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The effects of climate change will be felt by everyone. With planning and preparation, communities can weather and recover from storms and become even better places to live and thrive. Through community-wide planning, cities and townships can actively cultivate their abilities to recover from adverse situations and events, working to strengthen and diversify their local economies and communication networks, increase social capital and civic engagement, enhance ecosystem services, improve human health and social systems, and build local adaptive capacity.

Planning for a more resilient community requires a community vulnerability assessment that is designed to identify and help prioritize adaptation strategies in the community planning process. Vulnerability can mean a model that defines ‘vulnerability’ as ‘exposure plus sensitivity.’(1) Exposure refers to hazards in the natural or built environment, while sensitivity refers to the degree to which a community or certain segments of a community could be impacted by an event. By assessing the potential for exposure to a hazard and the sensitivities of specific populations, maps are generated that identify the community’s areas with relatively greater vulnerability. This tool provides direction for community planners and public health workers in reducing risks to human health in the future by knowing where the areas of vulnerability lie and why the vulnerability exists.

In completing the assessment, factors such as demographics, environmental conditions, locations of critical facilities and essential services, and the built environment are considered. This type of assessment can inform policies, programs, and projects that can reduce identified vulnerabilities, which will inevitably lead to a more resilient community.

Climate change is expected to have many vulnerability-related effects that should be considered in community planning and development (e.g., extreme, heat, high winds, tornadoes). However, for the purposes of this study, the community vulnerability assessment is limited to flooding and and its impacts on housing, critical facilities, and social services.

This chapter provides information regarding climate variability and its relationship to vulnerability as well as a brief catalog of different ways to understand and assess vulnerability depending on a community’s context and priorities. As a way to demonstrate how to analyze vulnerability, this chapter includes an example of three vulnerability components that were relevant to the three climate futures, growth management options, and the community of Grand Haven, Michigan.

Background and Considerations

Climate Variability

As discussed in Chapter 2, “Identifying High Risk Coastal Areas,” the earth has experienced an increase in average air and ocean temperatures, rising sea levels, and a decrease in ice cover. Those conditions are expected to persist as climate continues to warm.(3) The Great Lakes region is projected to experience an increase of 1.8 to 5.4° F in average temperatures by 2050, increases that could cause dramatic change in the Great Lakes climate.(4)

Recent models indicate that the climates of Lake Michigan coastal communities will experience greater increases in temperature during the winter months and at night. There are a variety of weather impacts expected with this change in average temperatures. Some of the potential impacts of climate change in these coastal communities include:

  • More frequent and severe storms
  • Increases in winter and spring precipitation
  • Less precipitation as snow and more as rain
  • Less winter ice on lakes
  • Extended growing season (earlier spring/later fall)
  • Greater frequency and intensity of storms
  • More flooding events with risks of erosion
  • Increases in frequency and length of severe heat events
  • Increased risk of drought, particularly in summer

It is important to note that increased flooding and more intense drought are not mutually exclusive nor contradictory. In the Great Lakes region, scientists are predicting more intense rain events in the fall and winter and more intense droughts in the summer months. These changes in climate could have a number of both positive and negative effects on the coastal communities. For example, an extended growing season could help support new crops and increase crop yields for area farmers. On the other hand, the highly variable weather conditions such as severe storms and flooding mixed with summer droughts present big challenges to farming.

Climate and Vulnerability

Vulnerability can have many components and is often context-specific. As stated, for the purposes of this study, we selected aspects of vulnerability that were more relevant to the three climate futures, the coastal management scenarios, and the Grand Haven community. However, in order to have adequate preparation and planning, communities should identify the aspects of vulnerability most relevant to them and their scenarios. In identifying aspects of vulnerability related to flooding scenarios, communities may want to consider the following issues and questions. We address some of these issues in our analysis.

  • Climate models suggest Michigan communities can expect more frequent storms of increasing severity in the decades ahead. The total amount of rainfall per year is also likely to increase. However, climate models suggest the precipitation will be more concentrated in the winter, spring, and fall seasons and there will be more localized, intense storms at almost any time of year. The potential for substantially larger rain events raises concerns over the potential for harm to human health and damage to buildings and infrastructure.
  • In assessing vulnerability, local officials can evaluate potential exposures as well as sensitivity to flooding. Buildings, roads, bridges, sewer lines and other infrastructure located in a flood zone are exposed to greater risks. Where flowing floodwaters have the greatest energy, structures may be undercut, collapsed or moved, and soils will erode. Even areas outside of an identified floodplain are subject to flooding from heavy downpours. Where the soils have low permeability and physical drainage is inadequate, water will accumulate and cause ponding during large storm events.
  • Different housing types and age of housing can impact susceptibility to flooding damage. For example, mobile and manufactured homes are often particularly susceptible to flood damage because they generally lack a reinforced foundation. Moreover, homes built prior to 1940 used a more porous concrete material for basement construction, so water can flow more rapidly through the foundation making them more likely to suffer from flood damage.
  • Municipal infrastructure plays an important role in protecting homes from flood damage. Communities with an aging storm sewer system or ones where the storm sewer has not been fully disconnected from the sanitary sewer are more prone to damage from an overloaded system in the event of a severe rain event.
  • Locations of key community assets such as community centers or grocery stores may be important to consider as they often provide day-to-day services to community residents.
  • The locations of key infrastructure and assets that could be at risk may be important to identify as these types of facilities could be potentially dangerous or could greatly disrupt community activity. These assets include critical facilities such as utilities and other social service centers and institutions such as hospitals and schools.
  • Major health effects of long-term changes to the climate are predicted for the Midwest Region. Already, people in Michigan are experiencing higher rates of skin and eye damage from increased exposure to ultraviolet radiation, increased incidence of respiratory and cardiovascular diseases, and increased incidence of vector-borne and water-borne diseases. Weather conditions and high heat events exacerbate poor health conditions like allergies, asthma, and obesity.
  • Certain populations may be more at risk to climate change impacts including extreme heat events and flash flooding. Characteristics of vulnerable populations include:
    • elderly
    • linguistically-isolated
    • low-income
    • socially-isolated and living alone
    • low educational attainment
    • minority

(1) Foundations for Community Climate Action: Defining Climate Change Vulnerability in Detroit. University of Michigan. December 2012.

(2) Equity in Building Resilience in Adaptation Planning. National Association for the Advancement of Colored people (NAACP)

Adger, W. N. (2006). “Vulnerability.” Global Environmental Change 16 (3): 268-281. Adger, W. N., N. Arnell, and E. Tompkins (2005). “Adapting to climate change-perspectives across scales.” Global Environmental Change 15(2):77-86.

Polsky, C., R. Neff, and B. Yarnal (2007). “Building comparable global change vulnerability assessments: the vulnerability scop-ing diagram.” Global Environmental Change 17(3-4): 472-485.

(3) Wang, J., X. Bai, H. Hu, A. Clites, M. Colton, and B. Lofgren. 2011. Temporal and spatial variability of Great Lakes Ice Cover, 1973-2010. Journal of Climate 25:1318-1329.

(4) Great Lakes Integrated Sciences and Assessments (2015). Temperature. Web. Accessed July 2015.