Tropical Cyclone Impacts Along the Bangladesh Coast: Evaluation of Future Impacts and a Methodology for Assessing Local-Scale Dynamic Risk

Abstract

Tropical cyclones (TCs) are highly influential and impactful weather phenomena, greatly affecting both the environment and society. It is well recognized that their activity and physical impacts are likely to be influenced by anthropogenic climate change. The primary objective of this study is to examine the effects of TCs making landfall in the Bay of Bengal and, more specifically, on the Bangladesh coast, both currently and under projected climate scenarios. Additionally, the study aims to develop a local-scale dynamic risk framework specifically designed for TC hazards. To achieve these objectives, an extensive analysis of TCs in the North Indian Ocean is conducted by: 1) analyzing historical TC best-track data spanning from 1989 to 2018 to evaluate TC exposure in the North Indian Ocean. 2) simulating historical landfalling TCs in Bangladesh under current and two future projection scenarios for the 2050s, 2070s, and 2090s using the pseudowarming framework based on climate perturbations from the CSIRO ACCESS-CM2 model. 3) developing an innovative risk framework that combines the impacts of climate change and local-scale socio-demographic scenarios to assess the potential impact of TCs and evaluate their associated risk levels. The findings suggest that there has been a slight decrease in the frequency of TC landfalls in the region over the past 30 years, accompanied by a spatial shift in landfall patterns, with a higher occurrence of landfalling TCs in northern India and western Bangladesh and a decrease in eastern Bangladesh. In the future, results suggest that the central coast of Bangladesh is likely to experience an increase in TC-related hazards, particularly rainfall while the western and eastern coastal regions will experience reduced hazards. Finally, a dynamic risk framework is presented that captures the realistic behavior of district-level socio-demographic indices. The framework is evaluated for a district situated on the central coast of Bangladesh and demonstrates that the risk due to TCs will likely be heightened in that location due to the pressure of increased TC hazards on modeled socio-demographic conditions