Climate sensitivity values above 5 °C, such as 8 °C or more, cannot be ruled out, which would shift the estimated temperature increases for existing emission levels even higher (Meinshausen et al. The concentration of C02 alone is projected to be around 530 ppm in 2050 and 780 ppm in 2100 (Figure 3.9). The Outlook Baseline scenario suggests that these GHG-concentration levels would lead to an increase in global mean temperature at the middle of the century of 2.0 °C-2.8 °C, and 3.7 °C-5.6 °C at the end of the century (compared to pre-industrial times).