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3.2.3. Constructing Socioeconomic Scenarios
Socioeconomic scenarios can be constructed in the same variety of ways and
for the same variety of purposes as global change scenarios in general. In practice,
a variety of approaches may be combined in a single exercise. The UNEP country
studies program has developed detailed guidance on construction and use of socioeconomic
scenarios (Tol, 1998). This guidance emphasizes the importance of avoiding simple
extrapolation-especially for developing countries, which may be undergoing demographic
or economic transition; the role of formal modeling in filling in, but not defining,
scenarios; and the role of expert judgment in blending disparate elements into
coherent and plausible scenarios.
Most socioeconomic scenarios cover several different topics or domains, such
as population or economic activity. Table 3-1 shows
the range of issues covered in recent scenario or scenario-based exercises.
3.2.3.1. Basic Drivers
Population and economic activity are characterized in quantitative terms in
most scenario exercises. The degree of disaggregation according to world region,
country, or sector varies from one study to another. Coverage of other socioeconomic
domains also can vary markedly among different activities.
3.2.3.2. Underlying Socioeconomic Drivers
Some scenarios incorporate explicit assumptions about underlying socioeconomic
drivers of change such as social values and governance institutions. These scenarios
usually are generated through synthetic or expert judgment-led approaches, expressed
in qualitative terms. Social values can affect the willingness of societies
to preserve ecosystems or protect biodiversity. Institutional and governance
factors affect the capacity of a society to organize and direct the resources
needed to reduce climate vulnerability (Adger, 1999). Qualitative factors such
as institutional effectiveness and social values are key determinants of the
effectiveness of coping strategies for adapting to climate change (see Chapter
18). They determine adaptive capacity and hence the vulnerability of socioeconomic
systems. They are critical in any assessment of the implications of climate
change for development, equity, and sustainability (Munasinghe, 2000).
3.2.3.3. Technological Change
Technology critically affects the capacity to adapt to climate change; it confers
opportunities and risks. For example, genetic modification of crops and other
developments in agricultural technology could enhance that sector's ability
to adapt to different climatic conditions. However, excessive reliance on one
particular strain of plant might increase vulnerability.
Technological change must be characterized in quantitative and qualitative
terms. It may be very difficult to identify specific features of a technology
that could affect vulnerability to climate change. Expert judgments are needed
about the direction in which change takes place, public acceptability of different
options, and the rate of adoption in the marketplace. Quantitative assumptions
will be needed about the rate of improvement of a technology, including its
cost, overall efficiency in using resources to meet the need for a given service,
and possible impacts at various scales.
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