When the 2021 hurricane season ends Tuesday, it will do so with a whimper.
The season produced an above-average 21 named storms and seven hurricanes, of which four were major storms. But not a single hurricane occupied the Atlantic or the Caribbean after Hurricane Sam dissipated Oct. 5.
People across Tampa Bay should rejoice in this, since Florida’s Gulf Coast is most susceptible to late-season storms, said Bob Bunting, chief executive officer of the nonprofit Climate Adaptation Center in Sarasota.
“September and October are really our months,” Bunting said.
The only impact Tampa Bay had in 2021 came on July 7, when heavy rainfall caused isolated flooding from Tropical Storm Elsa. That means the region has escaped landfall from a major hurricane for 100 years in a row.
Is it pure luck? Or is it because of the long chain of mountains in Cuba breaking up storms?
There are a number of explanations, but don’t expect them to hold true much longer, Bunting warned. The reason: climate change.
Quite simply, a warmer globe means warmer oceans, he said. And warmer oceans mean more and fiercer hurricanes.
Bunting and others discussed the climatological outlook for Tampa Bay and Southwest Florida in 2030, 2040 and 2050 during a climate conference earlier this month hosted by the Climate Adaptation Center and held at the University of South Florida Sarasota-Manatee campus.
A 2-degree increase in global temperatures, an estimate widely considered conservative over the next 30 years, could cause the average number of hurricanes each season to double by 2050, Bunting said. He also projects that storms could start forming as early as April 1 and as late as Christmas, extending the current June-November Atlantic hurricane season by two months.
A steady rise in global temperatures would also mean more storms and possibly the need to add a Category 6 to the Saffir-Simpson Hurricane Wind Scale, he said. The top category today, Category 5, kicks in when sustained winds reach 157 mph.
Only five Category 5 storms formed in the two decades between 1981 and 2000. In the two decades since then, there have been 14.
Bunting predicts twice as many major hurricanes by 2030 if the globe keeps warming at its current pace.
Warmer weather is especially bad news for anyone living near a coast, of course, but another result of climate change zeroes in on Tampa Bay: the weakening of jet streams.
Now, these upper atmosphere flows tend to push hurricanes west into the Gulf of Mexico. Without them, Tampa Bay is more vulnerable.
It works like this, Bunting said: The stronger a jet stream, the less likely a storm is to round the tip of Florida and head due north into the Tampa Bay region.
Scientist Dr. Timothy M. Hall of NASA’s Goddard Institute for Space Studies also predicts Tampa Bay will experience an increased landfall hazard because of global warming. He said in 2020 he expects our region could have a 30 percent higher chance of a hurricane strike each year by the 2030s as storm paths shift east.
This increase in storm probability is dire for Tampa, Hall said during a 2018 climate webinar, as the region is the most “storm-surge vulnerable” city in the country.
“Tampa Bay’s geometry does not help,” Hall said then. “The bay acts as a funnel and water gets pushed in there and it has a hard time getting out.”
Hurricane Michael in October 2018 missed Tampa Bay, but a storm with similar beginnings might not in the future, Bunting said. Michael caused nearly $26 billion in damages to the Florida Panhandle but brought no significant impacts to Tampa Bay despite initial forecasts that it might make landfall here.
Also looming is the prospect that storms will undergo more rapid intensification — an increase of at least 30 mph in 24 hours — just before landfall, he said.
This is growing more common with gulf storms because rising ocean temperatures act as “jet fuel” for storms, Bunting said. In the future, higher water temperatures will enable storms to bounce back even after they’ve been weakened by sustained contact with the mountains of Cuba.
“We could have a tropical depression in the southeast Gulf of Mexico, north of Cuba, and it reaches hurricane strength in a day or two as it approaches our coast,” Bunting said. “I expect the risk of this to rise in the 2030s. I’ve always said Cuba has saved our back because hurricanes have to go over Cuba before it hits us. That’s not necessarily true in the future.”
How can Tampa Bay deal with this grim scenario?
By itself, there’s little the region can do about climate change. Preparation, however, is within its power, Bunting said — spending billions to upgrade infrastructure and halting construction on any land that is 5 feet below sea level.
Preparation is the way to avoid the fate of New Orleans, blindsided by Hurricane Katrina in 2005.
“In this country, we’re great at reacting to disasters and terrible at preparing for one,” Bunting said. “It’s a uniquely American trait, and we have to be better. We have to put that in the past and begin to prepare.”