FHWA-HEP-12-010: The Use of Climate Information in Vulnerability Assessments
The Federal Highway Administration (FHWA) memorandum “The Use of Climate Information in Vulnerability Assessments” provides guidance on how to access and use historical climate change information and projections of future climate conditions when performing vulnerability assessments for transportation systems. This memorandum describes several sources of climate information and technical assistance, and provides recommendations on how transportation planners can use this information as they consider their climate-related risks. It also describes some of the methods used in previous FHWA-sponsored pilot projects to estimate impacts of sea-level rise on transportation infrastructure.
The memorandum provides guidance on the appropriate use of historical climate data, indicating that historical climate data can help decision-makers:
- Analyze the sensitivity of the transportation system, provide context for future events, and offer tools for communicating climate risks.
- Provide information about the past performance of transportation systems during extreme weather events to anticipate future system sensitivity.
- Perform sensitivity analyses to identify transportation services and assets that could be vulnerable in the future.
- Identify particular climate variables to investigate more closely under future projection models.
Knowledge of historical variability in temperature and precipitation conditions provide context for judging the magnitude of future climate changes and aid in impact assessment.
The memorandum also provides guidance on sources for historical climate data. Data on temperature and precipitation can be obtained from the National Oceanic and Atmospheric Administration (NOAA) in the form of station data for a specific location or regional climate division data. Data for other climate variables are available from other federal agencies: streamflow (U.S. Geological Survey), snowpack (National Resource Conservation Service), and other meteorological variables (NOAA). Although historical climate data can provide insights into the future vulnerabilities of the transportation system and the types of impacts that could occur, care should be taken when making inferences from historical trends, as future climate impacts are unlikely to conform to the range of past trends.
The memorandum then describes the role of modeling future climate projections to inform vulnerability assessments. Climate modeling typically uses an emissions scenario, a set of assumptions about future greenhouse gas emissions and other factors, to project future temperature and precipitation conditions. These outputs can then be downscaled to smaller spatial scales or translated into projected daily-scale statistics for use in regional vulnerability assessment. While climate modeling can provide valuable information about possible future conditions, there is considerable uncertainty associated with climate projection and outputs should be used in vulnerability assessment with these uncertainties in mind.
The memorandum identifies many resources for acquiring historical climate data and climate model outputs, as well as technical assistance resources for accessing climate data, conducting a sensitivity analysis, or making decisions about the use of climate information. In addition to technical assistance available from federal agencies like NOAA and the Department of Interior, some organizations, such as the North American Regional Climate Assessment Program and the Cal-Adapt project, make downscaled climate information available in simplified formats.
The Appendix of the memorandum presents several approaches for estimating impacts of sea-level rise (SLR) on transportation infrastructure, using examples from the five pilot projects conducted under the 2010 - 2011 FHWA Climate Resilience Pilot Program, each of which considered vulnerability to SLR using different methodologies. The Appendix lists resources for assistance in assessing SLR impacts, including guidance documents on analyzing exposure to SLR, data sources and models for inundation mapping or SLR risk assessment, and examples of regional or local inundation mapping.
This Adaptation Clearinghouse entry was prepared with support from the Federal Highway Administration. This entry was last updated on February 6, 2015.
Publication Date: January 2011
- Assessment guide
- Air temperature
- Precipitation changes
- Sea-level rise