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Cascading natural events: The perfect storm

The perfect storm happened in 1991, and the movie version was produced in 2000. The meteorological backstory details a set of unusual circumstances that allowed a nor’ easter to absorb a hurricane and evolve into an unusually powerful storm.  The result of this storm was thirteen deaths and thirty-foot waves pounding the east coast, causing around a half-billion dollars of damage in today’s money. So, cascading natural events led to the perfect storm. 

Another example of cascading natural events occurred in California during the winter of 2017-2018. The autumn dry season was hot and long, triggering wildfires that burned away the vegetation cover, thus leaving the soils vulnerable and exposed. Then seasons changed, and the rains came in full force leading to devastating mudslides in Southern California. Intense winter storms dumped excessive amounts of water onto landscapes with nothing left to hold the soil in place. So, the loss of vegetation decreased slope stability, allowing gravity to do its work. Rain and soil made mud, and mudslides then flowed down slopes and into the valleys taking homes and communities with them.

 Natural disasters are costly

Over the last four decades, the USA incurred almost $1.8 trillion in damages from weather and climate disasters. These costs include a total of 265 separate events where damages exceeded $1 billion. The year 2019 alone saw 14 disasters with hail, flooding, tornados, and severe storms impacting the central-eastern half of the country, hurricanes pounding the East and Gulf coasts, and fires in California. Worldwide, natural disasters kill  60,000 people each year on average.

A review of the ten most costly USA disasters shows that seven of the events were hurricanes, two were droughts, and one was a flood. The total cost of these ten was $719 billion, but the hurricanes accounted for 84 percent of the total ($603 billion). Also, half of these disasters occurred during the last decade (four hurricanes and one drought).

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(Source: Kiplinger – Costs are inflation-adjusted)

Climate: an interconnected web

By definition, the climate is the sum of prevailing environmental conditions like temperature, air pressure, humidity, precipitation, and sunshine. So, weather events are the result of how these various environmental factors interact and interconnect. Weather events feed on a series of factors to strengthen or weaken their energy. When those factors all influence a storm in one direction, they form a series of cascading natural events that propel weather conditions to an extreme, creating a perfect storm.

Hurricane Katrina is a case in point. Hurricanes sweep across the ocean sucking up heat energy from the water; The more heat, the stronger the storm. Once Katrina entered the Gulf of Mexico, it encountered waters that were several degrees warmer than normal. This extra heat was a key environmental condition that catapulted Katrina into the costliest disaster in U.S history.     

Heat is a powerful environmental control in many natural disasters. Warm ocean waters strengthen hurricanes and cyclones. Heat on dry land increase evapotranspiration and sucks moisture from the land, thus promoting droughts where crops shrivel up, and wildfires plague the forest and grasslands. Climate change and global warming now deliver even more heat to the oceans and dry land. This extra heat energy is one factor in creating cascading natural events that morph into costly natural disasters. Remember, the five most expensive U.S. natural disasters occurred in the last decade.


Hurricanes more dangerous than in the past (Source: ArcheanWeb) –  Also:

Wildfires and Mudslides (Source: ArcheanWeb) –  Also:


Climate Change Increases Risk of ‘Cascading’ Natural Disasters (By Farshid Vahedifard Amir AghaKouchak; The National Interest) –  Also:

Billion-Dollar Weather and Climate Disasters: Overview (Source: NOAA) –  Also:

The Most Expensive Natural Disasters in U.S. History (By  David Muhlbaum; Kiplinger) –  Also:

Feature Image: New Orleans after Hurricane Katrina (Modified) – By Infrogmation – Own work, CC BY 2.5,   

William House
William is an earth scientist and writer with an interest in providing the science "backstory" for breaking environmental, earth science, and climate change news.