Hurricane Milton shows there's no 'normal' storm season

It may be hard to believe, but about a month ago, people were calling this year’s hurricane season a bust. Now we’re facing a second devastating storm in less than two weeks. In terms of pure quantity of hurricanes, this may still end up being a fairly normal season. But on a heating planet, "normal" is increasingly dangerous.

As of this writing, Hurricane Milton was churning through the superheated Gulf of Mexico as a powerful storm aimed at Florida’s Gulf Coast, where it threatened to deliver devastating winds and tornadoes, a wall of ocean water and biblical rainfall. Florida’s beaches were still littered with debris from Hurricane Helene, which made landfall just 13 days earlier as one of the deadliest and most destructive storms in U.S. history.

Global heating made both of these storms more powerful than they had to be. On the morning before Milton’s landfall, the research group World Weather Attribution released a report estimating climate change had made the sea surface temperatures fueling Helene 200 to 500 times more likely. The extra energy provided by this heat jacked up wind speeds and the rainfall that flooded supposed climate havens in the Appalachian Mountains hundreds of miles from shore.

WWA hasn’t yet produced a similar report on Milton, but that storm also passed through hot Gulf water, which helped intensify it from a mere tropical storm to a Category 5 behemoth in less than 48 hours, one of the fastest cases of rapid intensification on record. It hasn’t been alone this season; both Helene and Beryl, which hammered the Caribbean, Mexico’s Yucatán Peninsula and Texas in early July, also strengthened quickly because of freakishly warm seawater.

The private weather forecaster AccuWeather has estimated Milton could inflict up to $200 billion in damage and economic losses on top of an estimated $250 billion caused by Helene. That’s nearly half a trillion dollars from just two storms in a fortnight. Helene’s death toll, meanwhile, was recently at 232 people and rising.

Climate-change deniers often argue that the number of hurricanes hasn’t increased noticeably in recent years so therefore climate change isn’t happening. But the relationship between climate and hurricanes isn’t so simple. Many factors influence storm formation, from Sahara Desert dust to how wind behaves over the Atlantic. A La Niña weather pattern in the eastern Pacific Ocean can have a huge influence on hurricane seasons, partly by cutting down on the wind shear that weakens storms.

In fact, the expected arrival of a new La Nina this summer, along with record-smashing ocean temperatures, led forecasters to expect this hurricane season to be active. When Beryl broke records as the earliest Category 4 and Category 5 storm in history, it seemed those forecasts were right.

But then the Atlantic went quiet for several weeks. The combination of La Nina showing up late to the party and an unusually high level of Saharan dust over the ocean helped put an unexpected damper on hurricane formation and led to a lot of scientific head-scratching about why the season was turning out to be quiet. In early September, AccuWeather cut its forecast to 16 to 20 named storms and three to six major hurricanes, down from a March forecast of 20 to 25 storms and four to seven major hurricanes. The new forecast was only slightly higher than the 30-year historical average of 14 storms and three major hurricanes.

So far, this more modest forecast seems to be right on track. There have been 13 named storms and four major hurricanes. Though there are nearly two more months to go in the season, its typical peak is supposedly a month behind us. If you were merely looking at these numbers, you’d call this all fairly typical.

But Helene and Milton, like Beryl before it, have been anything but typical. Even Debby, which soaked the U.S. Southeast as a Category 1 storm in early August, took 10 lives and did more than $1 billion in damage. Climate change may not cause hurricanes, but when they do form, it tends to turn them into blockbusters.

That means anyone in the potential path of a hurricane — which can extend hundreds of miles from shore, as Helene taught us — needs to be prepared for the worst. Homes, businesses, towns and cities must be more resilient. We need to better communicate the dangers to our constituents, neighbors and loved ones and get them to safety more effectively.

We should also think carefully about how and whether we rebuild in places most vulnerable to storms, including making plans for fair and equitable retreat. The climate emergency you might have thought was far in the future is now our baseline.

This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners. Mark Gongloff is a Bloomberg Opinion editor and columnist covering climate change. He previously worked for Fortune.com, the Huffington Post and the Wall Street Journal.