Vera N. Agostini

Assessing vulnerability: an integrated approach for mapping adaptive capacity, sensitivity, and exposure

Making decisions and efficiently allocating resources to reduce the vulnerability of coastal communities requires, among other things, an understanding of the factors that make a society vulnerable to climate and coastal hazards. One way of doing this is through the analysis of spatial data. We demonstrate how to apply GIS methods to spatially represent socioeconomic vulnerability in Grenada, a tropical small island developing state (SIDS) in the Eastern Caribbean. Our model combines spatial features representing variables of social sensitivity, community adaptive capacity, and community exposure to flooding in an integrated vulnerability index. We draw from the fields of climate change adaptation, disaster management, and poverty and development to select our variables enabling unique, cross sector, applications of our assessment. Mapping our results illustrates that vulnerability to flooding is not evenly distributed across the country and is not driven by the same factors in all areas of Grenada. This indicates a need for the implementation of different strategies in communities across Grenada to help effectively reduce vulnerability to climate and coastal hazards. The approach presented in this paper can be used to address national issues on climate change adaptation, disaster management, and poverty and development and more effectively utilize funds in order to reduce community vulnerability to natural hazards today and in the future.

Coral reefs for coastal protection: A new methodological approach and engineering case study in Grenada

Coastal communities in tropical environments are at increasing risk from both environmental degradation and climate change and require urgent local adaptation action. Evidences show coral reefs play a critical role in wave attenuation but relatively little direct connection has been drawn between these effects and impacts on shorelines. Reefs are rarely assessed for their coastal protection service and thus not managed for their infrastructure benefits, while widespread damage and degradation continues. This paper presents a systematic approach to assess the protective role of coral reefs and to examine solutions based on the reefs influence on wave propagation patterns. Portions of the shoreline of Grenville Bay, Grenada, have seen acute shoreline erosion and coastal flooding. This paper (i) analyzes the historical changes in the shoreline and the local marine, (ii) assess the role of coral reefs in shoreline positioning through a shoreline equilibrium model first applied to coral reef environments, and (iii) design and begin implementation of a reef-based solution to reduce erosion and flooding. Coastline changes in the bay over the past 6 decades are analyzed from bathymetry and benthic surveys, historical imagery, historical wave and sea level data and modeling of wave dynamics. The analysis shows that, at present, the healthy and well-developed coral reefs system in the southern bay keeps the shoreline in equilibrium and stable, whereas reef degradation in the northern bay is linked with severe coastal erosion. A comparison of wave energy modeling for past bathymetry indicates that degradation of the coral reefs better explains erosion than changes in climate and historical sea level rise. Using this knowledge on how reefs affect the hydrodynamics, a reef restoration solution is designed and studied to ameliorate the coastal erosion and flooding. A characteristic design provides a modular design that can meet specific engineering, ecological and implementation criteria. Four pilot units were implemented in 2015 and are currently being field-tested. This paper presents one of the few existing examples available to date of a reef restoration project designed and engineered to deliver risk reduction benefits. The case study shows how engineering and ecology can work together in community-based adaptation. Our findings are particularly important for Small Island States on the front lines of climate change, who have the most to gain from protecting and managing coral reefs as coastal infrastructure.

Community-Based Climate Vulnerability and Adaptation Tools: A Review of Tools and Their Applications

Conservation and development organizations conduct vulnerability and adaptation assessments to assess the vulnerability of coastal communities and ecosystems to climate change and to identify adaptation strategies to address these impacts. Local assessments are needed to provide this information at the scale of communities and critical habitats. Over the last decade, there has been a proliferation of tools developed to assess climate vulnerability and adaptation at the community level. However, there has been limited synthesis of the available tools across disciplines in the peer-reviewed literature and limited guidance provided to help conservation practitioners and development planners select which tool is most appropriate for a given application. This article reviews a number of tools designed for community-level climate vulnerability and adaptation assessments and highlights their advantages and limitations to help managers make informed decisions about tool selection. Selection of tools will involve tradeoffs in terms of the capacity and resources needed to apply the tools and the aspects of social and ecological vulnerability that they address.

Assessing risk associated with sea-level rise and storm surge—Redux

Scholarly, peer-reviewed analyses of reasonable sea-level rise and storm surge scenarios are essential to estimate risks to people and property and to identify sensible choices to reduce these risks. Herein we reply to Boretti and Parker, who suggest that sea levels are rising but not currently accelerating. In this respect, they take positions inconsistent with the majority of peer-reviewed semiempirical and model-based sea-level rise projections. Boretti’s comment largely focuses on an analysis of Australian tide gauges. The analysis, text and figures are basically a reproduction of a comment that he has provided previously to a completely different study from the Gold Coast of Australia (Cooper and Lemckert 2012); we are unclear on the relevance of this replicated Australian analysis to our study in the northeast United States. Both Boretti and Parker have drawn conclusions about sealevel rise trends in the United States through ‘visual scanning’ of graphs and by comparing relative sea-level rise trend estimates from years 1999 and 2006. Visual scanning is not a robust method, and it is highly unlikely that any conclusions based on analysis of such a short and particular period of time would pass peer review.

Evaluating alternative future sea-level rise scenarios

We agree with Burton that sea levels are rising. However, we have different opinions about the rate of sea-level rise (SLR) most appropriate for evaluation of future scenarios. Burton argues that the best prediction for sea level in the future is ‘‘simply a linear projection of the history of sea level’’; this is one interpretation, and it assumes that the future will be like the recent past. A linear projection represents a possible minimum expected rate of SLR and is used to define a lower bound on SLR when assessing the effects of SLR on civil works projects in the United States (USACE 2011). Overall, the evidence suggests that sea levels are rising and will rise more quickly and that it is responsible scientifically and in public policy to evaluate more widely accepted alternative future scenarios. Burton argues that because the data he references show no acceleration in SLR, increasing CO2 cannot in the future cause an acceleration in SLR. However, if concentrations of greenhouse gases (GHGs) continue to increase at an accelerated pace, arguing that no acceleration in SLR would occur would mean rejecting well-established chemical and physical processes relating GHGs to global warming and global warming to ice melt