3.2.4.4. ACACIA Scenarios for Europe
ACACIA (A Concerted Action Towards A Comprehensive Climate Impacts and Adaptations
Assessment for the European Union) assessed climate impacts and potential adaptation
in Europe to the 2080s (Parry, 2000). ACACIA elaborated four scenarios on the
basis of a combination of the UKCIP and SRES approaches (Jordan et al.,
2000; see also Chapter 13). This analysis concluded that
certain systems will thrive under some scenarios and will be inherently more
vulnerable in others, independent of climate change. Adaptive strategies are
likely to differ across the four scenarios. In addition, the manner in which
society values different parts of the human and physical environment is markedly
different under the different scenarios, with clear implications for adaptation
policies.
3.2.4.5. U.S. National Assessment
The approach to socioeconomic scenarios adopted by the U.S. National Assessment
of Climate Impacts was determined by the nature of the assessment process, with
a national synthesis linking separate analyses in nine U.S. regions and five
sectors (National Assessment Synthesis Team, 1998). Recognizing that the sensitivity
of particular regions or sectors may depend on highly specific socioeconomic
characteristics, the assessment adopted a two-part approach to scenario development.
First, to allow national aggregation, high, medium, and low scenarios were specified
for variables such as population and GDP to be used by all subnational analyses
(NPA Data Services, 1999). Second, teams were asked to identify a small number
of additional socioeconomic variables that would have the strongest and most
direct influence on their particular region or sector. They developed and documented
their own assumptions for these variables, following a consistent template developed
by the National Assessment Synthesis Team (NAST) (Parson, 1999). High and low
values then could be assumed for each key impact variable, without having to
specify what combination of demographic, market, ecosystem, and technological
factors caused it to take a particular value. Teams were advised to construct
a small set of high- and low-impact scenarios on the basis of different combinations
of assumptions about key impact variables. Instead of an idealized approach
to scenario development, which would have attempted to specify all factors consistently
across different sectors and regions, the more pragmatic and pluralistic approach
adopted in the U.S. National Assessment allowed regional and sectoral specificities
to be reflected.
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