Sustainability and policy - Climate Change: Biological and Human Aspects - page 508

will follow the peak, policies to both facilitate production and curb oil consumption
(through improved efficiency and the use of other sources of energy) would need to
be instigated two decades in advance; that is, now.
On a purely economic basis real-term price increases in natural gas and oil will
again make liquid- and gas-fuel conversion from coal more attractive. However, there
will be economic repercussions in the 22nd century as economic reserves of coal, if
heavily exploited, will themselves become depleted. Consequently, in the very long
term (from a human perspective), all fossil- (including coal-derived) fuel costs will be
subject to a real-term marked rise. On a climate basis, without some form of carbon
capture (which at this time is not easy to envisage), extensive use of coal as predicted
over such a scale of the coming century will mean that climate change is likely to
follow the higher IPCC forecasts into the 22nd century (which has not to date been
the subject of principal IPCC focus). What it also means is that by then the human
perturbation of the carbon cycle will be of a comparable order to that of the early
Eocene carbon isotope excursion (see sections 3.3.9 and 6.6.4), and hence increase
the likelihood of setting in train some similar climatic event.
8.4.3 Nuclearfutures
In part because of the above economics, and in part because it is a low- (although not
entirely zero-) fossil carbon resource, nuclear fission is likely to become increasingly
more attractive in the future. Although there are, and will likely continue to be,
concerns over radioactive waste and potential nuclear proliferation, it is difficult not
to see many countries adopting nuclear power, or increasing their existing nuclear-
generating capability by the middle of the century. The scale of fission development
(and its nature, such as developing or not fast-breeder reactors) will influence the rate
at which high-grade uranium ore reserves are depleted. At some stage (somewhere
from the middle of the century, but it is unclear when), as high-grade uranium
ore deposits are depleted, the cost of fission will rise. Increased fission costs would
be bearable if cheaper fossil fuel ran out and/or if fossil fuel combined with carbon
capture was at least as expensive. This would enable lower-grade uranium ore be
extracted and processed.
Ore extraction and processing currently has a carbon cost in that oil is used to
transport the ore and energy is used to process it and to isotopically enrich the fuel.
This processing and enrichment energy in our high-fossil-using present day currently
necessitates some fossil carbon consumption (although nuclear power still offsets
more carbon than it consumes; see Chapter 7). However, in a potentially low-fossil
future (with high use of nuclear or renewable energy) this nuclear-fuel-manufacturing
energy could conceivably come from renewable energy and nuclear power itself: such
are the complexities that make energy futures difficult to predict. Currently part of this
carbon cost is offset by nuclear electricity generation displacing electricity generation
that would otherwise have been undertaken by fossil fuels. However, if lower-grade
uranium ore is mined, then more oil is used in its transportation and more energy
for processing and enrichment. Of course, if we were by then in a largely renewable-
and alternative-energy future then conceivably fossil carbon would not be required to
contribute to a nuclear infrastructure.