Climate Change: Why 'Grey Swan' Hurricanes May be a Major Problem for Cities in the Future

First Posted: Sep 01, 2015 08:54 AM EDT

Some rare but predictable storms could pose huge risks in the future. Scientists have found that severe tropical cyclones would hit a number of coastal cities worldwide that are widely seen as unthreatened by these powerful storms.

These potentially devastating storms are called Grey Swans in comparison with the term Black Swan. Black Swans are truly unpredicted events that have a major impact. In contrast, Grey Swans are highly unlikely, but can be predicted with a degree of confidence.

"We are considering extreme cases," said Ning Lin, one of the researchers, in a news release. "These are relevant for policy making and planning, especially for critical infrastructure and nuclear power plants."

In this latest study, the researchers examined potential storm hazards for Tampa, Florida, Cairns, Australia, and Dubai, United Arab Emirates. They found that powerful storms could generate dangerous storm surge waters in all three cities. In addition, they estimated the levels of devastating storm surges occurring in these cities with odds of 1 in 10,000 in an average year, under current climate conditions.

For example, Tampa Bay has experienced very few extremely damaging hurricanes in its history. The only time it's been hit by major hurricanes was in 1848 and 1921.

That doesn't mean that this will be the case forever, though. The researchers ran 7,000 simulated hurricanes in the area. They found that, although unlikely, a Grey Swan storm could bring surges of up to roughly 18 feet to the Tampa Bay area. That level of storm surge could dwarf those of the storms of 1848 and 1921.

"With climate change, these probabilities can increase significantly over the 21^st century," write the researchers in a news release.

In fact, in Tampa the current storm surge likelihood is predicted to increase to between 1 in 3,000 and 1 in 1,100 by mid-century.

The findings are published in the journal Nature Climate Change.

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TagsHurricane, Climate Change, Climate, Storm, Climate Models, Ocean, Storm Surge