Oxfam America - Vulnerability and Climate Change in the US Southeast

This Web site is best viewed with Adobe Flash.

Get Adobe Flash player

Vulnerability and Climate Change in the US Southeast

About this Project

Communities that are the least prepared or able to cope with a natural disaster will be hurt worst by it.

This simple fact is based on Oxfam's more than 60 years of experience as a leading global humanitarian aid agency. The harsh realities of climate change and their subsequent impacts on communities, cities, states, and entire regions means that more frequent and severe hazards associated with climate change, such as drought, flooding, hurricane force winds, and sea level rise, threaten to unravel decades of sustainable, equitable development if we choose to do nothing.

Our goal for this project is to bring a fuller understanding of this issue to the public through a multidisciplinary examination of risks, hazards, and disaster.

Historically, studies about climate hazards and social vulnerability have been conducted in separate silos. The Social Vulnerability Index (SoVI) is the first study of its kind to examine both the potential impact of natural hazards and which populations are most likely to be negatively affected by them. The application of SoVI to climate change-related hazards was developed by Dr. Susan Cutter and Dr. Christopher Emrich at the Hazards and Vulnerability Research Institute at the University of South Carolina. The SoVI statistically examines the underlying social and demographic characteristics of the population and how they negatively impact certain segments with regard to climate change-related hazards.

This research, commissioned by Oxfam America, includes a series of layered maps that depict social and climate change-related hazard vulnerability. The maps assist in identifying hotspots in the Southeastern United States that are at significant risk in the face of four particular climate change-related hazards: drought, flooding, hurricane-force winds, and sea level rise. The specific region of focus is the 13-state area encompassing Alabama, Arkansas, Florida, Georgia, Kentucky, Louisiana, Maryland, Mississippi, Virginia, South Carolina, Tennessee, Texas, and Virginia.

We recognize that both demographic variables and climate models are undergoing continuous improvement. As such, our goal is to demonstrate with rigorous data and analysis the potential impacts of climate change related hazards on socially vulnerable populations, not to present an exact valuation of vulnerability or exposure. We encourage more research on the intersection between social conditions and hazards, so that our adaptation responses will not only protect people from harm, but will address the underlying causes of vulnerability.

Take action Tell President Obama to attend the Global Climate Summit in Copenhagen

About Oxfam

Oxfam America is an international relief and development organization that creates lasting solutions to poverty, hunger, and injustice. Together with individuals and local groups in more than 100 countries, Oxfam saves lives, helps people overcome poverty, and fights for social justice. We are an affiliate of Oxfam International.

Oxfam is funding programs in Louisiana and elsewhere in the Southeastern United States to help those most vulnerable to the devastating effects of climate change adapt and be better prepared for climate-related impacts on their homes and livelihoods.

Learn more: www.oxfamamerica.org

About the Hazards Institute

The Hazards and Vulnerability Research Institute (HVRI), at the University of South Carolina in Columbia, SC, is an interdisciplinary research and graduate and undergraduate training center focused on the development of theory, data, metrics, methods, applications, and spatial analytical models for understanding the newly emergent field of hazard vulnerability science.

In addition to basic research, HVRI facilitates local, state, and federal government efforts to improve emergency preparedness, planning, and response and disaster resilience through its outreach activities. These activities include providing technical assistance to and translational products for the practitioner community as well as training emergency managers in GIS applications.


Oxfam has produced a series of layered maps that incorporate social and climate vulnerability. These maps visually identify counties in the Southeastern US that are "hotspots" of high social vulnerability coupled with high vulnerability to the multiple hazards of drought, floods, hurricane-force winds, and sea-level rise. Indicators of social vulnerability include measures such as race and ethnicity, socioeconomic status, gender, age, employment, education, access to medical services, and population growth. The climate hazards of drought, hurricane-force winds, and floods are mapped based on government data indicating past trends. Vulnerability to sea-level rise is measured based on future climate change forecasts.

This analysis marks the first time that vulnerability to climate-related hazards has been overlaid with social vulnerability information, painting a stark picture of how climate change might disproportionately impact some communities in the US.

The Social Vulnerability Index (SoVI) is a quantitative measure of social vulnerability to environmental hazards. Originally developed in 2003 by Dr. Susan Cutter and her colleagues, SoVI provides a way to measure the difference in social vulnerability across states and regions within states. The application of SoVI to climate change-related hazards was commissioned by Oxfam America in 2009, and developed by Dr. Susan Cutter and Dr. Christopher Emrich at the Hazards and Vulnerability Research Institute at the University of South Carolina.

