Pairing the National Risk Index with climate projections
Understanding your community’s risk from climate-related hazards to better plan for the future can seem like a daunting process. Fortunately, FEMA has developed a series of map products that simplify the first part of this process. Called the National Risk Index(NRI), these maps integrate historical economic losses from 18 different hazards with estimates of social vulnerability and community resilience.
Step 1: Historical Risk
NRI heat wave map
NRI cold wave map
NRI wildfire map
NRI drought map
NRI riverine flooding map
NRI coastal flood map
NRI maps for the 6 climate-related hazards in CMRA.
The NRI provides a variety of scores for each hazard (e.g., heat wave, flood, wildfire, etc.). The exposure component of these scores is based on historical observations—events that occurred in the past. The observations include documented weather events such as the actual temperature measured during a heat wave. Risk Index scores also reflect general conditions such as National Weather Service warnings for excessive heat.
Explore the NRI maps to understand your historic risk for the 6 major climate-related hazards in CMRA.
The CMRA Assessment Tool provides projections for potential future conditions from global climate models. Future conditions are described by a variety of temperature and precipitation variables. The projections cover low and high emissions scenarios during four different time frames. The first time frame is a modeled history for 1976 - 2005.
Chart taken from the CMRA Assessment Tool
As shown in the animation, the modeled history for 1976 to 2005 shows 62 to 74 days per year when temperatures exceed 90oF.
Late this century under a high emissions scenario, projections show 111 to 166 days that exceed 90oF. That is a doubling of days with extreme heat.
Step 3: Connect the Dots
How can we pair these two different datasets?
The key point is that the NRI is based on historical events, and CMRA shows projections for future conditions under which those events may occur.
Consider how the frequency, intensity, or duration of hazards that occurred in the past might change under future conditions. Will the hazards occur more often, at higher intensities, or for longer durations? Knowing what could happen—your potential future exposure—is the first step in protecting the things you care about.
NRI Hazard
Related CMRA variables
Heat Wave
Annual days with maximum temperature > 90, 95, 100, 105oF
Cold Wave
Days with maximum temperature below 32°F
Wildfire
Days per year with no precipitation (dry days); Annual days with maximum temperature > 90oF
Drought
Average annual total precipitation; Maximum number of consecutive dry days
Riverine Flooding
Annual days with total precipitation > 1 inch; Annual days that exceed 99th percentile precipitation
Coastal Flooding
Percent of selected census tract impacted by global sea level rise
In some cases we may not see significant patterns of change.
Here we are looking at the NRI score for riverine flooding in the Southeast United States. You'll notice a variety of scores from very low to very high.
However, many of these areas aren't projected to see significant changes in the number of days with precipitation greater than 1 inch.
So we can infer that exposure to flooding conditions may not change all that much.
In other cases we see significant patterns of change.
If we look at the risk for Heat Waves, historically the Northeast and Midwest United States have not had significant exposure or risk.
But these same areas are projected to see huge increases in the number of days exceeding 90°F by mid-century if emissions are high. Some counties may see up to a 1000% increase, going from almost never having extremely hot days, to having 2 weeks or more per year.
We can infer from this map pairing that since overall exposure increases (more people and assets exposed to high temperatures), risk is likely to increase as well. Especially in areas that lack adaptive capacity such as air conditioning or access to cooling centers.
Starting with an understanding of hazards that caused damage in the past (from NRI), consider how the frequency, intensity, and duration of those events are likely to change under projected future conditions. This can help you connect historical risk with future climate exposure.
As more resources are developed for the CMRA Portal, we'll look to include more tailored products and workflows to support this process and your overall resilience journey.
