A greenhouse gas emission inventory is a compilation of historical greenhouse gas emissions from sources, such as transport, power generation, industry and agriculture, from 1990 to the most recent year for which data is available.

A greenhouse gas emission projection is an estimate of what emission levels are likely to be in the future. They are based on key assumptions such as economic growth, fuel prices and Government policy.

Essentially the inventory data provides a summary of past emissions whereas the projections attempt to estimate the emissions in the future.

National Emission Inventories; The United Nations Framework Convention on Climate Change (UNFCCC) and its Kyoto Protocol provide the basis for international action to address climate change. Parties to the convention and its Kyoto Protocol are committed to developing and publishing the national emission inventories of greenhouse gases (GHGs) which is a key element of assessing progress towards meeting commitments and targets.

The EPA compiles Ireland's national greenhouse gas emission inventory on an annual basis. This inventory is submitted to the European Commission and UNFCCC each year by 15 January and 15 April respectively.

Emissions data for the following gases is reported on an annual basis: carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulphur hexafluoride (SF₆), and nitrogen trifluoride (NF₃).

Emissions are classified into the ten following sectors; agriculture, transport, energy industries, residential, manufacturing combustion, industrial processes, F-gases, waste, commercial services and public services.

Greenhouse gases other than CO₂ (i.e. methane, nitrous oxide and F-gases) may be converted to CO₂ equivalent using their global warming potentials (GWPs). The GWP of a gas is a measure of the cumulative warming over a specified time period usually 100 years, by a unit mass of this gas. This is expressed relative to carbon dioxide (CO₂) which has a GWP of 1. The mass emission of any gas multiplied by its GWP gives the equivalent emission of the gas as carbon dioxide. This is known as CO₂ equivalent. This makes it possible to sum up the emissions and contribution of Greenhouse Gas (GHG) to climate change and determine options to address climate change.

These gases comprise HFCs (hydrofluorocarbons), PFCs (perfluorcarbons), SF₆ (sulphur hexafluoride) and NF₃ (nitrogen trifluoride). They are much more potent than the naturally occurring greenhouse gas emissions (carbon dioxide, methane and nitrous oxide).

Global warming potential of greenhouse gases in the inventories and projections;

Carbon dioxide (CO2) GWP = 1

Methane (CH4) GWP = 28

Nitrous oxide (N2O) GWP = 265

Hydrofluorocarbons (HFCs) GWP = 4 to 12,400

Perfluorinated compounds (PFCs) GWP = 6630 to >17,400

Sulphur hexafluoride (SF6) GWP = 23,500

Nitrogen trifluoride (NF3) GWP = 16,100

The mass emission of any gas multiplied by its GWP gives the equivalent emission of the gas as carbon dioxide. This is known as CO₂ equivalent. This makes it easier to sum up the emissions and contribution of Greenhouse Gas (GHG) to climate change and determine options to address climate change.

On 14th May 2018, the European Council adopted a regulation (EU 2018/842 – the Effort Sharing Regulation) on greenhouse gas emission reductions. The regulation sets out binding emission reduction targets for member states in sectors falling outside the scope of the EU emissions trading system for the period 2021-2030. In April 2023 the Effort Sharing Regulation was amended (EU 2023/857) and Ireland’s new 2030 target under the Effort Sharing Regulation is to limit its greenhouse gas emissions by at least 42% by 2030.

Annual emission limits out to 2025 for the 42% reduction were set by the EU in 2023, with set limits out to 2030 published in Commission Implementing Decision (EU) 2026/895 of 24 April 2026 amending Implementing Decision (EU) 2020/2126.

Million tonnes (Mt) CO2eq =1,000 kilotonnes

1 kilotonne=1,000 tonnes

EU greenhouse gas emission targets and reduction obligations for Ireland are split into two broad categories.

The first category covers the large energy and power (i.e. energy intensive) industry which are controlled under the EU Emissions Trading System. Emissions from this category are referred to as “ETS emissions”.

The second category deals with the non- EU Emissions Trading System sectors such as agriculture, transport, residential, commercial, waste and non-energy intensive industry.  Emissions from this category are under the scope of the EU’s Effort Sharing Regulation (ESR) and are referred to as “Non-ETS emissions”.

Land use, land-use change, and forestry (LULUCF), also referred to as forestry and other land use (FOLU), is defined by the United Nations Climate Change Secretariat as a "greenhouse gas inventory sector that covers emissions and removals of greenhouse gases resulting from direct human-induced land use such as settlements and commercial uses, land-use change, and forestry activities." It covers the following categories forest land, cropland, grassland, wetlands, settlements, other land and harvested wood products.

Reporting of the LULUCF sector

The UNFCCC reporting guidelines on annual inventories for Parties included in Annex I to the Convention (Decision 24/CP.19)provide guidance on the estimation and reporting of anthropogenic emissions by sources and removals by sinks of greenhouse gases not controlled by the Montreal Protocol caused by activities relating to land use, land use change and forestry. The guidance stipulates that reporting under the UNFCCC covers all anthropogenic emissions and removals from the lands included in the LULUCF sector (land-based approach). In principle, this approach applies a wall-to-wall comprehensive inventory of anthropogenic sources and sinks of greenhouse gases over the land units subject to activities relating to land use, land use change and forestry.

The EPA greenhouse gas projections are not a forecast but are an estimate of what emissions are likely to be if a specific set of policies and measures are implemented over a defined period of time (e.g. from 2025 to 2030). Two scenarios are considered by the EPA in line with reporting guidelines, the With Existing Measures (WEM) scenario and the With Additional Measures (WAM) scenario.

