Their results are summarised in Table 4.3. All but one of the models analysed (25 out of 26) assumed atmospheric concentrations of GHGs between 525 and 650 ppm in 2050, which is, of course, considerably higher than the 450 ppm or lower implied in the Paris Agreement. This may be taken as an indicator of the extent to which the policy debate has abandoned any link with modelling efforts attempting to estimate realistic medium-range scenarios. It should also be noted that the models considered calculate abatement costs for the energy sector rather than for the electricity sector. In principle, this would correspond to the level of the carbon tax required. Ppm: parts per million.