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Step 2: What is the U.S. Climate Vulnerability Index trying to show?

What is the U.S. Climate Vulnerability Index trying to show?

Learn more about how to make sense of CVI data in this section.

CVI Data Boundaries

The CVI uses a geographical context that corresponds to data availability up to the census tract level. A census tract is a small, typically permanent subdivision of a county or statistically equivalent entity. With an optimal size of around 4,000 people, the primary purpose of census tracts is to provide a stable set of geographic units for the presentation of statistical data such as the U.S. census every 10 years.

A community member’s affiliated community may not directly correspond to the data boundaries of a census tract. Other geographic boundaries, such as a block or block group may be more relevant to a community member’s lived experience, but there is few data available at that scale.

However, due to the magnitude of the environmental and climate issues a community faces, the CVI’s data at the EPA region, state, county, and census tract level still contains crucially relevant information to validate the environmental and climate burdens in a community.

Geography Description
EPA Regions There are 10 EPA regions, each including several states.
States Entire population of a state.
County Entire population of a county, the first division of most states.
Census Tract A small census geography of 1,000 to 8,000 people, often averaging about 4,000.
Geographies chart

Census Geography Categories


Counties and equivalent areas are the primary divisions of most states, Puerto Rico, and the Island Areas. They include counties in 48 states; parishes in Louisiana; boroughs and census areas in Alaska; municipios in Puerto Rico; independent cities in Maryland, Missouri, Nevada, and Virginia; and other entities in the Island Areas.

Census Tract

Census tracts generally contain between 1,000 and 8,000 people with an optimum size of 4,000 people. Census tract boundaries are delineated with the intention of being stable over many decades, so they generally follow relatively permanent visible features. However, they may follow governmental unit boundaries and other invisible features in some instances; the boundary of a state or county is always a census tract boundary. Census tracts are likely the most commonly used geography by statisticians and policymakers.

CVI Data Categories

In order to bolster funding, policy, and advocacy efforts, the CVI represents communities’ lived experiences, broadly defines vulnerability, and uses data to show disparities.

Pulling in 184 sets of data, researchers developed a unitless index score that could be used to rank all census tracts in the U.S. This score provides a way to identify communities with the greatest needs and areas where directed investments can have the most impact at the national, EPA region, state, county, and census tract level. To our knowledge of available environmental justice screening and mapping tools, the CVI offers the most thorough and complete compilation of climate impacts at the census tract level and the highest resolution data available nationally – both historical and projected, direct and indirect.

The CVI’s 184 indicators are grouped at the highest level into two themes: Community Baseline and Climate Impacts. These have 7 domains between them.

Community Baseline data represent the factors and conditions within a community that can limit its resilience to climate challenges.


Factors reflecting baseline or overall state of population health.

Social and Economic

Social and economic stressors that impact community resilience.


Environmental factors that pose a threat to a community’s wellbeing.


Essential structures, services, resources that affect community resilience.

Climate Impacts data represent information about past and future impacts of a warming planet.


Expected changes in community health resulting from warming climate.

Extreme Events

Historical and projected extreme weather event occurrences.

Social and Economic

Social and economic costs and impacts associated with change in climate.

Each of the above 7 domains have subdomains and indicators.

For example, Infrastructure has 6 subdomains. These all have indicators, such as “Energy from fossil fuels”.

CVI National Percentiles

The national percentile offers a holistic understanding of a community’s overall vulnerability relative to their neighbors and the rest of the country. Greater vulnerability corresponds to a higher percentile ranking.

The percentiles and rankings, which demonstrate how communities compare relative to others, help show what drives vulnerability and how to prioritize action. This information can then be used to identify the key issues driving vulnerabilityin a neighborhood, county, state, or region.

For example, of the 77 counties in Oklahoma, this county ranks first in the state for its overall climate vulnerability score. It is also in the 94th national percentile, meaning that 94% of all other counties have less overall climate vulnerability than this sample county.