Implementation

Abstract

This chapter provides an overview of reductions in the emission of greenhouse gases (GHGs) that will be needed to achieve either the target (1.5 °C warming) or upper limit (2.0 °C warming) of the Paris Climate Agreement. We quantify how much energy must be produced, either by renewables that do not emit significant levels of atmospheric GHGs or via carbon capture and sequestration (CCS) coupled to fossil fuel power plants, to meet forecast global energy demand out to 2060. For the Representative Concentration Pathway (RCP) 4.5 GHG emission trajectory to be matched, which is necessary for having a high probability of achieving the Paris target according to our Empirical Model of Global Climate (EM-GC), then the world must transition to production by renewables of 50 % of total global energy by 2060. For the RCP 2.6 GHG emission trajectory to be matched, which is necessary to achieve the Paris upper limit according to general circulation models (GCMs), then 88 % of the energy generated in 2060 must be supplied either by renewables or combustion of fossil fuels coupled to CCS. We also quantify the probability of achieving the Paris target in the EM-GC framework as a function of future CO2 emissions. Humans can emit only 82, 69, or 45 % of the prior, cumulative emissions of CO2 to have either a 50, 66, or 95 % probability of achieving the Paris target of 1.5 °C warming. We also quantify the impact of future atmospheric CH4 on achieving the goals of the Paris Climate Agreement.