Emissions of CO2 accounted for 63.5 per cent of the total (excluding LULUCF) of 60,506.90 kt CO2 equivalent in 2018, with CH4 and N2O contributing 23.1 per cent and 11.5 per cent, respectively. The combined emissions of HFC, PFC, SF6 and NF3 accounted for 1.8 per cent of total emissions in 2018. In 1990 emissions of CO2, CH4, N2O and the combined emissions of HFCs, PFCs, SF6 and NF3 accounted for 59.3, 26.6, 14.0 and less than 0.1 per cent, respectively of total emissions of 55,423.85 kt CO2 equivalent.
Carbon dioxide CO2 is the most significant contributor to the greenhouse gas emissions with Energy Industries and Transport sectors responsible for 26.3 per cent and 31.4 per cent of total CO2 emissions (excluding LULUCF) in 2018, respectively. Residential has a 15.7 per cent share, Manufacturing Combustion has an 12.3 per cent share and the remainder of CO2 emissions (14.3 per cent share) fall into other categories. Emissions of CO2 increased from 32,887.18 kt in 1990 to 38,444.64 kt in 2018, which equates to an increase of 16.9 per cent. The main driver behind this increase in emissions is fuel combustion in Transport (+139.8%) over the period 1990-2018.
Carbon Dioxide Emissions by sector 1990-2018
Methane CH4 Methane is the second most significant contributor to greenhouse gas emissions in Ireland which is due to the large population of cattle.
In 2018 emissions of CH4 were 14,004.60 kt CO2eq, indicating a decrease of 5.1 per cent on the 1990 level of 14,760.96 kt CO2 equivalent. Emissions of CH4 increased progressively from 1990, reaching a peak in 1998 of 15,441.5 kt CO2eq, which reflects an increase in livestock numbers and therefore increased emissions from source categories Enteric Fermentation and Manure Management. Between 1998 and 2011 CH4 emissions decreased due to falling livestock numbers from reforms of the Common Agricultural Policy (CAP). The main contributor to the CH4 trend has been Agriculture and in 2018 the sector accounted for 92.6 per cent of the total CH4 emissions (compared to 86.5 per cent share in 1990 when emissions from Waste sector had a larger share in the level). The sectoral CH4 emissions from Agriculture increased by 1.6 per cent between 1990 (12,764.3 kt CO2 equivalent) and 2018 (12,971.2 kt CO2 equivalent).
Another significant source of CH4 emissions is Waste sector, especially from landfill gas in Solid Waste Disposal on Land. CH4 emissions from Waste decreased from 9.4 per cent share of total methane emissions (1,380.01 kt CO2eq) in 1990 to 5.4 per cent share (757.9 kt CO2eq) in 2018. This decrease is a result of improved management of landfill facilities, including increased recovery of landfill gas utilised for electricity generation and flaring.
Methane (CH4) emissions by sector 1990-2018
Nitrous oxide N2O emissions decreased by 10.0 per cent from their 1990 level of 7,741.1 kt CO2eq in 1990 to 6,969.6 kt CO2eq in 2018. Like CH4, emissions of N2O increased during the 1990s to reach peak level of 8,531.2 kt CO2eq in 1998 reflecting increased use of synthetic fertilisers and increased amounts of animal manures associated with increasing animal numbers over that period. Emissions of N2O subsequently show a clear downward trend following reductions in synthetic fertiliser use and organic nitrogen applications on land because of CAP reform on animal numbers as well the closure of Ireland’s only nitric acid plant in 2002. However, the last 3 years N2O emissions are increasing again, as the dairy sector expands, and nitrogenous fertiliser use increases.
The largest contributor to the trend is the Agriculture sector with 93.4 per cent share of the total N2O emissions (6,508.5 kt CO2eq) in 2018. This reflects an increase from 83.4 per cent share (6,450.7 kt CO2eq) in 1990. Emissions from Industrial Processes chemical industry used to be the second largest contributor to the trend contributing 13.3 per cent to total N2O emissions in 1990 and an average of 10.5 per cent share to the trend between 1990 and 2000, before falling to 4.4 per cent share in 2002 – the year of nitric acid plant closure.