Hurricane Otis was a deadly warning about warming oceans – The Virginian-Pilot
Hurricane Otis – which killed at least 48 people after hitting Mexico’s southern coast in October – adds to a devastating hurricane season that has battered the Atlantic and eastern Pacific basins. The Atlantic has had a particularly busy year. Not only has it seen the likes of Idalia and Lee, but it has also seen 17 other named storms so far, putting the total well above the average of 14 named storms per season, which typically lasts from June through November.
Four of the year’s biggest storms hit a wide range of locations: Hillary made landfall on the Baja Peninsula before passing California and Nevada; Otis landed at Acapulco; Idalia affected the southeastern United States. Lee reached New England and Canada. Runoff from Hillary temporarily formed a salt lake in Death Valley, and winds from Idalia brought flamingos as far north as Ohio and Pennsylvania. But all of these storms also had a striking similarity: They intensified unusually quickly as they moved over exceptionally warm water.
Hurricanes require certain conditions to form and thrive. One of the most important conditions is warm ocean water, which is a critical source of fuel for strengthening hurricanes. They allow warm, moist air to rise rapidly through the atmosphere, where this energy is translated into violent thunderstorm activity. Hurricanes need a water temperature of at least 78.8 degrees Fahrenheit; The ocean waters that Hillary, Idalia, Lee, and Otis traveled through were much warmer — about 86 degrees Fahrenheit.
As humans have warmed the planet by burning fossil fuels, the likelihood of extremely warm ocean waters has increased: about 90% of the excess heat generated by human activity has gone into our oceans. The rate of warming of our oceans has also accelerated – on average, ocean surface temperatures rose by about 1.6 degrees Fahrenheit in the period 2011-2020 compared to the period 1850-1900. About two-thirds of this warming has occurred in the past four decades alone.
As ocean surface temperatures rise, it stands to reason that hurricanes will intensify more quickly. In a paper published last month, my research showed that over the past 50 years, this is exactly what we see in the Atlantic Ocean.
It found that the likelihood of modern Atlantic hurricanes intensifying from a small storm (Category 1 or weaker) to a potentially destructive major hurricane (Category 3 or stronger) within 24 hours has doubled compared to the same historical era. The chance of a storm with this type of jump occurring in just 12 hours is more than three times that of a storm. Statistics indicate that these changes would have been impossible if environmental conditions had not changed since historical times.
Although my research focused on the Atlantic, it is not unreasonable to expect similar changes elsewhere. In fact, these findings turned out to be tragically prophetic: Six days after they were published, Hurricane Otis shocked almost everyone when it transformed from a tropical storm into a Category 5 hurricane in just over 12 hours before making landfall in Acapulco.
The hurricanes that have intensified dramatically along the Atlantic and eastern Pacific coasts this year, combined with evidence that this type of force is becoming more common, should serve as a critical warning.
We’re already seeing storms intensify at accelerating rates looking at the data and at events like Lee and Otis. As we saw well with Otis, hurricanes that intensify quickly are often difficult to predict and plan for. Sudden changes may require various protective measures, such as evacuating certain neighborhoods. This means we really have to start improving preparedness and planning in vulnerable coastal communities.
We also know that the rate at which hurricanes intensify has only actually increased in the past 50 years – over a period of significant increases in ocean temperatures due to human-induced global warming. Without major changes in our behavior, including a rapid transition away from fossil fuels, this trend is likely to continue, or even worsen, in the future.
When it comes to a warming planet, we know we’re the cause — which means we can be the solution, too. It is up to us to ensure a sustainable future for coastal communities that are already under threat.
Andra Garner is an assistant professor and climate scientist in the Department of Environmental Sciences at Rowan University in New Jersey. I wrote this for the Los Angeles Times.