Step 2: Assess Vulnerability & Risks
Identify climate and non-climate stressors
Consider conditions that can exacerbate hazards.
Imagine for a minute that a town you know experiences an extremely heavy rainfall event. If the stormwater drainage system accepts all the water and drains it away, no problem. Now imagine another heavy rain event: this one is similar to the first, but it occurs on a day when the ground is already saturated. As less water soaks into the ground, the total volume of runoff is higher, and water overcomes the capacity of the stormwater system, resulting in a flood. You can also imagine what might happen if the stormwater system was under construction during the rain event…
Conditions that exacerbate hazards and promote damage are called stressors, and they come from both climate and non-climate realms. Climate stressors include events such as consecutive days of rain and heat waves. One way to identify potential climate stressors is to think back to previous weather- and climate-related events or disasters in your region. Think of all the factors that played a role in causing damage.
Take a step: List any climate-related stressors that could exacerbate hazards, and indicate if their frequency is increasing, remaining the same, or decreasing in your region.
Non-climate stressors include things such as changes in land cover (i.e., development that decreases permeability), construction projects that disrupt natural drainage patterns or traffic flows, and degradation of infrastructure elements. Depending on where you live, these stressors may be increasing or decreasing over time. Drawing on knowledge of your region, think broadly about non-climate stressors you have faced or may face in the future. Imagine some worst-case scenarios during which bad weather or a climate-related event could occur.
Take a step: List the non-climate stressors that could turn threats into hazards. Indicate if the stressor is likely to increase, remain steady, or decrease in your region.
Consider potential tipping points
Assess the possibility that irreversible changes could occur.
Determining which of your group’s assets are most likely to be damaged or degraded by a climate threat can help your group decide where to start. One consideration in the decision is how close each asset may be to a tipping point—a point when incremental change in a system results in a new, irreversible response. Some people refer to tipping points as critical thresholds.
Look back to the potential or historical consequences you identified for each asset-threat pair. In some cases, the consequence you described might be considered a tipping point. Looming tipping points aren’t the only factor groups need to consider when deciding which assets to protect, but the potential for a large change in the system can elevate the level of concern for those assets.
Take a step: Describe situations that could represent tipping points for assets. If possible, give some indication of the probability for reaching a tipping point.
Consider which of your exposed assets are most vulnerable.
Another piece of information that can help groups decide which assets are most in need of protection is a vulnerability assessment. You can view a range of vulnerability assessment reports in the Reports section of this site. Groups facing multiple threats often choose to engage risk management experts to study their systems and report on vulnerabilities. For initial explorations, groups can rate sensitivity and adaptive capacity to categorize assets' vulnerability.
Sensitivity is the degree to which a population or asset is susceptible or resistant to impacts from weather or climate events. For example, two wheat crops in neighboring fields have the same exposure, but if the first crop is a heat-resistant strain of wheat and the second is not, the second crop would have a higher sensitivity to extremely hot days. The vulnerability tab of the prepared spreadsheet has additional examples.
Take a step: Categorize the sensitivity of your assets as high, medium, or low.
Adaptive capacity describes the ability of a system to cope with stress or adjust to new situations. For example, when facing drought, agricultural producers who grow several types of crops that mature at different times of the year can adapt more easily than those who grow only one crop. The vulnerability tab of the prepared spreadsheet has additional examples.
Take a step: Categorize the adaptive capacity of your assets.
Look across the entries you've made for each asset. Consider the full range of ratings and notes in your table to come up with relative ratings of vulnerability. In general, vulnerability will be high when sensitivity is high and adaptive capacity is low, or the potential for reaching a tipping point is high. Conversely, assets with low sensitivity and high adaptive capacity have low vulnerability. The vulnerability tab of the prepared spreadsheet has some examples.
Take a step: Assign vulnerability ratings to each of your assets.
Among the asset-threat pairs in your completed Vulnerability Table (the Vulnerability tab of your spreadsheet), identify the most vulnerable or most important assets to protect. These are the ones for which you will characterize risk.
Characterize the risk from climate impacts
Estimate the risk climate poses to your most vulnerable assets.
To characterize risk, you’ll need to estimate two more characteristics of your asset-threat pairs: the probability of a loss, and the magnitude of the (potential) loss, financial and otherwise. These are the two distinct elements of risk.
To estimate the probability of a threat’s occurrence, consider how frequently it has occurred in the past in your region. Consider also how climate change may change the frequency and/or severity of the threat over time. Tools described on this site can help: you can find tools to explore past and current conditions as well as check applied forecasts.
Take a step: Based on your explorations, estimate the probability of the threat’s occurrence for each asset-threat pair as high, medium, or low.
To estimate the magnitude of potential consequences, consider first if people’s lives are in danger. If lives are at stake, the magnitude of consequences is high. For consequences to property, you can examine county tax records to estimate the value of assets. Be as consistent as possible in estimating value of assets across all sectors.
Take a step: Estimate the magnitude of potential consequences for your most important assets as high, medium, or low.
Based on the two rankings, place your asset-threat pairs in the appropriate section of the risk matrix. Though this matrix is qualitative, the rankings can help your group recognize relative risks to their assets. If you choose to quantify risk, use the equation (probability of a loss) x (magnitude of a loss) = risk.
Can you accept the risk climate presents to your assets?
If your answer is no—your group can't tolerate the level of risk climate poses to one or more of your assets—CONTINUE ON TO STEP 3. If the risk is acceptable, move on to other concerns.
Instructions on these pages encourage you to gather specific types of information. You may find it convenient to download this prepared spreadsheet and use it to record input as you move through the steps.
Access the Steps to Resilience Glossary for definitions and examples of words related to resilience.