Spatial Approaches for Assessing Vulnerability and Consequences in Climate Change Assessments

Understanding the socio-economic implications of climate change at the regional level requires integrating information regarding climatic hazards with information regarding environmental, social, and economic systems that are exposed to those hazards. Achieving such spatial integration is non-trivial due to issues of data availability, compatibility and scale. Here, we examine two different approaches, one 'vulnerability-based' and one 'impact-based', from ongoing regional integrated assessment projects in Australia. [GRAPHICS] A 'vulnerability-based' approach has been employed in the Sydney Coastal Councils Group region, New South Wales to map the potential for future harm across the region to five climate change impacts: extreme heat and health effects, sea-level rise and coastal management, extreme rainfall and urban stormwater management, bushfire and ecosystems and natural resources. Multiple indicators were integrated to generate spatial maps of the three components of vulnerability: exposure, sensitivity and adaptive capacity (Figure 1). These were subsequently combined to generate a map of net vulnerability. Indicators included current regional climate gradients, projections of future climate change, topography, land use and cover, demographic information as well as indicators of council resources and performance. While the vulnerability approach captures a broad range of potential factors that may contribute to harm, it does not actually predict consequences. As such, it is flexible to data inputs and uncertainties and allows the incorporation of diverse sources of information, even in the absence of knowledge regarding how those data sources interact. Nevertheless, the interpretation of vulnerability in the context of decision-making can be difficult. In contrast, an 'impact-based' approach is being utilised in the Western Port region of Victoria, which utilises quantitative spatial projections of future climate change and climate hazards in the quantification of affected land areas, infrastructure and populations. This predictive approach gives an indication of the scale of consequences and identifies specific assets that may be affected. These qualities allow easier interpretation and incorporation into existing risk management frameworks. However, predictions of consequences are often dependent upon access to high-quality data, and results are associated with significant uncertainties. Furthermore, it is difficult to incorporate other factors (such as the capacity for adaptation) that may influence impacts. Both vulnerability and impact-based approaches can provide useful information to stakeholders. Deciding which is appropriate for informing stakeholders is a function of the assessment and the questions for which stakeholders seek answers as well as potential temporal financial or technical constraints on the assessment process.