Climate scientists Michael Wehner of Berkeley Lab and James Kossin of the First Street Foundation have presented a hypothetical Saffir-Simpson category 6 for hurricanes with winds greater than 309 kilometers per hour. These experts expose in an article published by the Proceeding of the National Academy of Sciences (PNAS) the expiration of a system used for more than half a century, insufficient in the current global warming scenario. This new category would help improve communication of the risks of stronger and more destructive storms that will spread with rising sea temperatures.
Hurricane formation involves the transfer of heat from the ocean surface to the air in the troposphere. Anthropogenic global warming is causing sea temperatures to rise and, therefore, adding additional thermal energy that contributes to storms. In fact, between 2013 and 2021 there were five storms that would have been classified as category 6 by these scientists: Patricia in Mexico (348 kph) and four other typhoons in Southeast Asia (Surigae, Goni, Merani and Haiyan), with winds of 315 kph.
Wehner and Kossin consider that there is a significant trend towards an increasingly frequent overcoming of the environmental conditions that increase the intensity of hurricanes. To do this, scientists have used state-of-the-art simulators, which have allowed them to compare models with and without the influence of anthropogenic global warming. The results showed that, with a temperature increase of 2 degrees above pre-industrial levels, the probability of Category 6 hurricanes increases by 50% in the Philippines or 100% in the Gulf of Mexico.
Category 6 hurricanes are much more intense, damaging and deadly, posing a real threat to coastal communities in North America or Southeast Asia. This study also points out the obsolescence of the Saffir-Simpson scale in terms of risk prevention, since it only takes into account wind speed and not other factors such as storm surges or inland flooding, responsible for 50% and 27% of deaths respectively. With global warming, they point out, the rate of precipitation also increases exponentially, as does the potential damage from storm surges, which are influenced by the size of the storm and the speed of its advance.
Despite everything, experts are aware of the limitations that this change would bring. “We believe changes in messaging are necessary to better inform the public, and while adding a sixth category to the Saffir-Simpson hurricane wind scale would not solve that problem, it could raise awareness about the dangers of increased risk of large tropical cyclones due to global warming,” they conclude.