151to 2060 using linear fits. This extrapolation is conducted because successful imple-
mentation of the Paris Climate Agreement will require wholesale transformations in
how energy is produced by year 2060.
Figure 4.2b compares the EIA projection of emissions of CO 2 from combustion
of coal, natural gas, and liquid fossil fuels needed to meet global energy consump-
tion (colored wedges) to emissions of CO 2 from RCP 4.5 and RCP 8.5 (lines).
Again, the EIA estimates extend only to 2040. We have also extrapolated the EIA
emission estimates to 2060, for reasons that will soon become apparent. For sim-
plicity, we assume that renewables denote a means of producing energy for which
atmospheric release of GHGs is negligible. At the end of this section, potential fal-
lacies of this assumption for renewables are presented. We also assume nuclear
energy poses no significant burden to atmospheric GHGs.
Figure 4.2b shows that if the world follows a business as usual approach, emissions
of CO 2 from the combustion of fossil fuels will fall between RCP 4.5 and RCP 8.5.
The EIA projections are based on forecasts of demand, availability of various tech-
nologies, and market forces. There is no attempt to meet any particular climate change
goal in this EIA forecast. The good news, we suppose, is that market forces, perhaps
combined with environmentalism that acts through the market, appear to be driving
the world away from RCP 8.5. The bad news, however, is that the gap between pro-
jected emissions of CO 2 and RCP 4.5 is significant in 2040, and grows thereafter.
Figure 4.3 illustrates the dramatic transformation that will have to occur for emis-
sions of CO 2 to follow RCP 4.5 (Thomson et al. 2011 ) over the 2030–2060 time period.
Implicit in the calculations throughout this chapter is the assumption that EIA energy
demand projections are met (see Methods for detailed description of how the calcula-
tions are conduced). Figure 4.3a shows that for RCP 4.5 CO 2 emissions to be met, the
world must place itself on a trajectory whereby half of its energy needs: that is, half of
all energy used for industry, transportation, heat, electricity, etc., will be realized by
renewables that emit little to no GHGs by year 2060. All of the analyses in this chapter
extend to 2060 because, quite simply, unless the world soon places itself on this trajec-
tory, it will not be possible to keep global emissions of CO 2 below those of RCP 4.5.
The EIA energy demand forecast is, interestingly, quite similar to that used in the
design of RCP 4.5. The four circles in Fig. 4.3a show energy estimates given in
Fig. 4.4a of Thomson et al. ( 2011 ). While development of energy produced by
renewables was an important component of the original RCP 4.5 design, their pro-
jection has energy from hydropower, solar, wind, plus geothermal being only ~32 %
of the global energy total by end of century.
The reason our projection for the energy share from renewables, 50 % by 2060, dif-
fers so much from the RCP 4.5 projection of 32 % by 2100 can be summarized in one
word: Fukushima. The Thomson et al. ( 2011 ) paper was submitted during September
2010 and was likely in its final stage of review at the time of the Fukushima Daiichi
nuclear power plant accident, which occurred during early March 2011. Their RCP 4.5
design included a sizeable slice for growing energy demand to be met by expansion of
nuclear energy. Our projections for 2060, on the other hand, rely on extrapolation of the
latest EIA projection of nuclear energy from 2030 to 2040. By 2060, nuclear energy is
4.2 World Energy Needs