Last week was the 10th anniversary of Hurricane Katrina, the hurricane known as the most destructive in the history of the United States. However, a new study has revealed that Katrina wasn't the worst storm that hit the country, or any other country for that matter.
In fact, three global cities were particularly at risk, according to the researchers. They are Tampa in Florida, Cairns in Australia and Dubai in the United Arab Emirates. These cities are at risk of experiencing a storm worse than anything before seen in history.
In a new study in Nature Climate Change authored by Princeton and the Massachusetts Institute of Technology researchers, the city of Tampa was singled out as one area that could potentially be hit by devastating storms called "gray swans." Unlike "Black Swans," which are unpredictable storms, gray swans can be predicted, reported the Christian Science Monitor.
Tampa has been singled out as particularly at risk due to the fact that it's situated on low-lying land and is surrounded by a bay of shallow water, reports Smithsonian Magazine.
"We are considering extreme cases," said Ning Lin, an assistant professor of civil and environmental engineering at Princeton. "These are relevant for policy making and planning, especially for critical infrastructure and nuclear power plants."
The study's purpose is "to raise awareness of what a very low probability, very high impact hurricane event might look like," according to MIT's Kerry Emanuel .
The researchers came up with the gray swan storms through generating a computer model that "coupled" together an extremely high-resolution hurricane model that comes with a global climate model. Researchers were then able to populate the simulated global climate model with different kinds of storms.
"When you do hundreds and hundreds of thousands of events, you're going to see hurricanes that are unlike anything you've seen in history," said Emanuel, who is the key theoretician behind the equations that identify the "maximum potential intensity" of a hurricane in an assumed climate.
Indeed, in the past, Emanuel has published a theoretical "hypercane" with winds close to 500 miles per hour. This is reportedly possible in cases where an asteroid hits Earth and heats up oceans radically fast and far from normal temperature.
With the new method used in the recent study, the researchers were able to show that a worse storm than what had occurred before, like Katrina, is possible, especially with global warming and continuing sea level rise, according to The Washington Post.
During their research, the scientists simulated 2,100 possible Tampa Bay hurricanes with the world's current climate. Then they simulated 3,100 possible hurricanes each for three time periods - 2006 to 2036, 2037 to 2067 and 2068 to 2098, but this time the climate they used were with unchecked global warming climates.
With the world's current climate, the researchers found that a 5.9-meter, or 19-foot, storm surge is possible with a Category 3 hurricane. With a late 21st century climate with a chaotic global warming scenario, the worst-case generated by the study's model depicted a unique storm track, moving north in Florida's Gulf Coast, then swerving inland at Tampa. This simulation generated an 11.1-meter, or nearly 37-foot, storm surge.
As for Dubai, Abu Dhabi and Doha in the Persian Gulf, the researchers were surprised with the results. While the shallow and warm waters of the Persian Gulf appeared like fuel to a cyclone, no cyclones have ever been observed to make it into the Gulf coming from the Arabian Sea. However, according to ARS Technica, in 2007, Cyclone Gonu came close.
The simulated "gray swans" may be highly unlikely - in fact, less than 1 in 10,000 years - but with global warming shifts in recent years, odds rise as well.
In the end, it's still the public's decision whether there is cause for worry. However, it is true that studies such as this will be able to help cities understand, and therefore prepare for possible risks in the future. Knowing how big "gray swan" hurricanes are is still useful, and as the world warms and sea level rises, risks do change.
"With climate change, these probabilities can increase significantly," the researchers wrote in the study. Odds for Tampa increase 1 in 3,000 and 1 in 1,100 by 2050, and between 1 in 2,500 and 1 in 700 by the century's end.
