The GHG emissions projections were harmonised with historical 1990–2017 emissions. For most Annex I countries, the historical emissions data is based on the Greenhouse Gas Inventories submitted in 2019 to the UNFCCC (UNFCCC, 2019a). For many non-Annex I countries, the historical data was taken from the national reports (National Communications and Biennial Update Reports) (UNFCCC, 2019b, UNFCCC, 2019c) (when available), EDGAR database (Olivier and Peters, 2019) (GHG emissions excluding land-use) and FAOSTAT (2020) data (land-use emissions) (for details for the 25 major emitting countries, see Kuramochi et al., 2019). GHG emissions projections under current policies were harmonised to the latest historical emissions data. The harmonisation year was changed to 2017 for Annex I countries and the latest data year for non-Annex I countries.
All GHG emission figures are expressed using the 100-year global warming potentials (GWPs) from the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report. Since Kuramochi et al. provide GHG emissions projections for 12 of the 25 countries (i.e. Argentina, Brazil, China, Colombia, India, Indonesia, Mexico, Morocco, Republic of Korea, Saudi Arabia, South Africa and Thailand), using GWPs from the IPCC Second Assessment Report and Fifth Assessment Report, we converted them into IPCC AR4 GWP terms by applying conversion factors (range: 1.01 to 1.03) derived from the national inventories. This allows for a direct comparison of current policies scenario and NDC projections between countries. However it implies that the target emission levels shown can be somewhat different from the official target emission levels reported by the national governments that are provided in terms of GWPs specified in the NDC documents. For most countries, emission projections encompass all greenhouse gas emissions, including those from land use, land-use change and forestry.
To calculate per capita and per GDP indicators, we used the population projections from the UN World Population Prospects 2019 (UN DESA, 2019) and GDP projections from the OECD long-term forecast (OECD, 2018), supplemented with the projections underlying the IMAGE SSP2 scenario. The historical data from 1990 to 2018 on GDP (in PPP) and population was based on the IEA dataset (World Energy Indicators).
The emission projections based on the NDCs and current policies can be found in Den Elzen et al. (2016) and Kuramochi et al. (2019). If you plan to use these data in official publications, please