The Atlantic hurricane season was devastating for the United States in 2017. Damage from hurricanes Harvey, Irma and Maria cost the United States $267 billion.
But scientists are now working to find out: Is there a link between those superstorms and our warming oceans? Could this be the new normal?
“I’m concerned when hurricanes are used as the poster child for global warming,” said Dr. Chris Landsea, who is the science and operations officer at the National Hurricane Center in Miami.
“It’s very difficult to say how hurricanes are now versus 100 years ago. We’re still challenged today in knowing how strong a hurricane is, even in 2018,” said Landsea.
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Landsea understands the climate is changing and the oceans are warming, but doesn’t see a direct link to the frequency or intensity of storms.
“There’s periods where it’s busy and quiet and busy and quiet, but no trend,” said Landsea, “There’s no statistical change over a 130-year period. Since 1970, the number of hurricanes globally is flat. I haven’t seen anything that suggests that the hurricane intensity is going to change dramatically. It looks like a pretty tiny change to how strong hurricanes will be. It’s not zero, but it’s in the noise level. It’s very small.”
But many, including the United Nation’s Intergovernmental panel on climate change don’t agree.
At the Massachusetts Institute of Technology, some of the most advanced research on the effects of global warming on extreme weather is being done at their department of earth, atmospheric and planetary sciences.
“You’ll find that in any scientific discipline, there’s controversy. It’s actually what drives the profession forward,” said Dr. Kerry Emanual, an MIT professor, and is one of the world’s leading scientists studying hurricanes. He argues the influence of climate change is much more pronounced.
“Frequency, we see nothing at all. And the best most honest answer is – we don’t know,” said Emanual. “The intensity is a little bit different. Models are more unanimous about that. 30 years ago, a 210 mph hurricane would not have even been possible. Today it’s possible. It might be rare, but you have one where you didn’t have one before. The category fours and fives seem to be increasing.”
It’s a troubling trend, but one that seems to be bolstered by recent research. Rapid intensification usually found in major hurricanes has likely increased in the Atlantic Ocean since 1970 and may be more common due to global warming.
One study shows a 70 mph increase in 24 hours happens only once a century. But by 2100, that same intensification could happen once every five to ten years.
“This cap on wind speed is projected to keep going up so it will become possible to have more intense storms,” said Emanuel. “Some people have talked about coming up with category 6. We may need to do that.”
Storms over the past five years have been continually breaking records around the glove, like Hyann in the Philippines and Patricia in Mexico.
Hurricane Irma, which battered South Florida, set a global record for the longest sustained category five winds.
“We’re all pretty confident that we’re going to see higher incidents of the rare high category events and we’re already arguably beginning to see that,” said Emanuel.
But Dr. Landsea doesn’t share that confidence.
“It shows stronger hurricanes but how much of that is real and how much of that is technology? That’s a difficult question to answer,” said Landsea.
Other recent studies show a trend for hurricanes to move slower, which along with the ability for warmer air to hold more moisture, it can lead to considerably more rain and flooding, similar to Harvey in Houston.
And when it comes to seawater, we can expect to see a higher risk from storm surges.
“We have high confidence in an increased risk from storm surges if only because sea level is going up, that’s for sure,” said Emanuel.
And with many wanting to live or enjoy amenities on the coast, that increases the chances for heavy damage.
“There’s a lot more stuff that can be destroyed if a hurricane comes ashore and the potential for a lot of people to get hurt or killed if they don’t evacuate in time,” said Landsea.
Scientists also fear what they call the “Gray Swan,” a now theoretically possible storm that is stronger than anything ever recorded – one that could decimate a coastal area.
“Tampa is something we’re worried about because it has a large population. It’s very low-lying and they haven’t had a really big storm since the 1920s. We’re all worried about Tampa.”