Global Warming Potentials
The CAT uses Global Warming Potential (GWP) values from the IPCC’s Fourth Assessment Report (AR4) for all figures and time series. Assessment completed prior to December 2018 (COP24) used GWP values from the IPCC’s Second Assessment Report (SAR).
Singapore provided a national greenhouse gas inventory for 1994, 2000, 2010, 2012, and 2014, and emissions projections for 2020 for a business as usual (BAU) scenario in the Third Biennial Update Report (National Environment Agency, 2018). Data for emissions in between the years reported was calculated using linear interpolation. CAT converted the HFCs and PFCs to AR4 GWP values from the Third Biennial Update Report and assumed the same percentage for previous years. For emissions between 1990 and 1993, we have applied growth rated from the PRIMAP database to the reported historical emissions in 1994 (Gütschow et al., 2019).
Singapore is a city-state with one of the highest population densities in the world and is nearly completely dependent on imports for food. Most of the remaining natural areas are sanctuaries. We therefore do not consider emissions related to LULUCF sector for the analysis, as they are negligible.
Pledges and targets
For the 2020 emissions target we use the business-as-usual (BAU) emissions projected in 2020 according to the National Climate Change Strategy – 77.2 MtCO2e in 2020 – and apply target reduction rates directly (National Climate Change Secretariat, 2012). Given that the Global Warming Potential used for the BAU scenario is not specified, we assume this level to be AR4 GWP.
Singapore’s updated NDC provides an absolute emissions level (65 MtCO2e) for 2030 in AR5 GWP. We convert the AR5 GWP to AR4 GWP (65 MtCO2e) using a ratio, where the results match the calculation of the emissions intensity target specified in the updated NDC (36% reduction of emissions intensity below 2005 levels by 2030). These calculations include NF3 gas, in line with the NDC updated gas coverage. The Singapore Government has not yet reported NF3 gas levels, so our calculations use data from US EPA (2019).
For Singapore’s First NDC, we used the target emissions levels reported in the First NDC, where it is clarified that to achieve the 2030 emissions intensity level, Singapore’s emissions are expected to stabilise at around 65 MtCO2e based on current projected growth. We converted this target from SAR to AR4 GWP by assuming the same GDP for 2030 (578.020 million SGD in 2030 based on target emissions levels and emissions intensity) and calculating new emissions intensities based on inventory data converted to AR4 GWP, which moves up the 2030 target to 68 MtCO2e. However, GDP assumptions change between the first NDC and the updated NDC, demonstrating how unclear and problematic emissions intensity targets can be. When applying the same approach as for the first NDC, calculating the implicit GDP assumption underlying the updated NDC (based on the updated NDC noting that “based on current projections” the NDC target will allow Singapore to “achieve a 36% reduction in emissions intensity (EI) from 2005 levels by 2005”, there is no difference in ambition level between the old and new NDC targets.
Current policy projections
Our current policy emissions pathway relies on energy related CO2 emissions projections of the 7th edition of the energy outlook of the Asia Pacific Energy Research Centre (APERC, 2019a) and on non-CO2 projections from the United States Environment Protection Agency (U.S. Environmental Protection Agency, 2019). Given that both sources present differences with historical values reported in the emissions inventory, we harmonise with historical values by applying growth rates from the projections to the last reported year (2014).
Since APERC’s energy outlook includes projections only for energy related CO2 emissions, for our current policy pathway we assume that non-energy related CO2 emissions will remain constant for the whole projection period at the last historical data level available, corresponding to 2010 (IEA, 2014). This assumption is done due to lack of projections for this type of emissions and taking into account their small and decreasing share in total emissions (4% in 1990 and 1% from 2005 to 2010).
We excluded emissions from marine and aviation bunkers when calculating the comparability range which determines the rating. These emissions are nearly three times higher than the rest of Singapore's emissions—with the great majority being related to Singapore’s role as a hub in international shipping.
We applied a novel method to estimate the COVID-19 related dip in greenhouse gas emissions. The uncertainty surrounding the severity and length of the pandemic creates a new level of uncertainty for current and future greenhouse gas emissions. We first updated the current policy projections as described above. We then distil the emission intensity (GHG emissions/GDP) from this pre-pandemic scenario and apply to it most recent GDP projections that take into account the effect of the pandemic.
The pre-pandemic emissions intensity (GHG emissions/GDP) is based on historical International Monetary Fund (IMF) data to 2015 and APERC GDP growth rates assumed thereafter (APERC, 2019b; IMF, 2015). The emissions intensity was then applied to a range of GDP scenarios that incorporate COVID-19’s impact on Singapore’s economy. In May 2020, The Singapore Ministry of Trade and Industry (MTI) forecasted a drop in GDP growth of -4 to -7 percent in 2020 (MTI, 2020). We also compared the International Monetary Fund (IMF) GDP growth scenario as an alternative source (IMF, 2020). The IMF forecasted a -3.5 percent drop in GDP growth 2020 and 3% growth in 2021 (IMF, 2020). The MTI -4% forecast and IMF -3.5% forecast produced similar results, although the MTI forecast results in larger emissions reductions in 2020, in 2030 there is only a 0.1 MtCO2e difference. The CAT uses the Singapore MTI forecast of -7% and the IMF -3.5% to provide a range of emissions. The CAT uses the IMF over the MTI -4% forecast as it incorporates a projection for GDP growth for 2021 (the Singapore MTI only provides GDP estimates for 2020).
The emissions intensity for 2020 (and 2021 based on the IMF forecast) are derived from the COVID-19 scenarios. The CAT applies the growth rates of the pre-pandemic emissions intensity from 2021/2 to 2030. The CAT calculates the emissions from the emissions intensity inclusive of COVID-19 impacts to 2030, and then applies the growth rates from the pre-pandemic current policy emissions scenario to extend the emissions data to 2050.