(Photo: Chip Somodevilla/Getty Images)

In Gainesville, some 45 percent of gas stations are running dry as of last Wednesday. In West Palm Beach, it's 50 percent. And the price of gas has jumped nearly 30 cents on average—and that's without the widespread price gouging that plagued Florida this past weekend.

These are the tough realities Floridians who evacuated in the face of Hurricane Irma last week even as they begin to return home. An unprecedented six million fled from the Category 5 storm, the largest evacuation in United States history.

The exodus created widespread gas shortages in the days before landfall, with the majority of South Florida gas stations dry by last Thursday. Disabled and abandoned vehicles dotted northbound routes. It was a situation that paralyzed many Floridians who wanted to evacuate, as I found when I called several residents weighing their options. "It's like you're trapped," said Adrienne Willensky of Pembroke Pines, who was terrified of attempting to drive away.

"They knew the hurricane was coming, but where was the back-up gas?" a West Palm Beach woman named Adrienne Beauchamp wondered to me the same day. "Why wasn't Florida more prepared?"

I took her question and others to fuel experts. A car-dependent state with a history of hurricanes, Florida had a week before Irma hit to lay in enough fuel for residents to drive out of harm's way—the choice mode of evacuation. But that wasn't enough time, and the reasons why add yet another dimension to the Sunshine State's deepening vulnerability to climate change.

One Hurricane Too Many

Low-lying, peninsular Florida is in a famously precarious place. One lesser-known vulnerability that the Hurricane Irma exposed is how difficult it can be to move fuel supplies here quickly. Unlike states with more shared borders and freight infrastructure, roughly 97 percent of the refined fuel sold in Florida gets shipped in, from the Gulf of Mexico. Much of it usually come from refineries on the shores of Texas—which were devastated just weeks ago by the second-costliest storm in U.S. history, Hurricane Harvey.

With Texas refineries knocked out of commission because of Harvey, Florida's fuel suppliers were already feeling the squeeze before Irma's path became clear. In fact, as of the week before Labor Day, according to Jim Storey, the business development director of the Georgia-based fuel distributor Mansfield Oil, Florida was trucking some of its own supplies over there to help out Texas. But as Irma predictions shaped up, the flow of fuel out-of-state was swiftly reversed.

Emergency Rerouting

The weekend before Labor Day, as the degree of Irma's threat became clearer, Florida gas suppliers and emergency managers joined to strategize. They knew there would be a run on gas, though it wasn't clear yet which parts of the state would be evacuating. So fuel shipments that could be steered to Florida were diverted from all over. Barges that normally deliver from offline Gulf Coast refineries were rerouted to New York and Philadelphia to bring gas south. Tankers from Louisiana and Mississippi steamed eastward to reach Florida in time, having been delayed by Harvey's fearsome path. One oil trader redirected two European barges destined for Africa to Florida instead. According to Hillary Stevenson, director of oil market research for the analysis firm Genscape, the state took in some 570,00 barrels from Europe ahead of Irma in order to make up for supplies it had lost to Harvey.

Florida Governor Rick Scott also waived weight requirements on trucks and limits on truck driver hours to make sure more gas got to more places ahead of the weekend; truckloads of gasoline flooded in from surrounding southeastern states.

"We were accepting supplies from anywhere that would send it," says James Miller, the director of communications for the Florida Petroleum Marketers and Convenience Store Association, a trade group designated to coordinate fuel supplies with the state in the event of an emergency. "The timing of Harvey and Irma was not ideal."

But all that couldn't keep up with the surge in demand for fuel on Thursday, Friday, and Saturday. Once Governor Scott called an evacuation order for virtually all of South Florida, "everyone in those six or seven counties has a requirement to hop in their cars, fill up their tanks, and move north," James says. "So tons of outages that had been contained to Florida spread north."

Cue the cars sputtering dry on the side of the road, and folks scared to leave their homes at all.

Gas Gouging, or the Hand of the Market?

