International assessments of the vulnerability.pdf - Climate ...

International assessments of the vulnerability of the coastal zone to climate change, including an Australian perspective
levels of flooding, accelerated erosion, loss of wetlands and mangroves, and seawater
intrusion. These issues were explored in detail in Chapter 6 on coastal zones and
marine ecosystems, which recognised that low-lying islands and extensive coastal
plains associated with estuaries and deltas appear particularly at risk. Chapter 12,
which describes Australia (and New Zealand), recognises the vulnerability of coral
reefs, such as the Great Barrier Reef with the probability of more frequent coral
bleaching, and vulnerability of low-lying wetlands that are extensive along the north
Australian coastline. The report also includes a section (12.6.4) considering the
implications of the rapid economic and population expansion along Australia’s coasts
leading to greater community risk and insurance exposure to present and future
hazards (Pittock, 2003).
Since the TAR in 2001, there has been an increasing body of evidence to suggest that
global warming is already having an effect on reefs, with more frequent tropical seasurface
temperatures exceeding the tolerance of corals, leading to more widespread
coral bleaching. It seems likely that the Fourth Assessment report, to be produced by
IPCC in 2007, will further focus on these issues, emphasising the exposure of reefs in
north-eastern Australia and wetlands in northern Australia. Low-lying coasts around
Australia might be expected to experience increased levels of inundation, accelerated
coastal erosion, and saline intrusion into coastal waterways and water tables.
Evidence points to a severe impact potential, but presently knowledge of the
vulnerability of coastal areas to sea-level rise and wider climate change remains
incomplete. There is uncertainty about the rates of change and it is difficult to
separate extreme events exacerbated by climate change from those that represent part
of the current natural variability of climate.
1.2 Definition of terms
Vulnerability is commonly defined as ‘the degree to which a system is susceptible to,
or unable to cope with, adverse effects of climate change’ (IPCC, 2001a). Following
the Allan Consulting Group report, vulnerability can be considered a function of
‘exposure’, the background climate conditions against which a system operates and
any changes in those conditions, and ‘sensitivity’, the degree to which the system is
affected by climate related stimuli; these together constitute the potential impact. This
potential impact is further influenced by adaptive capacity, the ability of a system to
adjust to climate change so as to moderate potential damage or to cope with its
consequences (Allan Consulting Group, 2005).
In discussions of vulnerability of coasts it has generally been found useful to adopt the
framework summarised in Figure 1, distinguishing between natural system
vulnerability and socio-economic vulnerability to climate change, but emphasising
their interrelatedness and interdependence (Klein and Nicholls, 1999). Assessment of
vulnerability needs to start with an understanding of the natural system and its
biophysical response to climate change (in particular sea-level rise); these comprise
its susceptibility (exposure, or potential of the system to be affected by hazards), and
its responsiveness or natural capacity to cope, measured by resistance or resilience
(sensitivity). Coastal landforms and ecosystems may show resistance, which includes
mechanical strength of materials, structural, ecological, and morphological resistance,
and they may show natural resilience, the ability of the system to bounce back, or
return to some quasi-stable state. Although these terms are most familiar in relation to
Australian Greenhouse Office, Department of the Environment and Heritage, 2006
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