Has it been twenty years since Hurricane Katrina? Maybe it's high time we rethink our methods of categorizing these devastating storms.

On the 20th anniversary of Hurricane Katrina making landfall in Louisiana, a new approach to hurricane assessment is gaining attention. The Tropical Cyclone Severity Scale (TCSS), proposed by scientists at the University of Miami, offers a more comprehensive evaluation of hurricane risks.

Unlike the traditional Saffir-Simpson Hurricane Wind Scale (SSHWS), which categorizes hurricanes based on their maximum sustained wind speed, the TCSS takes into account factors such as rainfall and storm surge. This shift aims to provide a more holistic understanding of the risks associated with these powerful storms.

Hurricanes have been becoming increasingly deadly and are forming far more rapidly than they used to. This new scale is particularly significant as it recognises that the hazards posed by hurricanes extend beyond just wind speed. For instance, in 2005, Hurricane Katrina, classified as a Category 3 storm based on its wind speed, caused enormous storm surges that led to nearly 2,000 deaths and became the costliest storm in US history. Similarly, Hurricane Florence, classified as a Category 1 storm, produced extensive flooding when it struck the US East Coast, killing 55 people and causing catastrophic damage.

The TCSS lists the hazard-specific categories in addition to the storm's overall category. In a situation where two hazards are rated Category 3 or higher, the final number is increased by one. This adjustment aims to highlight the combined threat posed by multiple hazards, such as high winds, storm surges, and heavy rainfall.

Participants in an online experiment were given 10 fictional hurricane forecasts and found that those who received the TCSS were more likely to correctly identify the main hazard and significantly more likely to evacuate for non-wind-related hazards. This suggests that the TCSS could potentially save lives by helping people make more informed decisions about evacuation.

Some scientists have even suggested introducing a new Category 6 to capture these monster storms. The higher category is important as many people base their decision to evacuate on that number, not just on the details of the hazard. Having complete and satisfactory information about storms is important, as without it, people are more likely to underestimate personal risk or even to move towards inaction.

Collins, the researcher behind the TCSS, expressed optimism that now is the time for change. He believes that the TCSS offers a more realistic representation of hurricane severity, considering other hazards like storm surge and rainfall flooding. He hopes that this new scale will lead to better preparedness and ultimately, save lives.

As we remember the devastation caused by hurricanes like Katrina, it's clear that a more comprehensive approach to hurricane assessment is needed. The TCSS, with its focus on providing a holistic understanding of the risks posed by hurricanes, could be a significant step towards achieving that goal. The paper discussing the TCSS was published in Scientific Reports, further adding to its credibility.

In the face of increasingly frequent and powerful hurricanes, the Tropical Cyclone Severity Scale could be a game-changer in our efforts to prepare for and respond to these natural disasters.

Has it been twenty years since Hurricane Katrina? Maybe it's high time we rethink our methods of categorizing these devastating storms.