New research shows that the synthetic nitrogen fertiliser supply chain was responsible for estimated emissions of 1,250 million tonnes of CO₂ in 2018.
This is approximately 21.5% of the annual direct emissions from agriculture (5,800 million tonnes).
Three scientists working with Greenpeace, the Institute for Agriculture and Trade Policy (IATP), and GRAIN conducted the research.
It provides the first estimate of the global climate impacts of synthetic nitrogen fertilisers to cover the entire production chain, from manufacturing to soil application.
They found that the production and use of synthetic nitrogen fertiliser accounts for 2.4% of global greenhouse gas (GHG) emissions. This makes it one of the top climate polluting industrial chemicals.
“The majority of emissions from synthetic nitrogen fertilisers occur after they are applied to the soil and enter the atmosphere as nitrous oxide (N2O) – a persistent greenhouse gas with 265 times more global warming potential than CO₂.”
“But, what is less discussed is that almost 40% of the GHG emissions of synthetic nitrogen fertilisers occur in production and transport, largely in the form of CO2 caused by the burning of fossil fuels during manufacture.”
“Added up, a full accounting of emissions from synthetic nitrogen fertiliser shows how it is a major source of climate pollution that needs to be rapidly and drastically reduced,” states the research.
Increase by 800% since the 1960s
According to new research, synthetic nitrogen fertilisers are a major driver of the climate crisis.
They are responsible for 1 out every 40 tonnes of GHGs currently pumped into the atmosphere.
According to the Intergovernmental Panel on Climate Change (IPCC), synthetic nitrogen fertilisers have increased by 800% since the 1960s.
The paper says the new research confirms that climate pollution from synthetic nitrogen fertilisers production and use is on course to worsen if we do not take action to reverse these trends.
According to the United Nation’s Food and Agriculture Organisation, the worldwide use of synthetic nitrogen fertilisers is set to increase by over 50% by 2050.
Furthermore, the research found that emissions from synthetic nitrogen fertilisers are highly concentrated in certain geographic areas.
China, India, North America and Europe are the main emitters.
But, on a per capita basis, the highest emitters are the big agricultural export countries of:
- North America (the US and Canada);
- South America (Argentina, Brazil, Paraguay, Uruguay);
- Australia/New Zealand;
- Europe (Denmark, France, Ireland, Ukraine).
“Worldwide, emissions keep growing every year, including in Africa, where fertiliser use is now growing rapidly.”
‘Green revolution’ model
They contend that the ‘green revolution’ model of agriculture, introduced in the 1960s, has contributed heavily to the increased use of chemical fertilisers.
This model is based on developing and adopting varieties of certain staple crops (mainly wheat, rice and maize) that are:
- Short and stocky (called semi-dwarf);
- Capable of producing high yields when heavily dosed with chemical fertilisers and sprayed with pesticides.
“The green revolution varieties quickly replaced local varieties and generated a huge boom in the global use of chemical fertilisers”
“They also kicked in a vicious cycle, in which more and more chemical fertilisers had to be applied to sustain yields.”
“Today, only around 20-30% of the synthetic nitrogen fertilisers applied to fields are converted to foods. The rest runs off into water bodies and entering the environment as pollution.”
The research paper says that the fertiliser lobby has spent several decades maintaining that the excessive use of synthetic nitrogen fertiliser can be resolved through more precise application – what they call ‘precision agriculture’ or ‘climate-smart agriculture’.
“Yet the new research on synthetic nitrogen fertiliser emissions finds no evidence that programmes to increase efficiency have had any significant impact.”
“In most world regions, there has been no significant increase in crop production per unit of synthetic nitrogen fertiliser applied.”
Ireland’s Climate Action Plan: Reduce chemical nitrogen fertiliser use to 325,000t/annum