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17.3.3. Vulnerability
Despite their heterogeneity, small island states share some common characteristics
that help to define their high vulnerability and low adaptation potential to
climate change effects (Nurse et al., 1998; see also Section
17.1.2). Vulnerability assessment typically seeks to achieve three main
goals: to identify the degree of future risks induced by climate change and
sea-level rise; to identify the key vulnerable sectors and areas within a country;
and to provide a sound basis for designing adaptation strategies and their implementation.
The IPCC Common Methodology was the first method to be widely applied to assess
the vulnerability of countries to sea-level rise (IPCC, 1992). However, the
methodology lacks the flexibility to consider factors of critical significance
for small islands (e.g., so-called nonmarket goods and services) and requires
certain quantitative data that often are not easily available in many small
island states. An index-based method was developed for use in the south Pacific
(Yamada et al., 1995, based on Kay and Hay, 1993). In addition, alternative
assessment methodologies were developed in conjunction with the various country
study programs (e.g., Leatherman, 1996; Klein and Nicholls, 1998). What is significant,
however, is that all available assessments confirm the high vulnerability of
small island states to climate change, independent of the methodology applied.
As already noted, global assessments come to the same conclusions (Nicholls
et al., 1999). This is therefore a robust finding, which must be of considerable
concern to these countries.
Climate change is expected to be one factor among many that
affect ecological systems and economic development. Other factors that interact
with climate change include overexploitation of resources, pollution, increasing
nutrient fluxes, decreasing freshwater availability, sediment starvation,
and urbanization (Goldberg, 1994; Viles and Spencer, 1995). Particularly relevant
for small island states are rapid population growth, intra- and inter-island
migration, rapid changes in social structure, and effects of economic globalization.
These nonclimate stresses can decrease the resilience of natural and human
systems, increasing their vulnerability to climate variability and anticipated
climate change (Nicholls and Branson, 1998; Klein and Nicholls, 1999).
Most vulnerability indices developed to date have focused on economic and social
systems, although studies by Ehrlich and Ehrlich (1991) and Atkins et al.
(1998) focus on environmental vulnerability. The economic vulnerability indices
include those developed by Briguglio (1995, 1997), the Commonwealth Secretariat
(Wells, 1996, 1997; Atkins et al., 1998), Pantin (1997), and the Caribbean
Development Bank (Crowards, 1999). Another index, the Environmental Vulnerability
Index, has been developed recently for small island states, particularly countries
for which data availability is limited. It incorporates climate, nonclimate,
and human stresses on the environment and seeks to reflect relative vulnerability
as a function of these combined factors (Kaly et al., 1999). All vulnerability
indices consistently identify small states—sometimes more specifically
small island states—as being more economically vulnerable than larger states.
Most existing studies have fulfilled the first two of the three aforementioned
goals of vulnerability assessment, although information on socioeconomic impacts
of climate change often is limited. The third goal—to provide a basis to
guide possible adaptation—usually is met only in general terms. Effective
planning and design of adaptation strategies requires more detailed information
on crucial vulnerable sectors and areas. Such information may be partly derived
from analysis at an integrated level (see Box 17-2)—as
suggested, for instance, by Klein and Nicholls (1999).
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Box 17-2. Tools for Vulnerability Assessment and
Adaptation Policy Development
The numerous and well-developed interactions between the natural and human
systems of island countries underscore the relevance of integrated assessment
as a meaningful analytical tool for designing adaptation strategies.
One such tool that has proven particularly beneficial is VANDACLIM,
an integrated assessment model developed by the International Global
Change Institute (University of Waikato, New Zealand), in collaboration
with the South Pacific Regional Environment Programme (SPREP) and United
Nations Institute for Training and Research (UNITAR) (Warrick et
al., 1999). Enhanced and country-specific versions of VANDACLIM
currently are being developed.
Development of VANDACLIM involved linking a regional scenario generator
with selected impact models for four key sectors: agriculture, coastal
zones, human health, and water resources. The user has considerable
flexibility in generating scenarios; the user can choose among a large
range of projections from GHG emission scenarios; the low, mid, or high
cases from each projection (which encompasses the range of uncertainty
in model parameter values); several GCM patterns; and the year of interest
(in 5-year increments from 1990 to 2100).
VANDACLIM integrates a variant of the "Bruun rule" with a
simple inundation model that is suitable for flat, low-lying deltaic
coastal plains. Health impacts projections are derived from a biophysical
index that estimates potential incidence of malaria and a simple threshold
index for estimating change in the risk of cholera outbreaks related
to extreme flooding events. For water resources, three models are included:
an atmospheric water balance model for assessing the overall water resource
situation for the country; a water balance-river discharge model for
estimating monthly mean discharge for estimating wet and dry season
river flow; and a discharge-flood area model for defining the areal
extent of flooding. For agriculture, various crop models and indices
are integrated, including degree-day models, rainfall (soil moisture),
a land suitability index, and temperature for a variety of tropical
crops.
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