The impact of the most effective current and planned policies on greenhouse gas emissions up to 2030 has been projected by the NewClimate Institute, IIASA and PBL (Nascimento et al., 2021; Den Elzen et al., 2016b). Current and planned policies were selected on the basis of literature research and expert knowledge. Experts involved in the CD-LINKS, COMMIT, and ENGAGE projects reviewed the full list of policies, after which a shortlist was compiled of those expected to have the greatest impact on greenhouse gas emissions, for further quantification. The calculations by NewClimate Institute were largely based on its analyses for the Climate Action Tracker project, jointly carried out with Climate Analytics (CAT, 2021). For the calculation, existing scenarios from national and international studies were used, as well as NewClimate Institute’s own calculations of the impact of individual policies in various sub-sectors. PBL based their calculations for the current policies scenarios (all sectors, except land use) on the IMAGE model; IIASA’s projections (the land-use sector only) were based on their global land-use model GLOBIOM and global forest model G4M. Basis of the PBL calculations of the impact of climate policies is the SSP2 baseline (no climate policy), as implemented in the IMAGE model (Van Vuuren et al., 2017; Roelfsema et al., 2020). Current climate and energy policies in G20 countries, as identified in the CD-LINKS, COMMIT, and ENGAGE project, were added to that baseline. For countries that are part of a larger IMAGE region (Australia, Kazakhstan, Republic of Korea, Russian Federation, and Ukraine), emissions projections were downscaled using the country’s share in the region’s 2015 emissions as a constant scaling factor.
In this update we also assess the effect of COVID-19 on GHG emissions projections. NewClimate emissions estimates including the effect of COVID-19 assume that emissions intensity over GDP remains the same as it would under current policies excluding the effect of COVID-19 and that the reduction in emissions is induced by a slowdown in GDP growth.
Land-use change accounting method: Most of the 25 analysed countries and many of the remaining countries report emission target levels that include CO2 removals from activities related to the land use, land use change and forestry (LULUCF) sector. Although there are uncertainties concerning which accounting approaches and methodologies countries will apply to account for LULUCF related emissions and removals, we assume that a majority of countries will apply the net-net accounting approach, so land use emissions are included in the same way as the emissions from the other sectors (see Nascimento et al., 2021).
Quantification of the NDCs is described, in detail, in Den Elzen et al. (2016), and the quantification of the land-use targets in the NDCs is described, in detail, in Grassi et al. (2017) and Forsell et al. (2016).