2.4.4 Global Futures Scenarios, Greenhouse Gas Emissions, and Sustainable
Figure 2.9: CO2 Emissions in Global Futures Scenarios
(narrative scenarios). Acronyms: OCF, the Our Common Future
scenario from Duchin et al., 1994; GS, the Global Shift; ER,
the European Renaissance; GC, the Global Crisis;
and BG the Balanced Growth scenarios from the Central Planning
Bureau of the Netherlands (CPB, 1992); A1, A2, A3, B, C1 and C2, scenarios
from Nakicenovic et al., 1998; CW-R, Conventional Worlds
Reference; and CW-PR, Conventional Worlds Policy Reform
from Gallopin et al., 1997 and Raskin et al., 1998. Note that this figure
shows emission projections from a subset of the Global Futures Scenarios
which discuss emissions, and a slightly higher proportion of scenarios
in this larger group foresee declining emissions (13 of 35 scenarios,
compared to 4 of 14 scenarios shown in the figure).
Of the 124 global futures scenarios in the database, 35 provide some kind of
projection of future GHG (usually CO2) emissions. These projections
range from narrative descriptions (e.g., emissions continue to rise)
to numerical estimates. Figure 2.9 shows global carbon
dioxide emissions projections from the scenarios that provide numerical estimates.
Most (22) of these scenarios project increased emissions, but several (13)
foresee declining emissions. All but one of the latter scenarios are Sustainable
Development scenarios in which there is a concerted policy effort towards emission
reduction, innovation in energy development towards improved efficiency and
conservation, and/or alternatives to fossil fuels. The exception is a High-Tech
Optimist scenario in which energy efficiency technologies and a shift to low-
and non-fossil fuels bring about declining emissions.
The Sustainable Development scenarios that project declining emissions are
in general characterized by increased co-operation and political participation;
many assume that there is strong international agreement on the environment
and development in general and climate change in particular. There is improved
environmental quality and equity and, in several scenarios, increased material
affluence globally (although some scenarios indicate a decline in consumerism).
Population continues to grow but at slower rates and stabilizes at relatively
low levels. In most scenarios significant developments of energy efficiency,
energy conservation, and alternative energy technologies are key to emission
reduction; a number of scenarios assume a tax on fossil fuels.
Table 2.4 summarizes the apparent relationships between
emissions and scenario dimensions. It is important to note that there is considerable
variety among the scenarios; Table 2.4 therefore shows
relationships that were in the majority, but not necessarily all, of the scenarios.
It should also be noted that the relationships shown in Table
2.4 do not by themselves prove causation; they simply reflect what the majority
of scenarios with rising and falling GHG emissions, respectively, indicate for
each scenario dimension.
What is clear from Table 2.4 is that there are no strong
patterns in the relationship between economic activity and GHG emissions. Growth
in economic activity is compatible, across this set of scenarios, with both increasing
and decreasing GHG emissions. In the latter case, mediating factors include increased
energy efficiency, shifts to non-fossil energy sources, and/or shifts to a post-industrial
(service-based) economy. Similarly, population growth is present in scenarios
with rising emissions as well as scenarios with falling emissions, although in
the latter group of scenarios, population tends to stabilize at relatively low
levels, in many cases owing to increased prosperity, expanded provision of family
planning, and improved rights and opportunities for women.
|Table 2.4: Factors associated with changing
GHG emissions in global futures scenarios
|Growing, post-industrial economy with globalization, (mostly)
low government intervention, and generally high level of competition
|Some scenarios show rising GDP, others show economic activity limited
to ecologically sustainable levels; generally high level of government intervention
|Growing population with high level of migration
|Growing population that stabilizes at relatively low level; low level
|No clear pattern in governance
|Improvements in citizen participation in governance, community vitality,
and responsiveness of institutions
|Generally declining income equality within nations and no
clear pattern in social equity or international income equality
|Increasing social equity and income equality within and among nations
|High level of conflict and security activity (mostly), deteriorating
conflict resolution capability
|Low level of conflict and security activity, improved conflict resolution
|High level of technology, innovation, and technological diffusion
|High level of technology, innovation, and technological diffusion
|Declining renewable resource and water availability; no clear
pattern for non-renewable resource and food availability
|Increasing availability of renewable resources, food and water; no clear
pattern for non-renewable resources
|Declining environmental quality
|Improving environmental quality
The major visible difference has to do with environmental impacts. As might
be expected, pollution and the risk of ecological collapse are generally high
in scenarios which show rising GHG emissions, and low in scenarios which show
falling GHG emissions. Water availability and biodiversity decline in the scenarios
with rising GHG emissions, and rise or stay the same in the scenarios with falling
On a different front, in the scenarios with rising GHG emissions, conflict
and security activity are generally high, while government intervention in the
economy and income equality (within nations) are generally low. The reverse
is true in the scenarios with falling GHG emissions, which also show improving
equity between North and South. This would be expected from the fact that all
but one of these scenarios are Sustainable Development scenarios.
