Predicting Future Hurricanes
Paleotempestology uncovers patterns of historical hurricanes, hoping to predict destructive weather of the future.
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This is a riff on a Nautilus newsletter article from June 2023 by Katarina Zimmer.
One Sunday in August 1635, the Mather family was finally about to reach the New World from England when a furious storm caught the ship and its crew by surprise. The cables anchoring the vessel near a group of islands 6 miles off the New England coast reportedly snapped, and the vessel with its dozens of passengers hurtled toward a rocky shore. Fortunately, the winds turned at the last minute and steered the ship in another direction, as their son Increase Mather would later write.
Others weren’t so lucky. According to colony governors in what are now Boston and Plymouth, Massachusetts, the storm drove other ships aground, toppled houses, blew down hundreds of thousands of trees, and caused the sea to swell by up to 20 feet.
[It] was such a mighty storm of wind and rain…as none living in these parts ... ever saw.
Governor William Bradford
Contemporary simulations suggest the Great Colonial Hurricane of 1635 was probably the strongest in recorded eastern New England history. (Sandy, which killed nearly 150 people and caused some $65 billion in damage in the US, was no longer even a hurricane when it made landfall in 2012.) Scientists know about the Great Colonial Hurricane’s impact not only from written reports but also from hidden, physical impressions of the long-ago storm left on the landscape.
They show hurricanes can come in waves across the ages.
At the bottom of a pond, Jeffrey Donnelly, a hurricane scientist at the Woods Hole Oceanographic Institution, and his colleagues found subtle, buried evidence of the storm that almost felled the Mather line. The researchers were collecting sediment cores from Salt Pond on Cape Cod, about a third of a mile from the ocean, which has long been a place of mud. They found a pinky finger-thick layer of pure ocean sand in layers that dated back to roughly 1635. The only thing that could have pulled that much beach material over the sand barrier and that far inland was a truly massive storm.
The cores showed even more storms.
Although written accounts suggest the 1635 storm was the strongest of its time, exhumed samples showed it wasn’t the only one. Donnelly found evidence of 10 major storms in the area between 1400 and 1675—surprising, given that major hurricanes are virtually unheard of so far north today. That hurricanes were much more frequent in the past begs the question of why, and whether these levels of storm activity could someday return.
The birth of a new branch of both science and history.
Paleotempestology—the study of old storms—feels like a tongue-twisting, esoteric subniche of meteorology or oceanography or both, borne from shifty grains of sand and mud. Practitioners hope their new branch of science can use these buried traces of long-gone winds and scanty written accounts to show ancient patterns. Since its birth in the 1990s, it has generated insights into hurricane activity over centuries and even millennia. Like so many important developments in science and history, it had its start with a simple question.
During a 1989 lecture, Kam-biu Liu, a scientist at Louisiana State University, was explaining how ash layers marked the activity of ancient volcanoes when one of his students, Miriam Fearn, asked if hurricanes also left behind detectable traces. This was a possibility Liu hadn’t considered before. That summer, they tested the idea at Lake Shelby, a placid freshwater lake near Alabama’s coast.
I still remember vividly the excitement we experienced when we pulled up our first cores from Lake Shelby and we found a distinct sand layer at the top, which was undoubtedly attributed to Hurricane Frederic of 1979.
Kam-biu Liu
In the following years, Liu collected cores from along the Gulf of Mexico coast and at various sites around the Caribbean. Meanwhile, others were producing cores from other places, including the Northeastern US and from large marine caverns called blue holes in the Bahamas. Virtually all revealed an undeniable pattern: mundane sediment punctuated by layers of sand—some obvious, but many so faint they require close analysis of the grain sizes—which mark the surges of dramatic storms that blew through long ago.
These ancient depository records are generating a far different picture of storm patterns than instrumental records alone, which only go back 170 years—or even written records, which, in the US, trace only a few centuries. A proverbial eye-blink in the history of larger climate and weather patterns.
We already think of this area as being pretty active. But that it has tripled in the past is pretty remarkable and has definite implications for how susceptible this region is to storm activity.