The SoVI statistically examines the underlying social and demographic characteristics of the population and how they impact certain segments in disabling ways when it comes to climate change-related hazards. In this project SoVI uses 32 variables to define the multiple dimensions of vulnerability—called components—and then adds them up to arrive at a single reference point to measure vulnerability. Eight components account for 74.4 percent of the variation in social vulnerability in the study: wealth, age, race, gender, ethnicity, rural farm populations, special needs populations, and employment status.

The social vulnerability scores, ranging from 12.82, indicating the most vulnerable (Webb County, TX), to -19.76, the least vulnerable (Robeson County, NC), were mapped using a three-class standard deviation method. The standard deviations preserve the underlying distribution of the data (mean of zero and one-half standard deviation on either side). The moderate category represents the mean; the elevated category is greater than one-half standard deviation above the mean; and the low category is more than one-half standard deviation below the mean. This method permits the best balance between interpretation (3 classes) and the identification and visualization of the extremes (high and low vulnerability that are of the most interest).

To facilitate comparisons across counties, all data were from the US Census (2000). The Census 2000 data are the most recently available that represent true counts of the population and their characteristics.

The hazards of drought, hurricane force winds, and floods are mapped based on past data indicating trends. Flood hazard areas were calculated using geospatial data associated with FEMA's National Flood Risk Report (FEMA 2006). Hurricane winds were determined by first obtaining the storm tracks for all hurricanes during the past 30 years (1978-2007) that either made landfall or were located within 100 miles of the U.S. mainland, from the historical hurricane track data archive (NOAA 2007). For drought, one standard measure for measuring the duration and intensity of long-term drought is the Palmer Drought Severity Index (PDSI or PDI). For our analysis, we used values of PDSI values of -4 or below to examine counties with extreme drought conditions. The PDSI monthly means were obtained online from the NOAA Earth Systems Research Laboratory’s Physical Science Division from 1978-2007 for each climate division in the study area (NOAA 2009).

Sea-level rise (SLR) is mapped based on future climate change projections. SLR is a non-linear impact associated with climate change, meaning that we cannot draw assumptions on future vulnerabilities based on historic data. We were able to identify specific hazard zones based on USGS digital elevation model (DEM) data and combine that information with the most recent scientific information for projected SLR in 2100 (recent numbers suggest that sea level rise will be greater than the IPCC projections released in 2007.)[1]

For each hazard, a value of 1 was assigned to all counties in the "limited" category; a value of 2 was assigned for those in the "moderate" category; and a value of 3 was assigned for counties in the "extensive" category. We summed these ranked scores to create an overall score (a ranking of the ranks). Each hazard has an equal weight, since there is no scientific evidence to support differential weighting. The multi-hazard score has a theoretical range from 3 to 12 (a maximum value of 3 for each of the four hazards—flood, hurricane wind, drought, and sea level rise; and a minimum value of 1 for each them, plus a value of zero for sea level rise for the interior counties).

Learn more about hazards and social vulnerability

To more fully appreciate the multidisciplinary tradition at the core of this research, we encourage you to review the literature.

Learn more about climate change and adaptation

Oxfam America is campaigning to create equitable solutions to the climate crisis. We are asking that the US go beyond cutting greenhouse gas emissions by providing financial assistance so that the most vulnerable communities here and abroad can adapt. Learn more at oxfamamerica.org/climate.

What you can do

Your elected government officials need to hear from you. Vulnerable communities will suffer disproportionately from the impacts of climate change-related impacts and disasters. Here are ways that local, state, and national policymakers can take urgent action:

Take Action

Tell President Obama to attend the Global Climate Summit in Copenhagen

Poor people are hit first—and worst—by natural disasters and climate change. People are fighting back by deploying early warning systems, planting better crops, storing grain, building shelters, and replanting trees. But they need our help.

We need your help on this urgent issue—the upcoming global climate summit. We need to make sure the US stands up for poor communities at the summit!


Download reports, fact sheets, and other supporting documentation.









North Carolina

South Carolina





The latest updates from Oxfam America and elsewhere in the media. Members of the press and media are invited to contact us directly for additional information.


Patrick Scully
Press Officer
U. S. Gulf Coast Program
T: (617) 728-2544
E: pscully@oxfamamerica.org

Email Facebook Digg Twitter ShareThis