This article originally appeared in Hakai Magazine.
Two weeks after Hurricane Fiona made landfall in Atlantic Canada on September 24, 2022, Jeff Ollerhead found himself staring at an upended boardwalk in Prince Edward Island National Park. Damaged by the storm—one of the strongest cyclones ever recorded in Canada—Greenwich Beach was still closed to the general public. Ollerhead, a coastal geomorphologist at Mount Allison University in New Brunswick, cautiously navigates around the ruined boardwalk and a large pond to reach the sand dunes bordering the ocean. “The whole thing had been scarped,” he says, describing how waves carried away large amounts of sand from the seaward side, resulting in the dune’s normally sloping face becoming nearly vertical.
The damage Ollerhead witnessed last fall was dramatic yet not unexpected. As a scientist who studied the Greenwich Dunes for two decades until 2015, he knew that the dunes had endured similar devastation in the past. “Greenwich was completely wiped out by a series of storms 100 years ago and took decades to regenerate,” he explains.
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In the face of climate change and its interaction with storms, scientists strive to understand the consequences of reduced recovery time for dunes.
Dunes are formed when wind deposits sand and shapes it into mounds. Greenwich Beach boasts a roughly six-kilometer stretch of dunes, held in place by vegetation on top. During storms, rows of dunes serve as barriers, shielding inland areas. Although a few of Hurricane Fiona’s powerful waves surpassed the crest of the Greenwich Dunes, the sand prevented the storm surge from causing flooding. The waves eroded the dunes, but the sand acted as a defense mechanism.
“Sand dunes are designed to withstand storms,” says Hailey Paynter, an ecologist with Parks Canada, the federal agency responsible for managing the national park. “They simply need time and space to regrow.”
Thankfully, in the 12 months since Hurricane Fiona, signs of recovery have emerged in the Greenwich Dunes. Vegetation is sprouting on the ridges closest to the ocean. Over the next few years, the dunes will gradually grow as blowing sand accumulates around the plants.
The speed of dune recovery depends on the availability of sand to replenish them. This isn’t problematic on Greenwich Beach, given the abundance of sand, but it presents challenges in other areas. “You need a relatively wide beach and dry sand,” explains Danika van Proosdij, a coastal geomorphologist at Saint Mary’s University in Nova Scotia. Dunes on narrower or frequently submerged beaches will take longer to rebuild.
Over time, wind naturally shifts the position of sand dunes, and major storms can gradually push sand from the ocean-facing side over the top, causing dunes to move inland like a conveyor belt. Repeated erosion from more frequent and intense hurricanes could result in so much sand being transported that dunes would reform in new locations.
However, if we want dunes to protect vital areas such as neighborhoods, there may come a time when human intervention becomes necessary to keep the sand in place, says van Proosdij. In some areas, people are already fortifying vulnerable dunes by bringing in beach sand, reinforcing the mounds with trees, logs, and other biodegradable materials that slow down sand movement, or planting vegetation on top.
Ollerhead emphasizes that natural recovery may be slow, but nature’s ability to engineer dunes surpasses that of humans. “You can’t beat nature,” he states. “You have to learn to work with it.” The public can contribute by refraining from disturbing dunes. Despite their resilience during storms, dunes are delicate: Marram grass, one of the most crucial plants for stabilizing dunes, can be fatally trampled with as few as 10 footsteps. Parks Canada has roped off particularly fragile areas and placed signage to educate visitors on Prince Edward Island. “We want dunes to be as resilient as possible before a storm strikes,” Paynter affirms.
Fortunately, the Greenwich Dunes have ample space to shift and regenerate with storms, thanks to the protection provided by the national park. Beyond the park boundaries, Prince Edward Island has currently halted all coastal development as it devises a long-term policy to safeguard shoreline ecosystems.
Predicting how long it will take for the Greenwich Dunes to regain their former size is challenging, according to Ollerhead. However, amid the onslaught of more severe hurricanes in Atlantic Canada, the outlook for dunes remains largely positive, as long as they are cared for. “Most of the dunes will recover,” he concludes. “We just need to manage them in a way that allows them to respond to nature.”
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