The rising impact of tropical cyclones in a warming world

A recent study led by Stanford University has uncovered alarming trends regarding the impact of tropical cyclones on global populations. 

According to the researchers, there is a steady increase in the number of people at risk from tropical cyclones and the number of days per year these storms threaten health and livelihoods. 

Study significance 

With climate change fueling more frequent and intense weather events, this type of research is critical in understanding and responding to these growing threats.

Study lead author Renzhi Jing, a postdoctoral scholar at the Stanford School of Medicine, emphasized the importance of the study. 

“Understanding the demographics of populations exposed to cyclones is crucial for understanding evolving risks,” said Jing. “It’s particularly important for risk mitigation and achieving other socially desirable objectives, such as education and poverty alleviation.”

Focus of the study 

Tropical cyclones, characterized by rotating systems of clouds and thunderstorms, bring strong winds and heavy rain. Traditional estimates of exposure to these cyclones have been regional, lacking a global perspective and failing to consider population vulnerabilities.

For the investigation, researchers from Stanford, the RAND Corporation, and other institutions used a new model to merge demographic estimates with tropical cyclone wind fields estimates. This allowed the experts to create a comprehensive global profile of populations exposed to these storms between 2002 and 2019. 

Critical insights

The study revealed that approximately 560 million people are exposed to cyclones annually and there has been an increase in the number of people exposed across all cyclone intensities. 

The researchers also found that the demographic profile of those exposed has shifted, with a decrease in children and an increase in individuals over 60.

Furthermore, socioeconomically deprived populations are more likely to be exposed to tropical cyclones, and this exposure is more pronounced in higher-intensity storms.

Study implications 

The findings suggest tropical cyclones can worsen existing inequalities, and highlight the need for targeted interventions to support vulnerable groups, noted the researchers.

“Severe storms hit the poor the hardest, and could worsen socioeconomic and health inequalities,” said study senior author Professor Eran Bendavid. “Interventions for mitigating tropical cyclone impacts should address this vulnerability.”

More about tropical cyclones 

Tropical cyclones are intense circular storms that originate over warm tropical oceans. Their formation is fueled by the energy released when moist air rises and condenses, a process that is most efficient when the ocean waters are at least 26°C (79°F). 

Structure

These systems are distinguished by their organized structure, typically featuring a calm eye at the center, surrounded by a wall of thunderstorms that produce strong winds and heavy rainfall.

Life cycle

The life cycle of a tropical cyclone begins with a tropical disturbance, which is essentially a disorganized cluster of thunderstorms. Under the right conditions, such as sufficient ocean heat and low vertical wind shear, this disturbance can evolve into a tropical depression, then a tropical storm, and eventually a cyclone. These stages are marked by increasing organization and wind speed.

Damage

Tropical cyclones are known for their potential to cause significant damage. High winds can wreak havoc on infrastructure, vegetation, and power systems. However, the storm surge – the rise in sea level that occurs as the storm approaches the coast – is often the most destructive element, leading to severe coastal flooding. 

Additionally, the heavy rains associated with these storms can result in inland flooding, and in mountainous areas, trigger landslides or mudslides.

Names

Globally, these storms are called different names based on their location: hurricanes in the North Atlantic and Northeast Pacific, typhoons in the Northwest Pacific, and simply cyclones in the South Pacific and Indian Ocean. 

Category

They are categorized based on their wind speeds, with the Saffir-Simpson Hurricane Wind Scale being a common method in some regions. This scale ranges from Category 1 (least severe) to Category 5 (most severe).

Climate change 

The impact of climate change on tropical cyclones is a growing concern. While it’s not clear if climate change will increase the total number of cyclones, it is expected to intensify the proportion of high-category storms and increase the volume of rainfall they deliver. Furthermore, rising sea levels can amplify the impact of storm surges, leading to more significant coastal damage.

The study is published in the journal Nature.

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