Australia's Sources of N2O Emissions
Key Insights
Agriculture Sets The National Pace
Agriculture accounts for over 90% of Australia's nitrous oxide emissions and dominates the historical picture. Levels were low through the early 20th century, around 10-20 megatonnes per year, then rose rapidly during the post‑war era and especially from the late 1970s to the early 2000s. Emissions peaked near 100 megatonnes around the turn of the century before trending down to roughly 60 in recent years. Cumulatively, agriculture adds up to over 6,000 megatonnes, dwarfing other sources.
Smaller Sectors, Subtle Shifts
Energy increased gradually from below 1 megatonne in the mid‑20th century to around 4 by the 1990s, and has been broadly stable since. Industry stayed minimal for decades, then climbed after the early 1990s toward roughly 3-4 megatonnes. Other sources grew into the 1970s-80s and have eased back to under 2. Waste edged up after the early 1990s but remains around 1. Collectively, these non‑agricultural sources are far smaller than agriculture in both yearly emissions and historical contribution.
Actionable Summary And Outlook
The dominant driver-agriculture-has been on a downward trajectory since the early 2000s, moving from near 100 to around 60 megatonnes per year. This is meaningful progress for reducing the country's warming impact, but sustaining and accelerating the decline in agriculture remains the most effective path to further cut national nitrous oxide emissions.
Background
The chart shows a national breakdown by source of the yearly nitrous oxide (N2O) emissions from human activities and processes, expressed as weight in megatonnes (Mt). Human-induced emissions are the main driver of the increasing atmospheric nitrous oxide that is warming our planet. The sources of human nitrous oxide emissions are
- Agriculture
- Energy
- Industry
- Waste
- Other
Agriculture
Emissions related to agriculture are mainly from the use of synthetic fertilizers and manure management.
Synthetic fertilizer, used for agricultural processes, contains a lot of nitrogen. That nitrogen in the soil reacts and causes considerable N2O emissions. The use of excess fertilizer, meaning more fertilizer than the plants can use to grow, causes even higher relative emissions. Applying the right amount of fertilizer at the right time can reduce N2O emissions. There are many technical solutions to reduce emissions while keeping, or even increasing, agricultural yields.
When manure is left on the field or otherwise managed in dry processes, it emits considerable amounts of nitrous oxide. Manure can be managed by wet processes, which reduces nitrous oxide emissions but increases methane emissions. Some technical solutions focus on modifying the animal feed to reduce the nitrogen in the manure, thereby reducing nitrous oxide emissions.
Energy, Industry, Waste, and Other
All non-agricultural categories together have much lower emissions than agricultural emissions alone.
N2O emissions related to energy are almost all from the combustion of fossil fuels. For example, the combustion of fossil fuels in power plants, cars, and airplanes not only causes CO2 emissions but also emits nitrous oxide (N2O). Any advances to reducing fossil fuel dependency will thus also reduce nitrous oxide emissions.
Most industry-related emissions are from the chemical industry for producing fertilizer, nylon, and similar products. Technologies are available to reduce emissions in these processes.
Nitrous oxide emissions from waste come from, for example, wastewater treatment and landfills.
Wikipedia: Nitrous oxideIPCC: AR6, 5.16 Anthropogenic nitrous oxide (N2O) emissions
Units and Measures
N2O emissions are expressed in the total weight in megatonnes per year. 1 Megatonne is equal to 1 million tonnes.
Wikipedia: MegatonneWikipedia: Global warming potential
About the Data
The last available year in all the emission datasets is 2023. N2O emissions come from the PRIMAP-Hist dataset. It is a rich dataset that combines several published sources to create a historical emissions time series for various greenhouse gases.
The Key Insights paragraph was created using a large language model (LLM) in combination with our data, historic events, and a structured approach for best accuracy by separating the context generation from the interpretation and narrative.
Data Sources
PRIMAP-hist The PRIMAP-hist national historical emissions time series (1750-2023)
Update cycle: Every few monthsDelay: Less than 1 yearCredits: Gütschow, Johannes; Busch, Daniel; Pflüger, Mika (2024): The PRIMAP-hist national historical emissions time series (1750-2023) v2.6. Zenodo.