Figure 1.26 | Historical and projected future concentrations of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) and global mean temperatures (GMST). GMST temperature reconstructions over the last 2000 years were compiled by the PAGES 2k Consortium (2017, 2019) (grey line, with 95% uncertainty range), joined by historical GMST time series assessed in Chapter 2 (black line) – both referenced against the 1850–1900 period. Future GSAT temperature projections are from CMIP6 ESM models across all concentration-driven SSP scenario projections (Chapter 4). The discontinuity around year 2100 for CMIP6 temperature projections results from the fact that not all ESM models ran each scenario past 2100. The grey vertical band indicates the future 2015–2300 period. The concentrations used to drive CMIP6 Earth system models are derived from ice core, firn and instrumental datasets (Meinshausen et al., 2017) and projected using an emulator (Cross-Chapter Box 7.1; Meinshausen et al., 2020). The colours of the lines indicate the SSP scenarios used in this Report (Cross-Chapter Box 1.4, Figure 1). Further details on data sources and processing are available in the chapter data table (Table 1.SM.1).