Hurricanes, also referred to as tropical cyclones or typhoons, are powerful storms that originate over warm ocean waters. Throughout history, these storms have had lasting impacts on societies around the world. High winds, rain, storm surges, and floods affect lives, land, and livelihoods and have a variety of effects on human health. The direct health impacts of hurricanes include drowning due to flooding and trauma resulting from storm surges, blown debris, and structural collapse. Systems for detection, forecasting, early warning, and communications can give populations time to make preparations before hurricane landfall. Evacuation, shelter use, and other preparedness efforts have reduced mortality from hurricanes in many parts of Asia and the Americas. Engineered defenses such as sea walls, flood barriers, and raised structures provide added protection in some settings. While effective in the medium term, such approaches are costly and require dedicated resources, and therefore they have not been implemented in many at-risk sites around the world. Indirect health impacts of hurricanes arise from damage to housing, electricity, water, and transportation infrastructure, and from effects on social supports, economies, and healthcare systems. Indirect health impacts can include infectious diseases, carbon monoxide poisoning, trauma sustained during cleanup, mental health effects, exacerbations of chronic disease, and increases in all-cause mortality. Indirect and long-term health consequences are poorly understood because dedicated study of specific impacts has occurred in only a handful of settings, and, given the diverse array of societies and geographies affected by hurricanes, it is unclear how generalizable the results of these studies may be. Policy makers face three interlinked challenges in protecting human health from hurricanes. First, climate change is leading to increased hazards in many locations by altering hurricane dynamics and contributing to sea-level rise. Second, patterns of intensifying coastal settlement and development are expected to increase population exposure. Third, unequal patterns of exposure and impact on specific populations will continue to raise issues of climate and environmental injustice. Situationally appropriate strategies to protect health from future storms will vary widely, as they must both address the locally relevant manifestations of hurricane hazards and adapt to the cultural and economic context of the affected population. In some areas, inexorable ocean encroachment may lead to consideration of managed retreat from high-risk coastlines; in others, the presence of very large coastal urban populations that cannot feasibly evacuate may lead to design and use of vertical shelters for temporary protection during storms. New ideas and programs are urgently needed in many settings to address hazards associated with extreme rainfall, rising seas on floodplains and low-lying islands, landslide risk in areas undergoing rapid deforestation, and structurally unsound housing in some urban settings. Policies to reduce greenhouse gas emissions will help reduce long-term risk from hurricanes and sea-level rise. Without concrete actions to address both hurricane hazards and population vulnerabiliy, the 21st century may be marked by increasingly dangerous hurricanes affecting growing coastal populations that will be left with few viable options for seeking safety.
Hurricanes and Health
Caleb Dresser, Satchit Balsari, and Jennifer Leaning
Modeling Tropical Cyclones in a Changing Climate
Tropical cyclones (TCs) in their most intense expression (hurricanes or typhoons) are the main natural hazards known to humankind. The impressive socioeconomic consequences for countries dealing with TCs make our ability to model these organized convective structures a key issue to better understanding their nature and their interaction with the climate system. The destructive effects of TCs are mainly caused by three factors: strong wind, storm surge, and extreme precipitation. These TC-induced effects contribute to the annual worldwide damage of the order of billions of dollars and a death toll of thousands of people. Together with the development of tools able to simulate TCs, an accurate estimate of the impact of global warming on TC activity is thus not only of academic interest but also has important implications from a societal and economic point of view. The aim of this article is to provide a description of the TC modeling implementations available to investigate present and future climate scenarios. The two main approaches to dynamically model TCs under a climate perspective are through hurricane models and climate models. Both classes of models evaluate the numerical equations governing the climate system. A hurricane model is an objective tool, designed to simulate the behavior of a tropical cyclone representing the detailed time evolution of the vortex. Considering the global scale, a climate model can be an atmosphere (or ocean)-only general circulation model (GCM) or a fully coupled general circulation model (CGCM). To improve the ability of a climate model in representing small-scale features, instead of a general circulation model, a regional model (RM) can be used: this approach makes it possible to increase the spatial resolution, reducing the extension of the domain considered. In order to be able to represent the tropical cyclone structure, a climate model needs a sufficiently high horizontal resolution (of the order of tens of kilometers) leading to the usage of a great deal of computational power. Both tools can be used to evaluate TC behavior under different climate conditions. The added value of a climate model is its ability to represent the interplay of TCs with the climate system, namely two-way relationships with both atmosphere and ocean dynamics and thermodynamics. In particular, CGCMs are able to take into account the well-known feedback between atmosphere and ocean components induced by TC activity and also the TC–related remote impacts on large-scale atmospheric circulation. The science surrounding TCs has developed in parallel with the increasing complexity of the mentioned tools, both in terms of progress in explaining the physical processes involved and the increased availability of computational power. Many climate research groups around the world, dealing with such numerical models, continuously provide data sets to the scientific community, feeding this branch of climate change science.
Systems Approaches for Coastal Hazard Assessment and Resilience
Scott C. Hagen, Davina L. Passeri, Matthew V. Bilskie, Denise E. DeLorme, and David Yoskowitz
The framework presented herein supports a changing paradigm in the approaches used by coastal researchers, engineers, and social scientists to model the impacts of climate change and sea level rise (SLR) in particular along low-gradient coastal landscapes. Use of a System of Systems (SoS) approach to the coastal dynamics of SLR is encouraged to capture the nonlinear feedbacks and dynamic responses of the bio-geo-physical coastal environment to SLR, while assessing the social, economic, and ecologic impacts. The SoS approach divides the coastal environment into smaller subsystems such as morphology, ecology, and hydrodynamics. Integrated models are used to assess the dynamic responses of subsystems to SLR; these models account for complex interactions and feedbacks among individual systems, which provides a more comprehensive evaluation of the future of the coastal system as a whole. Results from the integrated models can be used to inform economic services valuations, in which economic activity is connected back to bio-geo-physical changes in the environment due to SLR by identifying changes in the coastal subsystems, linking them to the understanding of the economic system and assessing the direct and indirect impacts to the economy. These assessments can be translated from scientific data to application through various stakeholder engagement mechanisms, which provide useful feedback for accountability as well as benchmarks and diagnostic insights for future planning. This allows regional and local coastal managers to create more comprehensive policies to reduce the risks associated with future SLR and enhance coastal resilience.