Let me start off by saying there is not enough wine in the world to cope with this month, let alone this year *pours rest of bottle for good measure*. However, this isn’t news. Hurricane Sally is. As I type, the category 2 hurricane made landfall over Gulf Shores, Alabama early this morning with sustained wind speeds of 100 mph, already setting records as the earliest “S”-named storm (18th named storm) to form in the Atlantic this season. This, as 4 other active tropical cyclones (formerly 5) currently call the Atlantic home. Despite the record-breaking nature, Sally crept across the Gulf of Mexico at the leisurely pace of 2 mph. Just so you know, a hamster can literally run faster than that.
Outer rain bands were already present across the Gulf Coast on Tuesday as Sally sat offshore. Because of the hurricane’s snail-like pace causing it to hang around, as much as 2 feet of rain is expected across coastal Alabama, creating a situation The National Hurricane Center (“NHC”) refers to as “Historic, life-threatening flash flooding”. This doesn’t even include the addition of 3 to 5 feet of storm surge on top of that in coastal areas as the strongest part of the storm passes over Pensacola, Florida. I can only hope people who didn’t heed warnings will stay inside. A large swath of up to a foot of rain is also forecast across Alabama and into northern Georgia as the system heads northeast this week.
Unfortunately, we are now familiar with these slow-moving, rain-dumping, catastrophic-flooding types of hurricanes. Most infamously, Hurricane Harvey stalled over Houston for days in 2017, leaving behind over 4 feet of rain. Hurricane Dorian in 2019 similarly crawled over The Bahamas, dropping over 2 feet of rain. This pattern is expected to continue due to our changing climate.
A warmer world means more fuel for hurricanes. It’s like putting a 500 horsepower engine in your Honda Civic. A more meandering jet stream due to the decreased temperature differential between the Poles and the Equator also creates the lack of a steering mechanism for storms. This is what we’ve seen with Sally, as it sat stuck between two areas of high pressure in the Gulf before a wave in the jet stream finally picked it up as it now tracks north-northeastward. This stagnant tendency is to blame for feet of rain and flash flooding.
Hurricanes need 4 main ingredients to form:
- Warm water (and lots of it – at least 80 degrees Fahrenheit)
- Convergence at the surface
- Coriolis force (caused by Earth’s rotation, it curves objects traveling long distances)
- A touch of wind shear
Wind perturbations or waves form over the Sahara Desert and head west over the Atlantic. When the conditions are right (ample warm water, low wind shear), a tropical disturbance can form that can further intensify into a hurricane as it heads westward.
Research has shown that climate change is likely to cause wetter, slower, more destructive hurricanes (as we’re living in real-time with Sally). While scientists are not sure if a warmer climate will increase the frequency of hurricanes, the science does agree that the ones that do form will use the warmer water to grow stronger (and let’s be clear – the science does know, actually). The ocean has already warmed by as much as 1 degree Fahrenheit since the 1970’s. While that may not seem like much, spread it across the entire globe and it’s a massive energy imbalance. This warming has also been accelerating at the rate of about 24% over the past few decades.
Like high octane fuel, these higher ocean temperatures act to supercharge a hurricane’s ability to form and intensify, and also provide more water vapor they can condense into rainfall. A research study found that without the influences of climate change, storms like Katrina and Maria would have had 9% less rainfall, and as a result, less flooding.
As water heats up, it also expands leading to sea level rise. This can worsen storm surge from hurricanes along coastal areas as storms move ashore, causing millions to billions of dollars in damage. In fact, deaths due to hurricanes in the United States are actually decreasing due to advanced warnings and preparation, however, damage is on the rise as people continue to make their homes along the coast, increasing exposure. Adjusted for inflation, damages from tropical cyclones are up 6% per year since 1970. Hurricane Harvey alone caused an estimated $125 billion in damages.
So we have slower, wetter, more destructive hurricanes? Cool, feels right for this year.
As we sit at home sipping a PSL trying to comprehend the wildfires, hurricanes, and a global pandemic all at once, know that we do have some control over the choices we make that could lead to a more sustainable future. 90% of the heat from our greenhouse gas emissions is currently stored in the oceans, but it’s not too late to change our habits. Keep in mind “erratic” is the key word when it comes to climate change. There will be years we might only see one or two tropical cyclones, and others (like 2020) where we’re almost out of alphabet letters to name them. However you put it, 2020 continues to keep us on our toes (and our wine).