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58 Managing Global Warming

As a somewhat arbitrary lower limit, I have assumed that whatever the GGR target
may be, it is implausible that it could be achieved in fewer years than the target in
Gt(C)/yr multiplied by 4. Thus, to reach a GGR target of 10Gt(C)/yr would take at
least 40 years. The primary constraints are political, scientific, and engineering. With-
out the political will to provide the funding for research and development, the science
will not progress fast enough. Even once the science points the way, the scale of the
infrastructure required to deliver any form of GGR at climate relevant quantities will
become constrained by the global capacity to build at the necessary pace.
The final parameter whose plausibility range must be considered is the requirement
for ZEE. This is discussed in Section 2.7 where I conclude that rather than restricting
the range of plausible future values for ZEE, the ZEE requirement can be seen as an
emergent global policy objective.
The upper and lower plausibility bounds of the eleven independent variables are set
out in Table 2.3.

Table 2.3 Summary of plausibility ranges for the eleven independent
variables
Best plausible Worst plausible
Parameter value value
Emissions (FF)
Peak emissions year 2017 2040
Residual FF and cement emissions (RE) (Gt 0 10
(C)/yr)
Years to reach residual emissions (PE¼peak 40 (PE RE)/PE 120 (PE RE)/PE
emissions in Gt(C) dynamically determined)

Energy consumption (TFC)
Energy consumption reductions start (ERSY) 2017 2100
Percentage reduction of energy consumption 20 0
(PREC) (%)
Years to deliver incremental reduction of PREC 50 2100 ERSY
energy consumption

Carbon intensity (CIR)
Carbon intensity reductions start (CRSY) 2017 2100
Percentage CIR (PCIR) (%) 25 0
Years to deliver incremental CIR PCIR 50 2100 CRSY

GGR
GGR start year (SSY) 2025 2050
Years to reach maximum GGR (MSY) MSA/4 MSA/4
(MSA¼maximum GGR amount
(Gt(C)/yr) dynamically determined)