Helen, the deadliest hurricane to hit North America since disastrous Katrina in 2005, was fueled by human-caused global warming. Extreme temperatures caused by the greenhouse effect added 10% to precipitation and accelerated their destructive winds by 11% to leave a trail of at least 227 deaths, according to the group of scientists grouped together in the World Weather Attribution (WWA).
“The probability of forming a hurricane as intense as Helene has been multiplied by 2.5,” summarize the experts. If previously we could expect an event with these characteristics every 135 years, we now have one every 53 years.
These scientists explain – once again – that Helen fed on the very warm waters of the Gulf of Mexico, which were about 3.6°C above average. “The hurricane intensified rapidly, going from category 2 to category 4 in just a few hours,” shortly before hitting the coast of the state of Florida. The storm traveled 800 kilometers.
Already last April, Colorado State University calculated that, given sea water temperatures, the hurricane season was expected to be “extremely active”.
After this storm passed, more than 150,000 households requested government assistance. Additionally, while the region is still recovering, another extraordinarily strong hurricane named Milton is on its way to Florida and Mexico. It has reached category 4 and is expected to reach category 5. The North American state is preparing for a mass evacuation of people.
Once again, a study shows us that hurricanes will continue to get worse if humans don’t stop burning fossil fuels and, therefore, overheating the planet.
Friederike Otto
— Climatologist at Imperial College London
The attribution work was carried out by 21 researchers from different national weather agencies and universities in the United States, the Netherlands, Sweden and Great Britain. “Once again, a study shows us that hurricanes will continue to get worse if humans do not stop burning fossil fuels and, therefore, overheating the planet,” summarizes Friederike Otto, climatologist at Imperial College London.
This hurricane had sustained winds of 225 km/h upon reaching land. These phenomena have seen their strength, increased by climate change, last longer as they reach the continent, at which point they become more destructive for humans, but where, normally, they should lose their maximum intensity.
Hélène tragically reminds us that coastal areas are no longer the only ones vulnerable to these storms. They pose a growing threat to inland areas
Gabriel Vecchi
— Director of the High Meadows Environmental Institute at Princeton University
However, the reality is that the destructive phase of hurricanes is getting longer. When they hit land with more stored energy, they need more time to weaken. In other words, they spend more hours hitting homes and infrastructure inland. In this sense, the director of the High Meadows Environmental Institute at the University of Princetown, Gabriel Vecchi, insists that Helene “was a tragic reminder that it is no longer just coastal areas that are vulnerable to these storms. “They pose a growing threat to inland areas. »
These scientists introduced the ingredients that lead to ultra-intense storms like Helen into their models to find that climate change was causing winds to speed up by an additional 11 percent (about 13 mph more), which, along with increased rainfall, led to a record flood level in coastal areas which reached 4.5 meters. Many residents had to abandon their homes due to the height of the water.
Looking at the fuel hurricanes, that is to say the additional heat absorbed by sea waters – heat is energy which is then transmitted to storms – this team confirmed that, during the passage of Helene job of this energy added by the greenhouse effect: the gases expelled by human activities trap the heat, which remains mainly on the surface of the oceans. “Global warming makes it 200 to 500 times more likely that such warm seas will be in the path of a hurricane.”
