Standing on a small pontoon, Elliott lowered herself to guide a hard plastic tube vertically into the water as her colleague, Josh Breggy, bobbed a metal prop driver up and down above her helmeted head. Ching! Ching! Ching! — to bury the tube deep under the lake.
After hours on the water, they used a winch to pull up a 1.5-foot cylindrical section of the lake bed. Tucked between the mud clumps was what Elliott was looking for: a layer of sand, remnants of a terrible storm that had hit West Florida.
“This is a beautiful example of a hurricane layer,” she said., She ran her finger over the clear tube.
This watery, dirty work is part of a field of research called paleometology, which studies ancient hurricanes — a growing, relatively new science that seeks to understand the storms that battered this region and other coastlines before humans began recording the weather with modern instruments.
What researchers have found so far in the ancient mud is sounding a warning. Sifting through the sediments, paleoclimatologists have discovered times when violent storms battered the coastline more frequently than current records indicate. Their work suggests that the oceans could produce hurricane seasons far more ruthless than modern society has ever experienced.
Now, by burning fossil fuels and pumping greenhouse gases into the atmosphere, the world is in danger of repeating those storms. Forecasters are already predicting that this year’s hurricane season, which began on June 1, could be the worst in decades. Hurricane Beryl, which blew up into a dangerous Category 4 hurricane on Sunday, is expected to hit the Caribbean this week.
“If the past is any indication of what’s to come, coastal communities are really vulnerable,” Elliott said.
Searching for ancient hurricanes
In 1989, Louisiana State University professor Kambiu Liu was giving a lecture about layers of ash left on lake bottoms by volcanic eruptions when student Miriam Fern asked whether scientists could also see the scars left by hurricanes.
“So I thought, ‘Of course we can do that,'” Liu said. That summer, he and Fern discovered a layer of sand deep beneath an Alabama lake left by a 1979 storm.
Paleometeorology boomed after Category 5 Hurricane Andrew struck the Bahamas, Florida, and Louisiana in 1992, killing dozens of people and causing billions of dollars in damage. The reinsurance industry, which financially backs homeowners and other insurance companies,, It has funded research into prehistoric hurricanes to better understand the risk of major storms.
“They really took action and kick-started the field,” says Jeff Donnelly, another ancient hurricane researcher at Woods Hole Oceanographic Institution.
Climate scientists don’t have much to rely on to predict how hurricane patterns will change in response to rising temperatures. Approximately 170 years of measurement dataA mere blip in Earth’s history, paleometology has the potential to extend the storm record by thousands of years, painting a more complete picture of how damaging hurricanes are.
When a powerful hurricane makes landfall, the waters crash onto the shore, carrying waves of sand onto the land. If there are lakes along the coast, the sand washes into the lake and sinks to the bottom. By measuring the radiocarbon in these layers, paleoclimatologists can pinpoint when the storm struck.
Over time, the coarse sand deposited by storms can become covered with mud or sandwiched between layers of finer sand. Generally, the more violent the storm, the coarser the sand, because it takes more force to push the heavy sand into the lake.
Finding a hurricane’s layer of sand among other piles can be difficult: “It’s like finding hay in a haystack,” Elliott says.
Elliott knows perseverance: Growing up in Michigan, he studied geology in college and spent summers helping his father build houses, and he says he had some tense conversations with his conservative father about climate change.
But recently, she’s taken the time to explain the data and answer his questions. “We just sat down and talked about it,” she says. “And now, at least he’s open to having the conversation and acknowledging that something is changing.”
Here at Lake Campbell At Topsail Hill Conservation State Park in Florida, only a thin ridge of white sand separates the freshwater body of water. From the Gulf of Mexico, one of the few places in the world with a coastal dune lake, Elliott, a budding ancient hurricane researcher, thought it would be the perfect place to look for signs of ancient storms.
“Coastal lakes are our favorite places to coring,” she said.
After burying the tube in the lake bottom, Elliott and Bregie, a Clemson University scientist, took turns turning the winch and pulling the cylinder by hand, pulling up tiny pieces of the lake’s precious sediment.
