Assess Vulnerability and Risk

Sensitivity

If an occurrence of a hazard could have a large negative impact on an asset, its sensitivity to that hazard is high. If the hazard is less likely to result in significant damage, its sensitivity is low.

Examples

• A fully stocked furniture store sited on a river floodplain would be highly sensitive to flooding.
• Outdoor recreation fields used for soccer or football generally have a low sensitivity to flooding.

Adaptive Capacity

Even if an asset is sensitive to a hazard, it is not necessarily vulnerable. If the asset has some adaptive capacity—a characteristic that helps it deal with or adjust to the hazard—it can reduce the potential impact on a sensitive asset. 

Examples:

• A furniture store that has flood barriers installed at every door to the building has high adaptive capacity.
• Elevated homes that keep infrastructure and belongings above flood waters have high adaptive capacity.
• Ground-level buildings without flood barriers have low adaptive capacity to flooding.

The exercise described above is an initial screening to help you identify which of your assets is most vulnerable to climate-related hazards. 

For assets that have high or medium vulnerability, you'll also want to characterize the risk they represent. As your low-vulnerability assets are less likely to be damaged, the risk they represent will be proportionally low.

Estimate the probability of a hazard occurring

For the hazards that could impact your most vulnerable assets:

• Collect information on how frequently the hazard has occurred in your region in the past. 
• Is that frequency changing? Check if climate change or other stressors are likely to change the frequency or severity of the hazard over time.

To find out, explore tools tagged for Assess Vulnerability & Risk. Use filters on the left of the Tools page to zero in on your region and on specific assets and hazards.

Based on what you find, estimate the probability a hazard will occur as low, medium, or high. Develop a simple rule set for the three categories to ensure that you apply probability consistently.

Example rule set for categorizing probability:
If a hazard seems likely to occur within 5 years, designate it as a high probability. Categorize events that are likely to occur just once in 5 to 20 years as medium probability. Designate events that are likely to occur less frequently than once in 20 years as low probability.

Estimate the magnitude of a loss

Gather available information to help you estimate the financial and/or social costs of the loss you would experience if the hazard occurs. To get started, explore the losses that resulted from recent hazards in other places or find out what it took for communities to recover from hazardous events that occurred a decade or more ago.

Again, develop a simple rule set to help you categorize the magnitude of a loss as low, medium, or high.
 

Should your risk assessment be qualitative or quantitative?

As directed in these pages, communities often begin using qualitative methods for their assessment, categorizing vulnerability and risk as low, medium, or high. This approach is fairly quick and effective for identifying which assets represent your highest risk. When setting priorities for the most important parts of a complex system, however, groups often choose to do the extra work it takes to quantify vulnerability and risk.

To zero in on specific locations where resilience-building can benefit the entire community, many groups choose to access detailed spatial information and quantitative data on hazards and property values. To work in a real community, this quantitative information about physical assets needs to complemented by social awareness and a commitment serve the entire community.

Quantitative geospatial information may be available as web-accessible map layers. Data available in this format make it relatively easy to calculate and display measures of vulnerability and risk across the community. Maps produced using these methods can display the severity of potential hazards and highlight locations where risk is high. Using a map-based quantitative approach also helps reduce uncertainty, making it easier for your team and decision makers to set priorities.

Check FEMA's National Risk Index

Maps in the National Risk Index give users a way compare data related to occurrences of 18 natural hazards across the United States. Access the interactive online mapping application from FEMA to check your community's status. Learn more in the National Risk Index Primer.

Where should you start?

In general, groups choose to address their highest risk first. However, if you recognize that damage to a specific asset (for example, a heavily used bridge or your telecommunications capacity) could initiate multiple failures across other sectors in your community, consider that asset as a top priority. Think about the things your community truly depends upon to function, and use that knowledge to set your priorities.

Do you need to hire a consultant?

Be aware that many communities choose to hire consultants, adaptation practitioners, or Architecture and Engineering (A&E) firms to assist them in compiling their vulnerability and risk assessments. Professionals who fill these roles still need plenty of input from the local champion and team, but they can help groups navigate unfamiliar concepts and document the most pressing potential climate problems in your community.