How the brown ocean effect changes everything we know about hurricanes
When Helene devastated North Carolina, it had been downgraded from a hurricane to a tropical storm. (Sustained wind speed alone is what determines the type and category of a storm.) North Carolina didn’t get the eye of the storm either. That didn’t matter. What devastated North Carolina was the amount and rate of rainfall.
The mountains of western North Carolina were thought to be as climate proof as a place could be. 350 miles from the coast. Over 2,000 feet above sea level. Helene showed us a dangerous aspect of storms that means there are no more climate havens — the brown ocean effect.
Hurricanes become especially dangerous when they can spend extended periods of time over warm water. Conventional thinking and history have shown us that when a hurricane reaches land, the land dissipates its strength and the storm, eventually, fizzles. This is why coasts have historically been in greater danger that inland areas. The brown ocean effect changes that.
When land is warm and saturated with water, as happened in Western North Carolina, it acts as something akin to ocean. While it doesn’t typically kick up the wind speed of a storm like Helene, it provides an excess of moisture and heat. Because the ground is saturated, the massive amount of rain can’t be absorbed. This leads to flooding and landslides. The devastation, loss of life, and high number of missing people in Western North Carolina caused by Helene is partially from the brown ocean effect. The heavy rains dumped on saturated land ravaged everything in their path from houses to infrastructure to power and communication lines. There is even footage of a casket unearthed from a cemetery and carried away by the rushing water.
The brown ocean effect can happen anywhere there’s land. As rains become heavier and more frequent from climate change and global warming, it can take hold in many more places. Every land mass can provide ocean-like fuel for a storm.
At the time of this writing, Hurricane Milton is barreling toward Florida. It’s a Category 5 with winds at 180 miles per hour, spinning over the hot waters of the Gulf of Mexico. Stronger than Hurricane Katrina. Even if it weakens, it still has all that water in it that it will drop when it hits land. Also, weakening in this case may be every bit as devastating as wind because it may slow down and pick up even more moisture from the Gulf. The land in Florida is already saturated, as the land in North Carolina was before Helene arrived. It’s a frightening alignment of circumstances.
On Monday night I watched hurricane specialist John Morales get choked up on air giving the news update on Milton becoming a Category 5. These storms are no longer once-in-a-century, once-in-a-lifetime, and perhaps not even once-in-a-season. This may now be our new normal that is anything but normal.