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2.3 Global Futures Scenarios
Global futures scenarios do not specifically or uniquely consider GHG emissions.
Instead, they are more general “stories” of possible future worlds.
They can complement the more quantitative emissions scenario assessments, because
they consider dimensions that elude quantification, such as governance and social
structures and institutions, but which are nonetheless important to the success
of mitigation policies. Addressing these issues reflects the different perspectives
presented in Section 1: cost-effectiveness and/or efficiency,
equity, and sustainability.
A survey of this literature has yielded a number of insights that are relevant
to GHG emissions scenarios and sustainable development. First, a wide range
of future conditions has been identified by futurists, ranging from variants
of sustainable development to collapse of social, economic, and environmental
systems. Since future values of the underlying socio-economic drivers of emissions
may vary widely, it is important that climate policies should be designed so
that they are resilient against widely different future conditions.
Second, the global futures scenarios that show falling GHG emissions tend to
show improved governance, increased equity and political participation, reduced
conflict, and improved environmental quality. They also tend to show increased
energy efficiency, shifts to non-fossil energy sources, and/or shifts to a post-industrial
(service-based) economy; population tends to stabilize at relatively low levels,
in many cases thanks to increased prosperity, expanded provision of family planning,
and improved rights and opportunities for women. A key implication is that sustainable
development policies can make a significant contribution to emission reduction.
Third, different combinations of driving forces are consistent with low emissions
scenarios, which agrees with the SRES findings. The implication of this seems
to be that it is important to consider the linkage between climate policy and
other policies and conditions associated with the choice of future paths in
a general sense.
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Figure TS.1: Qualitative directions of SRES scenarios for different
indicators.
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2.4 Special Report on Emissions Scenarios
Six new GHG emission reference scenario groups (not including specific climate
policy initiatives), organized into 4 scenario “families”, were developed
by the IPCC and published as the Special Report on Emissions Scenarios (SRES).
Scenario families A1 and A2 emphasize economic development but differ with respect
to the degree of economic and social convergence; B1 and B2 emphasize sustainable
development but also differ in terms of degree of convergence (see Box
TS.1). In all, six models were used to generate the 40 scenarios that comprise
the six scenario groups. Six of these scenarios, which should be considered
equally sound, were chosen to illustrate the whole set of scenarios. These six
scenarios include marker scenarios for each of the worlds as well as two scenarios,
A1FI and A1T, which illustrate alternative energy technology developments in
the A1 world (see Figure TS.1).
The SRES scenarios lead to the following findings:
- Alternative combinations of driving-force variables can lead to similar
levels and structure of energy use, land-use patterns, and emissions.
- Important possibilities for further bifurcations in future development trends
exist within each scenario family.
- Emissions profiles are dynamic across the range of SRES scenarios. They
portray trend reversals and indicate possible emissions cross-over among different
scenarios.
- Describing potential future developments involves inherent ambiguities and
uncertainties. One and only one possible development path (as alluded to,
for instance, in concepts such as “business-as-usual scenario”)
simply does not exist. The multi-model approach increases the value of the
SRES scenario set, since uncertainties in the choice of model input assumptions
can be more explicitly separated from the specific model behaviour and related
modelling uncertainties.
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Box TS.1. The Emissions Scenarios of the IPCC Special Report on
Emissions Scenarios (SRES)
A1. The A1 storyline and scenario family describe a future
world of very rapid economic growth, global population that peaks in
mid-century and declines thereafter, and the rapid introduction of new
and more efficient technologies. Major underlying themes are convergence
among regions, capacity building, and increased cultural and social
interactions, with a substantial reduction in regional differences in
per capita income. The A1 scenario family develops into three groups
that describe alternative directions of technological change in the
energy system. The three A1 groups are distinguished by their technological
emphasis: fossil intensive (A1FI), non-fossil energy sources (A1T),
or a balance across all sources (A1B) (where balanced is defined as
not relying too heavily on one particular energy source, on the assumption
that similar improvement rates apply to all energy supply and end-use
technologies).
A2. The A2 storyline and scenario family describe a very
heterogeneous world. The underlying theme is self-reliance and preservation
of local identities. Fertility patterns across regions converge very
slowly, which results in a continuously increasing population. Economic
development is primarily regionally oriented and per capita economic
growth and technological change more fragmented and slower than in other
storylines.
B1. The B1 storyline and scenario family describe a convergent
world with the same global population, which peaks in mid-century and
declines thereafter, as in the A1 storyline, but with rapid change in
economic structures towards a service and information economy, with
reductions in material intensity and the introduction of clean and resource-efficient
technologies. The emphasis is on global solutions to economic, social,
and environmental sustainability, including improved equity, but without
additional climate initiatives.
B2. The B2 storyline and scenario family describe a world
in which the emphasis is on local solutions to economic, social, and
environmental sustainability. It is a world with continuously increasing
global population, at a rate lower than in A2, intermediate levels of
economic development, and less rapid and more diverse technological
change than in the B1 and A1 storylines. While the scenario is also
oriented towards environmental protection and social equity, it focuses
on local and regional levels.
An illustrative scenario was chosen for each of the six
scenario groups A1B, A1FI, A1T, A2, B1, and B2. All should be considered
equally sound.
The SRES scenarios do not include additional climate initiatives,
which means that no scenarios are included that explicitly assume implementation
of the United Nations Framework Convention on Climate Change or the
emissions targets of the Kyoto Protocol.
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