Chapter 3 of the SRES discusses the relationships between GHG emissions and
a number of driving forces, including population, economic and social development
(including equity), and technology. What is clear from that discussion, which
is consistent with the evidence summarized in Table 2.4,
is that the impacts on GHG emissions of changes in these underlying driving
forces are complex.
These complex relationships suggest that the choice of future world
is more fundamental than the choice of a few driving forces in determining GHG
emissions. The wide range of emissions in the various SRES baseline scenarios
also demonstrates this point. Choices about DES are crucial, not just for the
underlying conditions which give rise to emissions, but also for the nature
and severity of climate change impacts, and the success of particular mitigation
and adaptation policies. This finding is consistent with the discussion in Chapter
1, which suggests the central importance of DES issues in any consideration
of climate change.
It is important therefore that emission scenarios consider qualitative aspects
that are potentially important for future GHG emissions and mitigation policies.
One way to do this is to link these scenarios with the broader global futures
scenarios. However, this will be difficult because there are few areas of overlap,
as a result of the very different natures of the two kinds of scenarios. Perhaps
a more fruitful way of incorporating qualitative dimensions into quantitative
scenarios, already pursued by the Global Scenarios Group and others, as well
as in the SRES, is to develop quantitative estimates of key variables based
on qualitative descriptions of future worlds.
A survey of the global futures literature has yielded a number of insights
that are relevant to GHG emission 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 GHG emission scenarios
in particular, and climate change analysis in general, not limit themselves
to a narrow range of possible futures, but consider the implications for mitigation
of quite different sets of future conditions. In turn, climate policies should
be designed so that they are resilient against widely different future conditions.
Second, the global futures scenarios describe a wide range of worlds, from
pessimistic to optimistic, that are consistent with rising GHG emissions and
a smaller range of (generally optimistic) worlds that are consistent with falling
emissions. Scenarios that show falling emissions tend to show improved governance,
increased equity and political participation, reduced conflict, conditions supportive
of lower birth rates, and improved environmental quality. Scenarios with rising
emissions generally show reduced environmental quality and equity within nations
and increased conflict, and are more mixed with respect to governance and international
equity. Both types of scenarios generally indicate continued technological development.
The Sustainable Development scenarios suggest that sustainable development approaches
are feasible, and can lead to futures characterized by relatively low emissions.
A key implication is that sustainable development policies, taken generally,
can make a significant contribution to emission reduction.
Third, scenarios do not all show a positive relationship between emissions
and economic and population growth, as is commonly assumed (see also the discussion
of the Kaya identity in Section 18.104.22.168 of this chapter).
This is largely because, in the scenarios with declining emissions and rising
population and economic activity, policy, lifestyle choices, and technological
development act to reduce emissions through efficiency improvements, energy
conservation, shifts to alternative fuels, and shifts to post-industrial economic
structures. This suggests that different combinations of driving forces are
consistent with low emission scenarios, which agrees with the SRES findings.
The implication of this would seem 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. In other words, low emission
futures are associated with a whole set of policies and actions that go beyond
the development of climate policy itself.
In general, the global futures scenarios provide more comprehensive coverage
of the issues relevant to sustainable development than the general mitigation
scenarios described in section 2.3. They therefore
represent an important complement to the quantitative emission scenarios. However,
there are significant difficulties involved in trying to connect the mainly
narrative-based scenarios discussed in this section with the more quantitatively
oriented scenarios discussed earlier. In this connection, the work of the Global
Scenarios Group, the SRES, and others in linking narrative scenarios addressing
social, environmental, and economic elements of sustainable development with
model quantifications appears to point the way to the type of work
needed to better assess the implications of GHG mitigation for sustainable development
and vice versa. Section 2.5 below discusses the SRES
scenarios and process, as well as mitigation scenarios that were developed on
the basis of the SRES baseline scenarios.