Modeling the exacerbated natural hazard impacts due to climate change for the island nation of Antigua and Barbuda using HAZUS.

Climate change presents unique challenges to Small Island Developing States (SIDS) such as Antigua and Barbuda. Impacts are exacerbated due to the geographic isolation, exposure to major climate hazards, and size of these islands. Sea-level rise, altered rainfall patterns (extreme precipitation and drought), and storm-surges threaten progress towards Sustainable Development Goals (SDGs). To address these concerns, the Department of Environment (DOE) and the Government of Antigua and Barbuda (GoAB) worked with the Green Climate Fund to fund the National Adaptation Plan Climate Change Risk Modelling Project to quantify potential negative impacts.

The project team incorporated the HAZUS data model and vulnerability functions. Although HAZUS was created for U.S. hazards and building stock, several global organizations have adopted its capabilities for other regions of the world. With sufficient knowledge of the HAZUS model building types, local building practices, and applicable building codes, one can manually adjust the existing HAZUS vulnerability functions to accurately reflect the existing building stock. The hazard is augmented with custom wind speeds from an event set developed by project partners at Kinetic. This event set was modified to reflect projected changes in sea surface temperature (SST) provided by project partners at the UK Met Office. The scale of climate change projection data produced by the Regional Climate Models (RCM) is appropriate for the larger Caribbean islands that have some influence on the models. Downscaled climate change projection data from the Met Office was used to more accurately reflect changes in climate patterns and meteorological parameters. Also, the projected rise in sea level was used to characterize the increased risk of both periodic coastal flooding and increased severity of coastal storm surge to residential communities and key economic assets on the island- specifically the financial services sector and tourist resorts.

The results will estimate the impacts of climate change risk using both a change in the estimated average annual losses (AAL) by decade until 2100, as well as both the increased probability and impact of familiar scenarios- such as a 1% probable event or a significant event in the historic record.