3.2.4. Use of Socioeconomic Scenarios
This section presents a set of case studies that illustrates a range of specific
approaches to the construction of socioeconomic scenarios that are relevant
to climate impact assessment.
22.214.171.124. IPCC Special Report on Emissions Scenarios
The IPCC's Special Report on Emissions Scenarios (SRES) (Nakicenovic
et al., 2000) was prepared to improve on the earlier set of six IS92
scenarios developed in 1992 (Leggett et al., 1992). The SRES describes
40 scenarios in allbased on an extensive literature assessment, six alternative
modeling approaches, and an "open process" that solicited worldwide
participation and feedback. The scenarios (which are described in more detail
in Section 3.8) cover the main demographic, economic,
technological, and land-use driving forces of future emissions. They include
emissions of all relevant GHGs plus sulfur dioxide (SO2), carbon
monoxide (CO), nitrogen oxides (NOx), and nonmethane volatile organic
hydrocarbons (VOCs). The IPCC specified that the scenarios should not include
future policies that explicitly address climate change. However, they necessarily
encompass other policies that may indirectly influence GHG sources and sinks.
The scenarios suggest that assumptions about technology, rather than population
and economic development, may be the most important driving force of future
The SRES emissions scenarios serve several purposes. First, they provide baselines
of socioeconomic, technological, and land-use change, in combination with emissions
trajectories, for the assessment of mitigation policies and measures (see TAR
WGIII Chapter 2). Second, they can be used to drive
the assessment of climate change (see TAR WGIII and Section
3.8). Third, they provide a global socioeconomic framework for regional-scale
assessment of impacts and adaptation [e.g., see the United Kingdom Climate Impacts
Programme (UKCIP) and European ACACIA examples, below].
126.96.36.199. UNEP Pakistan Country Study
The Pakistan Environment Ministry has produced a suite of three socioeconomic
scenarios to inform national climate impact and adaptation planning (Government
of Pakistan, 1998). The scenarios focus on two reference years2020 and
2050and include a combination of quantitative and qualitative indicators.
Quantitative scenarios are presented for population, economic growth, agricultural
production, energy demand, and industrial output. Variations in future rates
of literacy, health care, import tariffs, forest cover, and infrastructure are
expressed in qualitative terms. The 2020 scenario is the more detailed of the
two; it is a composite of existing national projections and scenarios produced
for "nonclimate" policymaking. The 2020-2050 scenarios were developed
for the sole purpose of informing climate impact assessments and are much less
detailed (Tol, 1998).
188.8.131.52. UKCIP "Nonclimate Scenarios" for Climate
A set of "nonclimate scenarios" has been developed to provide a common
framework for assessing climate impacts and adaptation under the stakeholder-led
UKCIP (Berkhout et al., 1999). The scenarios were based on a broader
"Environmental Futures" exercise (UK National Foresight Programme,
1999)which, in turn, had drawn on emerging SRES work.
Four scenarios for the 2020s and 2050s were defined by two factors affecting
the capacity and willingness of society to adapt to climate change: the extent
to which social values reflect environmental concern and the effectiveness of
governance institutions. Development of the scenarios involved extensive consultations
with stakeholders (Lorenzoni et al., 2000). As a result, detailed scenario
characterization was confined to the 2020s. For each scenario, key national
indicators were developed. These indicators included population and GDP, as
well as more specific variables relating to land-use change, patterns of agricultural
activity, water demand, and investment in coastal defense. In addition, climate
vulnerability was assessed qualitatively in several "impact domains,"
including agriculture, water, biodiversity, coastal zone management, and infrastructure
and the built environment.
The framework scenarios were found to be a useful starting point for subsequent
studies. However, the scenarios needed to be articulated in more detail to be
useful at the regional or sectoral level. More quantification generally was
required. This exercise underlined the need for scenarios to be tailored for
end users, while maintaining broad consistency about key indicators such as
population and GDP.