How Climate Change is Intensifying the Ferocity of Hurricanes - Episode 99

After the devastating impacts of Hurricanes Helene and Milton over the past few weeks, it's a good time to review the science on why (and how) warming sea temperatures are affecting the intensity of these mega storms. Big, intense tropical cyclones are a part of our future and we should understand why today's storms are so much more powerful than those of just a few decades ago.

For further research:

"Are hurricanes getting worse? Here’s what you need to know" - NPR

"Yet another hurricane wetter, windier and more destructive because of climate change" - World Weather Attribution

"Why Hurricane Milton Got So Strong, So Fast" - NY Times (video)

"A Force of Nature: Hurricanes in a Changing Climate" - NASA

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Transcript

This is Eight Minutes – a podcast helping you understand the energy and climate challenge in just a few minutes – I’m your host, Paul Schuster.

With hurricanes Helene and Milton causing so much destruction across Florida, Georgia, North Carolina and other Southern States – maybe it’s a good time to look at the connection between climate change and these extreme weather events. I think it’s been established that the warming ocean is causing more catastrophic conditions – but how, exactly, is the rising sea temperature contributing to bigger hurricanes?

Let’s look deeper into the science of why climate change is creating once in a lifetime storms seemingly every year or so, now.

Eight Minutes – it’s how long it takes the sun’s rays to hit earth – or about the time it takes for the government’s double super top secret weather control agency to covertly create and guide the next Atlantic hurricane toward the Gulf Coast … kidding, obviously … thought it’s a shame I have to remind anyone that the only control we have over the weather is in how much warming we subject the earth to. 

Let’s get it on.

There has been a lot of research into the rising intensity of oceanic cyclones over the past few decades, as the global ocean water temperature has risen. And these big storms are having devastating impacts on coastal – and even non-coastal communities. Parts of New Orleans continue to lie dormant after hurricane Katrina. Puerto Rico is still recovering from the full impact of hurricanes Maria and Irma. New York isn’t likely to forget the storm surge and flooding from Super Storm Sandy. And the recent Helene devastated mountain towns in western North Carolina and Georgia that thought themselves somewhat protected from climate change.

The reality is that storms ARE getting bigger. According to the World Weather Attribution group, the most damaging hurricanes are around 2 and a half times more likely to occur today than they did 100 years ago. 

The observational data is proving this out. Back in the ‘70’s, there were 16 MAJOR hurricanes, storms classified as Class 3, 4 or 5. In the 80’s, that had risen just slightly to 17 major storms. The 90’s saw it rise to 25 and the 2000’s it rose to 35, more than twice the number observed just two decades earlier.

This decade has already seen even MORE major hurricanes, with the Atlantic recording 20 such storms already – and we’re not even to the halfway point of the decade, yet.

Here’s the thing. The INTENSITY of hurricanes is increasing because of climate change – but the overall NUMBER of storms, isn’t really changing very much. Since 1985, the yearly number of storms has stayed pretty much at around 80 tropical cyclones per year. Climate change isn’t increasing the FREQUENCY of storms – but it IS changing what used to be smaller storms … into behemoth cyclones of devastating intensity.

To understand why, we should get a sense as to how hurricanes form in the first place. These storms need four ingredients to form, stabilize and begin to grow. They need 1) warm ocean water somewhere over 80 degrees Fahrenheit. 2) a LOT of moisture already in the air. 3) low vertical wind shear, which is the measure of the change in wind speed and direction with height. A low wind shear means that storms can develop vertically and maintain a organized structure, whereas too high of a wind shear and the hurricane kinda tips over on itself and fizzles out, like a spinning top on a table top. And, the last component hurricanes need to develop is a pre-existing disturbance, like a cluster of thunderstorms, that can catalyze the storm in the first place.

Climate change is most impacting the first two of those criteria. Atlantic ocean currents are consistently increasing in temperature, providing the fuel, if you will, for these big storms. And it’s not just at the surface, but also at depth. The NY Times reporter Raymond Zhong has a wonderful explanation on how the circulating pattern of hurricanes pick up intensity from the warm water on the surface – but that water is typically replaced by cooler water from below. In past decades, this cooler water from depth would act as something of a break on how fast and how intense a hurricane could become. But as DEEPER ocean water has started to heat up, it’s meant that hurricanes are now seeing something of an almost unlimited fuel supply of warm water that just builds and builds the magnitude of the storm.

The other factor driving these hurricanes is the increasing amount of water vapor being stored in the air. Warmer air temperatures can hold more water vapor. Our warming climate is creating ideal conditions for these giant storms to really unleash themselves.

And while the sheer size and magnitude of these hurricanes are getting bigger, there are a couple of other issues that climate change is driving as well. For one, these storms are developing faster, over a greater geographical area, than ever before. 

Meteorologists use a term called “rapid intensification” to refer to how quickly a tropical storm can organize itself and move from a category 1 or 2 hurricane into something more major. In the case of Milton, the hurricane caught many in the weather community by surprise by so quickly intensifying from a Category 1 to a Category 5 hurricane within a 24 hour period. This … was unprecedented … and suddenly shifted how local authorities and crisis responders were preparing for the storm. What looked like “bad” damage – now suddenly looked catastrophic.

The rate at which hurricanes speed up has increased every decade since the 1980s. A recent study found that rapid intensification has increased by about 4 and a half miles per hour each decade. And that has real implications on the size, scale – and ability to react to these dangerous weather events.

The other condition that we’re seeing more with Atlantic hurricanes is that they’re moving slower. Which is devastating for communities caught in their paths, because a slow moving hurricane now dumps more rain and causes more destruction than a faster one would have. 

To be fair, it hasn’t been proven that a warmer climate is directly causing these slower moving cyclones, though a leading theory is that the warmer air is acting as something of a slowing force on the hurricane. More research still needs to be done.

These slower moving, higher wind intensity storms are incredibly powerful. Not just in the wind damage, but in overwhelming storm surges like what we saw with Sandy in New York or Milton in Tampa. 

But, even inland communities aren’t fully immune. The reason Helen was able to travel so far inland with such force is because the land surface temperature was elevated and the ground was already saturated with moisture from previous storms. It acted as something of a “brown ocean effect”, where, instead of the hurricane losing steam once it reached land, was able to feed off the saturated ground conditions to drive ever further inland. Something that, with climate change warming EVERYTHING around us, we may start to see happening more frequently.

Look, climate change is having an impact on so much of our daily lives, from drought conditions to wildfires … but the magnitude and force of tropical hurricanes may be the most terrifying. These storms are causing tens of billions of dollars of damage and the really big storms are getting bigger – and bigger. They’re slower than ever, causing more destruction over a greater range – and it doesn’t look like they’re going anywhere anytime soon. The best we can do is to prepare, protect … and do what we can to reverse the conditions that have created these monsters in the first place.  

I’m Paul Schuster – and this has been your eight minutes.