The effects of climate change will be felt by everyone. But with planning and preparation, communities can weather and recover from storms, and even become better places to live, work, and thrive. Through community-wide planning, cities and townships can actively:

  • Cultivate their ability to recover from adverse situations and events
  • Strengthen and diversify their local economies and communication networks
  • Increase social capital and civic engagement
  • Enhance ecosystem services 
  • Improve human health and social systems
  • Build local adaptive capacity

Planning for a more resilient community requires a community vulnerability assessment that analyzes the municipality’s demographics, environmental conditions, critical infrastructure, essential services, and built environment to identify specific areas that are more sensitive to exposures, making them more “climate vulnerable” (1, 2). By assessing the different exposures and sensitivities across the municipality, decision-makers can prioritise resources for areas with relatively greater vulnerability.

Exposure: the presence of hazards in the natural and/or built environment;

Sensitivity: the degree to which a community or neighborhood is harmed by a specific exposure; 

Climate vulnerability: “exposure + sensitivity.” (3)

The goal of this chapter is to provide direction for community planners, public health workers, and other decision-makers working to reduce future risks to residents by identifying vulnerable areas and understanding why the vulnerability exists. This assessment can inform policies, programs, and projects that can reduce identified vulnerabilities, which will inevitably lead to a more resilient community.

The effects of climate change will be felt by everyone. But with planning and preparation, communities can weather and recover from storms, and even become better places to live, work, and thrive.

This chapter provides information regarding climate variability and its relationship to vulnerability, as well as a brief catalog of different ways to evaluate vulnerability depending on a community’s context and priorities. 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.

For the purposes of this study, this community vulnerability assessment is limited to flooding and its impacts on housing, critical facilities, and social services. However, climate change is expected to have many vulnerability-related effects like extreme heat, increased precipitation, and higher wind speeds that should be considered in community planning and development actions. 

Background and Considerations

Climate Vulnerability

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. These conditions are expected to persist and amplify as climate continues to warm.(4)  By 2050, average temperatures across the Great Lakes region are projected to increase between 1.8 to 5.4°F, which could cause dramatic change in the Region’s climate.(5)

Recent models indicate Lake Michigan coastal communities will experience greater increases in temperature during the winter months and at night. Additionally, 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 is often context-specific and can have many components. For the purpose 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, 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:

  1. Climate models suggest Michigan communities can expect more frequent and more intense storms in the decades ahead. The total amount of rainfall per year is also likely to increase. However, models suggest 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. 
  2. 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. 
  3. 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.
  4. 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 during severe rain events.
  5. The location of key community assets such as community centers or grocery stores may be important to consider, as they often provide important day-to-day services to residents. 
  6. Identifying risk to critical infrastructure like substations is vital, as these areas could be dangerous to the public during storms. Risk to hospitals, schools, and public shelters should also be evaluated, as these critical facilities are typically needed in emergency situations. 
  7. Long-term changes to the region’s climate will likely havenegative impacts on residents’ health. Already, people in Michigan are experiencing higher rates of skin and eye damage from increased exposure to ultraviolet radiation; higher respiratory and cardiovascular disease rates; and more vector- and water-borne diseases. Additionally, extreme heat events exacerbate health conditions like allergies, asthma, and obesity.
  8. Socially vulnerable populations are more likely to be adversely affected by climate change.(6) Socioeconomic and demographic characteristics highly vulnerable to climate change impacts include, but are not limited to the following:
    • The elderly (over 65 years old)
    • Linguistically-isolated
    • Low-income 
    • Socially-isolated and living alone
    • Low educational attainment (i.e. no high school diploma)
    • Minority 
    • Unemployed
    • No vehicle access

Additional social vulnerability characteristics to evaluate can be found in the CDC’s Social Vulnerability Index Documentation.(7)

Methods

Housing Sensitivity and Flood Vulnerability

In many communities, flooding impacts are felt most significantly at the household level. A home’s flood risk is based on its relative location to floodplains and other flooding hazard areas. The household flood sensitivity refers to how well the house structure is equipped to deal with flooding.