Tyler Winkler, Woods Hole Oceanographic Institution
In the western Atlantic, hurricanes have undergone wild swings, often striking at frequencies that far exceed those in the past couple of centuries. By themselves, the sand layers in individual cores appear random. Paleotempestologists find that, for centuries or millennia at a time, hurricane activity from different sites sometimes lines up. This means that hurricanes are not solely random events but can come in waves across the ages, driven by regional or even global climatic changes, suggesting that the climate system can modulate hurricane activity significantly. The big mystery scientists are trying to solve is why—and what that could mean for us.
To find out, paleotempestologists are digging deeper.
In several cores from around the Atlantic basin, they have discovered a period of heightened hurricane activity in the Atlantic starting around 250 A.D., long before Europeans set foot on the North American continent. Between 250 and 1150 A.D., for instance, Donnelly’s team counted about 20 major storms in the Salt Pond cores, roughly matching a pattern of elevated storm activity in other records from the Gulf of Mexico coast and parts of the Caribbean. What caused this tempestuous outburst across the North Atlantic?
Researchers think it may have to do with the warming of sea surface temperatures in the Atlantic during the Medieval Warm Period—between 950 and 1250 AD, which scientists think a natural uptick in solar radiation drove a slight increase in average global temperatures. They estimate that sea surface temperatures rose about half a degree above the long-term norm around this time.
This correlation between hurricane activity and temperatures is illuminating because, while climate models largely agree that climate change will make hurricanes stronger—as warmer waters fuel them with more energy—there is much less certainty on whether more storms are forming to begin with.
The data from the Medieval Warm Period add to existing evidence that rising temperatures on land and in the ocean play a role in increased hurricane formation. Warmer temperatures can generate more disturbances in the atmosphere. The extreme heat rising off the west coast of Africa—where many Atlantic storms form—can create the kinds of perturbations that can turn into wind-sucking low-pressure systems where hurricanes are often born, fueled by warm ocean waters and humid air.
But temperatures are not the whole story.
Another factor in hurricane formation is wind shear—or its absence. Sudden changes in wind speed and direction can disrupt the upward airflows needed to create a hurricane and simply tear them apart. It’s conceivable that the climate during the Medieval Warm Period produced not only warmer sea temperatures but also conditions that discouraged wind shear—something that some recent studies suggest.
Piecing together this deep historical record of these transient—but powerful—storms is important. Identifying the natural forces that shape hurricane activity will hopefully help provide more accurate long-term forecasts for our era. If hurricanes frequently hit places like New England in the past, they might hit there again. With today’s densely populated coastlines and supercharged hurricanes, the impact might be worse than what early colonists witnessed.
There is still a lot more to be done.
Liu currently likens this young field to paleoanthropology, where biologists try to piece together the story of human evolution from piecemeal records over the past few million years—a femur here, a skull fragment there, some pulp in a tooth. Paleotempestologists hope that their work can answer big questions relevant to the future of hundreds of millions of people living along the world’s coastlines.
The answers may lie in tiny grains of sand, blown in by storms of the ages, waiting for scientists to uncover them and for historians digging into obscure archives, teasing out accounts of storms centuries ago.
The Liberty Bell Files: J Edgar’s Demons
Some people believe there are monsters under their beds. One of those people was J. Edgar Hoover, who saw conspiracies and subversion, perversion and spies all around him. What if he ordered his agents to investigate them all? What if those lists and files were in a project called LIBERTY BELL, investigated by the Special Projects Division, which doesn’t exist either? And what if, in all those non-existent files, there were some real live conspiracies, subversions and spies? An illegal waste of time, of course; could never have happened.
What if they did?
And Finally...
On 14 February:
1929: Alexander Flaming discovers Penicillin at St. Mary’s Hospital, London, England, in a contaminated petri dish. This accidental discovery laid the foundation for the development of the first true antibiotic. It became available to the public only in 1945, but the military used it on military casualties before that time.
1943: German forces under Erwin Rommel attack American forces at Kasserine Pass in Tunisia, forcing them back in disarray. Despite the initial German success, Allied reinforcements and stiffening resistance stopped the advance, and Rommel withdrew by February 23rd.
And today is VALENTINE’S DAY commemorating (or not) this day in 278 when the Romans beheaded St. Valentine in Rome. He’s the patron saint of beekeepers and epileptics, affianced couples, happy marriages and, of course, romance. Gents; ladies; if you forgot that special someone today…
Well, I guess Al Gore was wrong.