By Rick Knight and Ed Ignatoff, Citizens’ Climate Lobby
An important point is missing from the debate about evacuation warnings in Southwest Florida ahead of Hurricane Ian. That is, better tools are available for communicating the power of approaching hurricanes and if given greater visibility, perhaps more people would have fled.
Consider that like Hurricane Ian, Hurricane Charley also was a Category 4 when it hit Southwest Florida in 2004, yet Charley would have fit inside Ian’s eye and its devastation will be far exceeded by Ian’s.
The Saffir-Simpson hurricane scale, which ranks storms from Category 1 to 5 according to maximum sustained wind speed, was introduced in 1973 to help predict structural damage. But this metric tells us nothing about the overall size of the storm, how long it will last or what to expect in terms of rainfall, flooding or storm surge.
Meteorologists have since developed metrics that tell us much more. One example is Integrated Kinetic Energy (IKE), introduced by NOAA in 2007. It conveys a storm’s total energy in terajoules (TJ). The IKE for Hurricane Ian has already been calculated at 47 TJ — almost seven times the energy of Charley (7 TJ.) Ian’s energy also was more than two times greater than 1992’s Andrew (20 TJ). Andrew also was a Category 5 storm when it hit southeast Florida and became what was then the costliest hurricane to make landfall in the U.S.
The inadequacy of Saffir-Simpson to comparatively communicate the destructive power of storms doesn’t stop there. In 2005, Hurricane Katrina — a Category 3 when it hit New Orleans, though it was a Category 5 for a while over the Gulf — reached an unprecedented IKE level of 121 TJ. But in 2012, Katrina’s intensity was exceeded by Superstorm Sandy, which measured 141 TJ, yet was considered a Category 1 storm when it hit New Jersey.
Another useful metric, developed by private company StormGeo, is the Hurricane Severity Index (HSI). This 50-point scale combines maximum wind speed with the size of the wind field. As one example, a StormGeo graphic compares the different impacts of two Category 3 hurricanes — Ivan and Dennis — which hit a similar part of the Gulf coast in 2004 and 2005. Dennis (HSI = 18) caused $4 billion in damages. Ivan (HSI = 32) caused $26 billion.
So why do we hang on to the Saffir-Simpson scale? Simplicity and familiarity, it’s said. Or put another way, “That’s how we’ve always done it, so if it ain’t broke, don’t fix it.”
But in these days of tropical cyclones characterized by larger size, more rainfall, rapid intensification and a propensity to linger longer, I say it is broke and it does need to be fixed.
People in hurricane zones might be misled to hear that a storm may be “only” a Category 2 or 3, when it may pose a far bigger risk than a Category 4 or even 5, depending on characteristics not captured in those categories.
Better information could literally be a matter of life or death. Clinging to “how we’ve always done it” is a poor excuse for failing to improve how people today are informed about the power of a storm.
Rick Knight and Ed Ignatoff are volunteers for Citizens’ Climate Lobby, a non-partisan, grassroots organization dedicated to empowering everyday people to work together on climate policy. Rick is CCL’s research coordinator and Illinois state coordinator and Ed is the Boca Raton CCL chapter leader.