil and gas, as well as cement production. 

The average monthly concentration of CO2 in the Earth’s atmosphere, as of April 2019, is 413 parts per million (ppm). Before the Industrial Revolution, the concentration was just 280 ppm. 

CO2 concentration has fluctuated over the last 800,000 years between 180 to 280ppm, but has been vastly accelerated by pollution caused by humans. 

Nitrogen dioxide 

The gas nitrogen dioxide (NO2) comes from burning fossil fuels, car exhaust emissions and the use of nitrogen-based fertilisers used in agriculture.

Although there is far less NO2 in the atmosphere than CO2, it is between 200 and 300 times more effective at trapping heat.

Sulfur dioxide 

Sulfur dioxide (SO2) also primarily comes from fossil fuel burning, but can also be released from car exhausts.

SO2 can react with water, oxygen and other chemicals in the atmosphere to cause acid rain. 

Carbon monoxide 

Carbon monoxide (CO) is an indirect greenhouse gas as it reacts with hydroxyl radicals, removing them. Hydroxyl radicals reduce the lifetime of carbon dioxide and other greenhouse gases. 


What is particulate matter?

Particulate matter refers to tiny parts of solids or liquid materials in the air. 

Some are visible, such as dust, whereas others cannot be seen by the naked eye. 

Materials such as metals, microplastics, soil and chemicals can be in particulate matter.

Particulate matter (or PM) is described in micrometres. The two main ones mentioned in reports and studies are PM10 (less than 10 micrometres) and PM2.5 (less than 2.5 micrometres).

Air pollution comes from burning fossil fuels, cars, cement making and agriculture 

Scientists measure the rate of particulates in the air by cubic metre.

Particulate matter is sent into the air by a number of processes including burning fossil fuels, driving cars and steel making.

Why are particulates dangerous?

Particulates are dangerous because those less than 10 micrometres in diameter can get deep into your lungs, or even pass into your bloodstream. Particulates are found in higher concentrations in urban areas, particularly along main roads. 

Health impact

What sort of health problems can pollution cause?

According to the World Health Organization, a third of deaths from stroke, lung cancer and heart disease can be linked to air pollution. 

Some of the effects of air pollution on the body are not understood, but pollution may increase inflammation which narrows the arteries leading to heart attacks or strokes. 

As well as this, almost one in 10 lung cancer cases in the UK are caused by air pollution. 

Particulates find their way into the lungs and get lodged there, causing inflammation and damage. As well as this, some chemicals in particulates that make their way into the body can cause cancer. 

Deaths from pollution 

Around seven million people die prematurely because of air pollution every year. Pollution can cause a number of issues including asthma attacks, strokes, various cancers and cardiovascular problems. 


Asthma triggers

Air pollution can cause problems for asthma sufferers for a number of reasons. Pollutants in traffic fumes can irritate the airways, and particulates can get into your lungs and throat and make these areas inflamed. 

Problems in pregnancy 

Women exposed to air pollution before getting pregnant are nearly 20 per cent more likely to have babies with birth defects, research suggested in January 2018.

Living within 3.1 miles (5km) of a highly-polluted area one month before conceiving makes women more likely to give birth to babies with defects such as cleft palates or lips, a study by University of Cincinnati found.

For every 0.01mg/m3 increase in fine air particles, birth defects rise by 19 per cent, the research adds. 

Previous research suggests this causes birth defects as a result of women suffering inflammation and ‘internal stress’. 

What is being done to tackle air pollution? 

Paris agreement on climate change

The Paris Agreement, which was first signed in 2015, is an international agreement to control and limit climate change. 

It hopes to hold the increase in the global average temperature to below 2°C (3.6ºF) ‘and to pursue efforts to limit the temperature increase to 1.5°C (2.7°F)’.

Carbon neutral by 2050 

The UK government has announced plans to make the country carbon neutral by 2050. 

They plan to do this by planting more trees and by installing ‘carbon capture’ technology at the source of the pollution.

Some critics are worried that this first option will be used by the government to export its carbon offsetting to other countries.

International carbon credits let nations continue emitting carbon while paying for trees to be planted elsewhere, balancing out their emissions.

No new petrol or diesel vehicles by 2040

In 2017, the UK government announced the sale of new petrol and diesel cars would be banned by 2040.  

However,  MPs on the climate change committee have urged the government to bring the ban forward to 2030, as by then they will have an equivalent range and price.

The Paris Agreement, which was first signed in 2015, is an international agreement to control and limit climate change. Pictured: air pollution over Paris in 2019.

Norway’s electric car subsidies

The speedy electrification of Norway’s automotive fleet is attributed mainly to generous state subsidies. Electric cars are almost entirely exempt from the heavy taxes imposed on petrol and diesel cars, which makes them competitively priced.

A VW Golf with a standard combustion engine costs nearly 334,000 kroner (34,500 euros, $38,600), while its electric cousin the e-Golf costs 326,000 kroner thanks to a lower tax quotient. 

Criticisms of inaction on climate change

The Committee on Climate Change (CCC) has said there is a ‘shocking’ lack of Government preparation for the risks to the country from climate change. 

The committee assessed 33 areas where the risks of climate change had to be addressed – from flood resilience of properties to impacts on farmland and supply chains – and found no real progress in any of them.

The UK is not prepared for 2°C of warming, the level at which countries have pledged to curb temperature rises, let alone a 4°C rise, which is possible if greenhouse gases are not cut globally, the committee said.

It added that cities need more green spaces to stop the urban ‘heat island’ effect, and to prevent floods by soaking up heavy rainfall. 

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