Fortunately, Irma wasn't a repeat of Hurricane Rita, when dozens died trying to evacuate on Houston's traffic-clogged, gas-less roads in 2005. Florida's transportation officials coordinated this evacuation remarkably well. The state was spared catastrophic damage when Irma's path veered from the biggest population center.

But Floridians were not spared at the gas pump. As of last Tuesday night, more than 9,000 complaints of price gouging—mostly on gasoline and water—had flooded the Florida attorney general's office: Think $5.99 for a a gallon of unleaded.

Gasoline is a futures market; it can be bought and sold based on future contract prices, established by coming supply and demand. Predictions of incoming storms, and the huge demand for gasoline that often accompany them, are "absolutely" factored into those prices, says Stevenson, whose company tracks the price of fuel at "spot racks," the intermediary locations between refiners and suppliers where trucks come to fill up fuel to bring to gas stations.

While many gas chains, companies, and government agencies buy fuel at contract-bound prices, others buy it "on the spot" at whatever the going rate. That price, says Stevenson, increased by 26 cents per gallon ahead of Irma. As of Tuesday, the average price of a gallon is $2.71 in Florida, up more than 44 cents from last month. (That price increase is also due in part to Harvey-related fuel shortages.)

"The pain you're feeling at the pump was not all because of people taking advantage of a dire situation," she says. "Some of it was just priced in, as the price of the underlying commodity."

So it doesn't take unscrupulous gas station owners to gouge drivers at the pump, which the Florida attorney general attentively polices. It just takes basic economics.

Gas Shortages Could Get Worse Before They Get Better

This week, as evacuees try to head home, Florida gas stations are still scrambling to refuel. Florida's ports had to shut down while Irma tore through the state, which means incoming shipments are now running on a delay. Now three of them are back online, but with Houston refineries still incapacitated, meeting gas demand is going to be a challenge for some time. Oil shipments are coming in, but the lights are still out at multiple fuel terminals. Many gas stations remain without power too.

It might be another week before Florida's stations are topped off and back in business, but those recovery efforts could be hampered if Hurricane Jose veers towards a U.S. landfall. "Pardon the cliche, but this was all a perfect storm, with Harvey preceding Irma," Stevenson says. Now, the window to get Florida running again before the next hit might already be closing.

Irma is not the last climate change-juiced hurricane Florida will experience: More storms, and more evacuations, loom in its future. Harvey and Irma's back-to-back blows highlight just how fragile the state's position in the global oil supply chain is—and how profoundly the state, like the rest of the country, relies on this limited (and not readily portable) resource. In transit-deficient South Florida, personal vehicles remain the default mode of evacuation for most of the population. If there is not enough gas for them—and if other climate-related disasters are affecting supply—there ought to be other, more gas-efficient ways of getting out.

But right now, no alternative is perfect. Tesla's remote-controlled zaps to extend the range of certain cars made a lot of headlines, but it also spotlit the current limits of electric vehicles as escape pods: Without more robust charging infrastructure, EVs are risky bets for an evacuees. (And with power outages still widespread, no charge could be just as fatal as no gas.) High-speed rail is coming to South Florida, slowly, but not with the regional connections that would make it a viable escape route ahead a hurricane. Shared mobility services, like Uber and Lyft, are likewise great for short-distance travel—but an on-demand carpooling service designed especially for evacuations, an obvious application of technology that widely exists, has yet to hit the market.

That leaves the bus, that perennially overlooked workhorse of public transportation from Florida to Alaska. Interurban buses are the most energy efficient transportation mode, by far, and local transit authorities in Florida worked overtime to bus car-less evacuees to shelters. But imagine if coordinated bus services—in their own dedicated lanes—had been deployed to move significant numbers of Floridians northward.

That would have left more gas, that most precious emergency commodity, to go around. And there would have been fewer tailpipes spewing the emissions that are fueling climate change—and sharpening the teeth on storms like Irma.

This story originally appeared on CityLab, an editorial partner site. Subscribe to CityLab's newsletters and follow CityLab on Facebook and Twitter.