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. Assessments completed prior to December 2018 (COP24) used GWP values from the IPCC’s Second Assessment Report (SAR).
Historical emissions data were obtained from the UNFCCC GHG inventory and cover the period to 2017 (Government of New Zealand, 2019a).
Target emissions levels were calculated from the national inventory data published in the 2019 CRF data submitted to the UNFCCC. The target for 2020 is calculated using the information provided in the 2018 net position update, which confirmed that New Zealand is projected to meet its unconditional target to reduce emissions to 5% below 1990 levels by 2020 with a surplus of 92.4 million units, by making use of 31.4 million available units from CP1 (out of a total surplus of 123.7 million units) to meet its 2020 target, where one unit represents one tonne of greenhouse gas emissions as carbon dioxide equivalent (tCO2eq) (Ministry for the Environment, 2018a). The 2019 net position update shows a surplus of 96.8 million units, meaning that 27 million units would be used to meet its 2020 target (Ministry for the Environment, 2019).
When describing its NDC target, New Zealand states that the 30% reduction below 2005 levels is equivalent to a reduction of 11% from 1990 levels. This equivalence is only possible if gross emissions (excluding LULUCF) are used in the base years (1990 and 2005). For the target year however, New Zealand clarifies that its target is economy wide and covers all sectors, including LULUCF. This suggested approach that excludes LULUCF emissions in the base year but includes them in the target year is known as “gross-net” approach. For illustrative purposes, we have estimated the emissions levels using both a gross-net and a net-net approach.
For the 2030 target, we have additionally estimated the potential impact of the carryover of Kyoto Protocol forestry activity credits in the CP1 and CP2. For this, we have used the numbers provided in the 2018 net position update for CP1 and estimated the surplus that would result in CP2 under current policy projections. We assume that the cumulative surplus credits would be distributed between 2020 and 2030 using a linear extrapolation.
The 2050 Long-Term Target has been quantified using projected LULUCFs emissions for 2050 based on the latest target analysis taken from four different scenarios presented in the Regulatory Impact Statement (Ministry of the Environment, 2019). The four scenarios model a spitted target based on an emissions reduction of biogenic methane together with a net-zero target by 2050 of all greenhouse gases emissions excluding biogenic methane. The lower end is based on the higher sink from the estimated LULUCFs projections added to the remaining biogenic methane emissions after a 47% emissions reduction by 2050. The higher end is based on the lowest sink from the estimated LULUCFs emissions projections added to the remaining biogenic methane emissions after a 24% emissions reduction by 2050.
Current policy projections
The current policy projections are based on the “with measures” scenario of the 3nd Biennial Report of New Zealand, harmonised on the latest historical data 2017 (Ministry for the Environment, 2017b). The ‘with measures’ scenario includes the effects of key quantifiable policies and measures currently implemented. Specifically, it includes the New Zealand Emissions Trading Scheme; ENERGYWISE; the Warm Up New Zealand: Healthy Homes 2013–2018 programme; the Efficient Products Programme; the Large Energy User Programme; Commercial buildings programmes; the Vehicle fuel economy labelling; the Permanent Forest Sink Initiative; the Erosion Control Funding Programme; the Sustainable Land Management Hill Country Erosion Programme; the Afforestation Grant Scheme; and the Waste Minimisation Act 2008.