As modeled by the University of Michigan, household sensitivity to flooding can be determined by looking at the age of the housing stock and homeowners financial ability to maintain and improve the home, which is approximated using the median household income. As discussed previously, homes built before 1940 generally used a more porous concrete material for basement construction, so water can flow more rapidly through the foundation. Moreover, older homes may be more vulnerable if residents have not had the financial resources to make improvements and upgrades. By looking at median household income as a marker of likely upkeep of the home, an attempt was made to exclude older homes that have been well-maintained and undergone upgrades from our areas of flood damage risk.

The team then identified the flood vulnerability of these structures by intersecting the pre-1940 structures with each climate future to identify which specific structures were at risk (Figure 13). It is important to note that this is not a comprehensive analysis of all types of housing that are at risk of flooding. Other potentially vulnerable housing includes mobile or manufactured homes, or homes connected to an aging sewer system. 

Critical Facilities

In general usage, the term “critical facilities” is used to describe all man-made structures or improvements that, because of their function, size, service area, or uniqueness, have the potential to cause serious bodily harm, extensive property damage, or disrupt vital socioeconomic activities if they are damaged or destroyed.(8) The following facilities were included in our analysis:

  • Emergency response facilities (fire stations, police stations, rescue squads, and emergency operation centers)
  • Custodial facilities (hospitals, long-term care facilities, jails and other detention centers, and other health care facilities);
  • Schools
  • Emergency shelters
  • Utilities (water supply, wastewater treatment facilities, and power)
  • Communication facilities
  • Other assets determined by the community to be of critical importance for the protection of the health and safety of the population
  • Places where 300+ people congregate

In our analysis of Grand Haven’s critical facilities and their relationship with the three climate futures, we found that no critical facilities were at immediate risk (as seen in Figure 14), although several are on the edge of each flood zone.

Community Service Centers

Service centers and institutions like homeless shelters and churches are important in delivering day-to-day support to residents. In the event of an emergency like a flash flood, service centers and institutions are especially important, as they act as community shelters if residents cannot return home. These maps highlight key locations of places where residents may seek temporary refuge in the event of an emergency and the relationship between those places and each of the climate futures.

Communities with high population densities, frequent extreme weather events, or both features are likely to have designated services centers. In the event of flood- or storm-induced power outages, locations with backup power sources like generators are essential.

In our analysis of Grand Haven’s community services and their relationship with the three climate futures, we found that no community service facilities were at risk (Figure 15). However, this analysis does not account for road closures brought on by flooding that may prevent accessing these community facilities. 

A best management practice for a resilient community is to designate community service centers that are accessible, evenly distributed across the population, open 24 hours, and well-known to residents to help ensure universal access.


Other Approaches

Vulnerability can be assessed in a number of ways, particularly when considering that climate change is projected to have wide-ranging impacts. The Background and Considerations section earlier in this chapter provides a number of ways to think about vulnerability with respect to climate change. Ultimately, to conduct a meaningful vulnerability assessment, planning analysts will need to determine the vulnerability aspects most relevant to their scenarios and community.

Additional Resources

Snover, A.K., L. Whitely Binder, J. Lopez, E. Willmott, J. Kay, D. Howell, and J. Simmonds.

2007 Preparing for Climate Change: A Guidebook for Local, Regional, and State Governments. In association with and published by ICLEI – Local Governments for Sustainability, Oakland, CA

Michigan Climate and Health Adaptation Plan 2010-2015 Strategic Plan, Prepared by the Michigan Department of Community Health (2001)

Works Cited

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

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

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

(4) 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.

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

(6) Flanagan, Barry E.; Gregory, Edward W.; Hallisey, Elaine J.; Heitgerd, Janet L.; and Lewis, Brian (2011) “A Social Vulnerability Index for Disaster Management,” Journal of Homeland Security and Emergency Management: Vol. 8: Iss. 1, Article 3.

(7) Flanagan, Barry E.; Gregory, Edward W.; Hallisey, Elaine J.; Heitgerd, Janet L.; and Lewis, Brian (2011) “A Social Vulnerability Index for Disaster Management,” Journal of Homeland Security and Emergency Management: Vol. 8: Iss. 1, Article 3.

(8) Risk Management Series Design Guide for Improving Critical Facility Safety from Flooding and High Winds. FEMA 543 January 2007.