Tonga's Sources of N2O Emissions
Key Insights
Agriculture Shapes The Long Trend
Tonga's nitrous oxide profile has been dominated by agriculture, contributing around four-fifths of emissions. From the post-war era into the late 1970s, agriculture rose from near-zero to roughly 0.02 megatonnes per year. Since then, it has been broadly stable, fluctuating within a narrow band around the high teens of thousandths of a megatonne, indicating a long period of steady but elevated levels.
Minor Sectors, Modest Increases
Non-agricultural sources remain small by comparison. Energy was negligible until the late 1970s, grew through the 1980s and early 1990s, and has largely leveled off at very low levels (around a few thousandths of a megatonne). Waste and other sources emerged from near-zero between the 1960s and 1990s and have inched upward, remaining low at roughly 0.001-0.002 megatonnes. Industry is minimal and steady throughout, adding little volatility to the national picture.
Current Trajectory And Priorities
Overall, emissions are stable, with agriculture steady near 0.02 megatonnes and waste and other contributing small shares just over 5% each. To reduce Tonga's warming impact, the biggest opportunity is to bend the dominant agricultural line downward, while keeping the gentle rise in waste and other from adding incremental increases. Sustained attention to these sectors would shape the national trajectory most.
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.