The WEM scenario is a projection of future emissions based on the measures currently implemented and actions committed to by Government. To become part of the WEM scenario a policy or measure must be in place by the end ofthe latest inventory year and, in parallel, the resources and/or legislation must be in place or committed to by Government Departments or Agencies. The WAM scenario is a projection of future emissions based on implemented measures included in the WEM scenario plus additional planned measures that are under discussion (as per plans, programmes or other policy documents) and have a realistic chance of implementation in the future.

Further information on the policies and measures for the individual sectors that are included in both With Existing Measures and With Additional Measures scenarios in the emissions projections is available in the latest Ireland’s Greenhouse Gas Emissions Projections Report.

The data submitted in the current year is the inventory for x-2 years so for example in 2022 the EPA submitted to the EU and UNFCCC, the 1990-2020 time series. All reports and infographics are based on the 1990-x-2 timeseries and the most recent year of data. A provisional estimate of emissions is produced in quarter four of the year before submission and the website will be updated with this provisional data as soon as it is available.

Decarbonisation means reduction of carbon. What is meant is the conversion to an economic system that sustainably reduces and compensates the emissions of carbon dioxide (CO₂). The long-term goal is to create a CO₂-free global economy.

A low-carbon economy, low-fossil-fuel economy, or decarbonised economy is an economy based on low-carbon power sources that therefore has a minimal output of greenhouse gas emissions into the atmosphere, specifically carbon dioxide. A low-carbon economy is simply an economy that causes low levels of GHG emissions compared with today's carbon-intensive economy. 'Carbon' refers to carbon dioxide, the GHG, which contributes the most to climate change. The low-carbon economy can be seen as a step in the process towards a zero-carbon economy.

The EPA incorporates the latest scientific information, including on new technologies, in the National Greenhouse Gas Inventories and Projections. This arises through the adoption of new international guidelines on inventory compilation and from national and international research.

In introducing new science and improvements to the inventories, the EPA follows the principles set out in the emission inventory guidelines set out by the Intergovernmental Panel on Climate Change (greenhouse gas emissions)[1],[2] and European Monitoring and Evaluation Programme/European Environment Agency (air pollutants)[3]. Some of the key principles that the EPA follows include:

• Ensuring measurement data covers a representative sample and that suitable measurements have been used.
• Preferring the use of measurement methods developed by official standards organisations and field-tested to determine their operational characteristics.
• Developing Ireland specific emission factors for key categories, with the goal to improve the accuracy of relevant emissions and removals estimates.
• Verifying that emission factors derived from direct measurement are representative of Ireland's circumstances.
• Referencing peer-reviewed, published literature relevant to Ireland's circumstances as this should provide the most accurate representation of practices and activities.

As part of both international reporting obligations and continuous improvement processes, Ireland’s national inventories are reviewed annually by both the EU and the UN. Recommendations arising from these reviews [4] allow the identification and prioritisation of national greenhouse gas and air pollutant emission research. Subsequently, research projects funded by both the EPA and other public bodies, with associated national and international technical committee participation by the EPA’s Emission Statistics Team, ensure the increasing robustness of emissions estimation.

[1] https://www.ipcc-nggip.iges.or.jp/public/2019rf/pdf/1_Volume1/19R_V1_Ch02_DataCollection.pdf

[2] https://www.ipcc-nggip.iges.or.jp/public/2019rf/pdf/1_Volume1/19R_V1_Ch04_MethodChoice.pdf

[3] https://www.eea.europa.eu/publications/emep-eea-guidebook-2023/part-a-general-guidance-chapters

[4] Latest UNFCCC review report: https://unfccc.int/process-and-meetings/transparency-and-reporting/reporting-and-review-under-the-convention/greenhouse-gas-inventories-annex-i-parties/inventory-review-reports-2022

Environmentally, there are two key benefits to using urease inhibited (or ‘stabilised’) fertiliser products:

1. the reduction of emissions of ammonia, an important air pollutant, when compared to the use of ‘straight’ urea;
2. when used as a replacement for Calcium Ammonium Nitrate (CAN), a reduction in nitrous oxide emissions, a potent greenhouse gas.

As outlined in the international guidelines for national inventories and projections (FAQ: How are national inventories updated with the latest science?), research should be conducted at field scale, covering a range of soil types and environmental conditions so that efficacy of any particular product is demonstrated at field level under the conditions in which it will be used.

The following fertiliser products have met the criteria for inclusion as urease inhibitor products within the national greenhouse gas and air pollutant Inventories and Projections 1990-2022:

• N-(n-butyl)-thiophosphoric triamide (NBPT)
• N-(n-propyl)-thiophosphoric triamide (NPPT)
• N-(n-butyl)-thiophosphoric triamide (NBPT) + N-(n-propyl)-thiophosphoric triamide (NPPT)
• N-(2-nitrophenyl) phosphoric triamide (2NPT)

The most relevant national research demonstrating efficacy at field level (Forrestal et al. 2016 [1]; Harty et al., 2016 [2]; Roche et al., 2016 [3]) provide the evidence base for the inclusion of these products. 2NPT’s mode of action is similar to that of NBPT, however, to date it’s use in Ireland has been minor.

If/when information is provided on new products that meet the criteria specified these products will be added to the list above. The emission or abatement factor is applied from the time the product was placed on the Irish market and retrospectively across the time series in instances where a product has been on the market prior to provision of supporting evidence. In the absence of robust scientific evidence then the emission factor for straight urea is applied.

[1] https://doi.org/10.1111/sum.12232

[2] https://doi.org/10.1016/j.scitotenv.2016.04.120

[3] https://doi.org/10.1016/j.agee.2016.08.031