An Investigation of Climate Change Effects on Design Wind Speeds along the US East and Gulf Coasts

Abstract

Tropical cyclone (TC) winds control design wind speeds for much of the eastern United States. Those winds are likely to intensify with climate change, but climate change was not considered in the ASCE 7-22 design wind speed maps, potentially causing many structures to be designed with unacceptably high levels of risk. In this study, we investigate (1) the increases in design wind speed due to climate change; and (2) the resulting risk to structures if climate change is not considered. We estimated the design wind speeds for US counties affected by TCs along the Gulf and Atlantic coasts using nonstationary methods based on a set of synthetic TCs (1,000–1,500 year simulations) downscaled from the latest global climate projections (CMIP6) for the high-emissions scenario (SSP5-8.5). It was found that over the 21st century, 50-year return period winds would increase by an average of around 10% along the US Gulf and Atlantic coasts. Depending on the risk category, design lifetime, and year of construction, design wind speeds (targeting lifetime exceedance probability) are projected to increase by an average of 3%–6% for all counties studied and 6%–15% for coastal counties. For Risk Category II–IV structures, depending on the design lifetime and year of construction, 8%–36% of all counties studied and 25%–66% of coastal counties would experience projected lifetime exceedance probabilities that were at least two risk categories too low; for example, in up to 26% of all counties studied and 54% of coastal counties, a Risk Category III structure would be effectively designed as Risk Category I or lower.