Understanding the Built Environment’s Contribution to Vulnerability

Abstract:

Evaluated at over a trillion dollars, current estimates of U.S. property at risk of sea level rise (SLR) are staggering. Long-term development trajectories of areas exposed to SLR are not well understood, despite being critical for assessing current levels of vulnerability. Using Zillow’s ZTRAX dataset, we analyze coastal development and land use patterns within SLR zones across the conterminous United States from 1900 to 2010. SLR zones developed faster and have higher structure density than non-coastal urban areas. Regionally, the Northeast developed early, while the Pacific and Southeastern U.S. converged with the Northeast in development characteristics later in the 20th century. The land use composition in the Northeast differs from other regions primarily because, 1) there is less rural land in the Northeast as defined by the United States Department of Agriculture’s population based metrics, 2) the proportion of multi-family housing is greater than in any other region, even across the rural urban continuum. Elements of the built environment such as land use composition or building stock quality may indicate local areas that are more vulnerable both structurally and socially. While exposure has been rapidly increasing and remains high in areas affected by frequent tropical cyclones, our findings suggest that current trends in highly exposed places will not dramatically increase vulnerability. Policy should therefore focus on upgrading existing structures, protecting undeveloped land, and regulating redevelopment.