Paris Climate Agreement Beacon of Hope

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Unless society is able to soon implement provision of electricity, transportation, heat,
and industrial energy on a massive, global scale that releases little or no GHGs to the
atmosphere, we are on a course where the world will experience dire effects of climate
change (Lynas 2008 ).
In this chapter we provide a quantitative analysis of the transformation of energy
production that must be put in place for successful implementation of the Paris
Climate Agreement. Global warming projections based on the atmospheric, oceanic
general circulation models (GCMs) that participated in Climate Model
Intercomparison Project Phase 5 (CMIP5) (Taylor et al. 2012 ) indicate that achieving
Paris Climate Agreement upper limit of 2 °C warming will require GHG emissions
to follow the Representative Concentration Pathway (RCP) 2.6 trajectory (van
Vuuren et al. 2011 ; Rogelj et al. 2016a). We consider both RCP 2.6 (van Vuuren et al.
2011 ) and RCP 4.5 (Thomson et al. 2011 ) emission scenarios in this chapter. Table 4.1
provides present and future atmospheric mixing ratios of CO 2 and CH 4 , from both
RCP 4.5 and RCP 2.6. Strict reductions in the anthropogenic emission of both GHGs
will be needed to achieve either of the RCP 4.5 or RCP 2.6 trajectories.
Much of the focus in this chapter is on emissions of CO 2 because this gas is the
primary driver of climate change. We first compare projections of emissions of CO 2
associated with world energy demand developed by the US Energy Information
Administration (EIA) to the emissions that will be needed to achieve the RCP 4.5 and
RCP 2.6 pathways. We then use satellite observations of light visible from space at
night, known as night lights, to illustrate the economic disparity between various
parts of the world. For reductions of GHG emissions to occur on a scale to reach RCP
4.5, the developed world must transition to a massive use of renewable energy, not
only to generate electricity, but also to supply heat and a considerable portion of
other energy needs. If the developing world is to electrify and industrialize, then this
will have to happen in a manner that relies heavily on the use of renewable energy,
rather than combustion of fossil fuels, to have a good chance of achieving the upper
limit, much less the target, of the Paris Climate Agreement. For the GHG emission
reductions of RCP 2.6 to be achieved, carbon capture and sequestration as well as the
massive transition to renewables will need to be implemented on a global scale.
We conclude by presenting an analysis of the transient climate response to cumu-
lative CO 2 emissions (TCRE) (Allen et al. 2009 ; Rogelj et al. 2016b; MacDougall
and Friedlingstein 2015 ), a policy relevant metric highlighted in the Summary for
Policy Makers of IPCC (2013). Estimates of TCRE from our EM-GC are compared
to values from the CMIP5 GCMs. Finally, we also provide an assessment of the
impact of future growth in CH 4 , independent of CO 2 , on the probability of achieving
the Paris Climate Agreement.

Table 4.1 Atmospheric CO 2 and CH 4 mixing ratios, in parts per million (ppm)

GHG Present day

2060 2100

RCP 4.5 RCP 2.6 RCP 4.5 RCP 2.6

CO 2 404 509 442 538 421

CH 4 1.84 1.80 1.37 1.58 1.25

4.1 Introduction