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Understanding and Assessing Vulnerability

Before the questions posed above can be answered, the extent and severity of climate change on coastal natural systems and habitats must be defined and analysed. Invariably this should take the form of a vulnerability assessment.

IPCC defines vulnerability as ‘the degree to which a system is susceptible to, or unable to cope with, adverse effects of climate change. Vulnerability is a function of the character, magnitude, and rate of climate variation to which a system is exposed, its sensitivity, and its adaptive capacity’ (IPCC 2001 quoted in Australian Government 2009; Brooks 2003). In summary, vulnerability is a function of exposure, sensitivity and adaptive capacity as shown in Fig. 26.1.

Vulnerability of coastal environments to future climate change is broad given that there are a number of climate factors that potentially influence coastal ecosystems. Nicholls et al. (2008) summarised climate factors and there potential influence on coastal environments. Table 26.1 presents an adaptation of Nicholls et al. (2008).

Fig. 26.1 Components of vulnerability (adapted from Australian Government 2009)

Table 26.1 Climate change parameters and potential vulnerability of coastal ecosystems (adapted

from Nicholls et al. 2008)

Climate change parameter

Environmental coastal ecosystem response to driver

Sea level rise

Shoreline recession; saline inundation of low-lying lands; saltwater intrusion into freshwater wetlands and groundwater systems; rising groundwater levels; vegetation change in response to hydrology and salinity changes

Increased storminess (intensity) and associated storm tide inundation

Increased extreme ocean water levels; increased storm erosion or shorelines; increased frequency of inundation of low-lying lands

Changes to rainfall patterns

Changes to flood risk in low-lying lands; altered water quality and salinity; changes to alluvial sediment supply; changes to nutrient supply from catchment

Increased temperature

Increase in evaporation, decrease in groundwater levels; decrease in surface water ponding; vegetation change

The assessment of vulnerability can range from a rapid assessment of a large area or network (say across the protected area or World Heritage estate of a national government) to specific habitat types (for instance a climate change assessment of future impacts to coral reefs); to a particular site such as an small island or beach. One thing to consider here is that while assessment of vulnerability can be done at various spatial scales, adaptation management to address vulnerability will be most effective at a local scale where:

  • • the impacts on values and systems can be more perceptible;
  • • the trajectory of impact is clearer, can be locally monitored, and can be readily communicated to local stakeholders; and
  • • the development, implementation and evaluation of the effectiveness of management actions can be more readily observed and measured.

Ultimately the vulnerability assessment should assist the coastal manager to understand how various climate change issues and trends may affect the resource values including key parameters such as the extent and condition of habitat components (e.g. systems and species) and the natural and anthropogenic ecosystem services provided by the habitat. In this context, the current condition or exposure of the receiving environment to impact can be critical to understand as a first step, particularly when considering the resilience of the system to change.

Some recent examples of climate change vulnerability studies focused on coastal and marine assets in Australia include the Great Barrier Reef Outlook Reports (2011, 2014) and associated Strategic Assessments; Implications of Climate Change for Australia’s World Heritage Properties: A Preliminary Assessment (Commonwealth of Australia 2009); Climate Change Risks to Australia’s Coast: A First Pass National Assessment (Australian Government 2009).

In the Pacific, reports prepared under the SPREP PACC (Pacific Adaptation to Climate Change Programme) such as ‘Ecosystem-based adaptation and climate change vulnerability for Choiseul Province, Solomon Islands: synthesis report’ (Iacovino et al. 2013) and other local studies such as the ‘Comparative Analysis of ecosystem-based adaptation and engineering options for Lami Town, Fiji’ (UNEP 2012) are relevant. Also, the recently released ‘Integrated Vulnerability Assessment Framework for Atoll Islands—A collaborative Approach’ (SPC 2016) is informative in providing an overarching approach to undertaking vulnerability assessments for coastal environments.

Using these studies and guidelines as representation of best practice documents, we have formulated an essential seven-step methodology for assessing vulnerability of coastal and marine natural assets, as presented in Table 26.2.

Table 26.2 Methodology for assessing vulnerability of coastal and marine environments

Step 1: Establish the environmental, social and economic values/assets of the coastal system that could be affected by climate change

Step 2: Consider the different aspects of climate change (e.g. sea level rise, changes to rainfall patterns, storminess, etc.) that may affect the values of the asset both in isolation and interactively

Step 3: Determine and map what habitats and species (upon which the values depend) are at particular risk from future climate change aspects

Step 4: Determine the current extent and condition of these habitats and species and how they may change/shift as a result of climate change (e.g. will they succeed landward in response to sea level rise?)

Step 5: Predict responses to climate change using models and other numerical tools to better define spatially and temporally how the habitats and species will respond

Step 6: Examine at broader landscape and bioregional scales, the implications of losing vulnerable species and habitats—are there refugia habitats with similar values that are not going to be affected by climate change impacts

Step 7: Identify key knowledge gaps and recommending monitoring to fill these gaps

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