“I hope this is mud,” Breggy said. “Keep going, keep going, keep going,” Elliott urged. “We’ve got to get it out.” The first foot-and-a-half of the core contained a layer of sand from a relatively recent storm, probably Hurricane Opal in 1995.
To find older storms, the team needed to dig deeper into the lake bed and further back in time. Because the pontoon doesn’t have a motor, Elliott and Bregie relied on undergraduate students in kayaks and canoes to tow the pontoon across the roughly 100-acre lake.
Far from the shade of the pine trees on the lake’s edge, the small fleet pulled their pontoons towards the middle of the lake. A group of students sat on the edge of the lake, keeping watch for crocodiles.
“Watch your head,” Breggy said, and began thumping another hollow plastic tube to the bottom of the lake. Exhausted, he began to imagine what he’d have for dinner that night. “I’m going to get ice cream tonight,” he said. “And strawberries.”
The next two cores are larger, about 3 and 13 feet long; the longest is probably more than 10,000 years old, Bregie said. Its chalky smell suggests it contains marine microfossils rich in calcium carbonate, which can tell researchers which layers came from the ocean.
Back on land, Elliot and Breggy high-fived.
Other sediment cores along the Gulf Coast reveal a period of intense hurricane activity in the region that was worse than present-day hurricane activity that continued for centuries but came to an abrupt end about 600 to 800 years ago.
What causes storms to rage and then calm down? One theory is that it’s due to shifts in the position of high pressure over the Atlantic Ocean. Bermuda High This could have pushed storms from the Gulf Coast to the East Coast, which could explain the increase in storms on the New England lakes shortly after hurricane activity on the Gulf Coast subsided.
Another factor is Loop CurrentIt flows through the Gulf of Mexico. It once flowed close to the coast but then shifted south into the Gulf, cooling the water and robbing the storm of its wind energy.
The fact that surface temperatures in the Gulf of Mexico are now rising again due to climate change is worrying to those who study ancient hurricanes.
“What these records clearly show is that the climate system is already capable of self-regulating in ways that are resulting in activity not seen in the past century or so, except through human intervention,” Donnelly says. “The big question is, now that we’re actually turning the climate knob, what are the likely outcomes?”
To find the answer, paleoclimatologists are looking beyond the layers of sand for evidence of hurricanes. Droplet Precipitation They searched for lakes formed by cyclonic rains, looked for coral rocks washed up by storms to find lakes, and searched libraries for newspaper clippings, ship logs and diaries documenting hurricanes.
“If you have different technologies and they work together, that may be the best approach,” Liu said.
Much of Elliott and Bregie’s research focuses on tree rings: Hurricanes, at least if they don’t destroy them, leave subtle traces in coastal trees, as the rings record past extreme rainfall and saltwater floods.
Bregey makes every effort to find old wood, harvesting it from leftover stumps and excavated coffins. He recently had a tetanus shot after being pricked by a rusty nail while harvesting wood in an old attic.
“The problem here in the eastern United States is that there’s so much logging,” Bregie says. “It’s hard to find living, old trees.”
Back on shore, Elliot knelt down and used a power tool to cut one of the sediment cores in half. As she ran the tool along the tube, a thin strip of plastic curled up. Always ready to give a lesson, she helped one of her students complete the task.
“Beautiful,” she said, complimenting his work. He stopped, but she encouraged him. “You’re amazing, you’re amazing.”
A series of dark bands in the halved sediment core could be layers of hurricanes, but only thorough lab analysis will reveal the truth: Elliott and Bregie’s lab will be searching for marine fossils, measuring the size of sand grains, and analyzing isotope levels to gauge the strength of ancient storms and work out when they struck.
“This is where our work begins,” Elliott said.
Elliott was at a hotel after a day’s work at Campbell Lake when she called her father. “‘What did you see? What did you learn?'” she recalled him asking.
In a phone interview afterwards, Elliott’s father, Tony Timmons, acknowledged that the climate is changing, but said he “can’t believe it’s all man-made.”If more scientists like his daughter were to study climate change, people might be more likely to accept it.
“Em explains things to me so it’s interesting and I can understand,” he said.
He added: “What she’s doing is important.”