Explore an underwater kelp paradise in this 360-degree video

In November of 2019, tucked inside the archives of the University of Victoria in British Columbia, marine ecologist Brian Timmer sifted through yellowing field notes, smudged penciled margins, and weather-worn survey logs that uncovered what he would later call a scientific treasure trove—forgotten records that would redefine what scientists knew about a changing coast.

These boxes of aerial photographs, hand-drawn maps, and scuba survey records documented the kelp forests of the northern Salish Sea in 1972. The materials offered something marine scientists rarely have: a detailed snapshot of an underwater ecosystem that existed half a century ago.

Using these 50-year-old records, Timmer, who is also a National Geographic Explorer, worked with his colleagues to reconstruct what bull kelp forests looked like in the 1970s. Then, just over fifty years later in 2023, they returned to the same waters.

Their findings, published in the journal Ecological Applications, showed that expansive underwater forests disappeared decades ago with little notice or public documentation.

In the early 1970s, the study area contained roughly 1,300 acres of bull kelp forest—nearly twice the size of New York City’s Central Park. Today, it contains none.

“Climate change has been impacting kelp forests decades before we thought,” Timmer says. “We have historical climate indicators like tree rings and shells that tell us about past temperatures, but it’s incredibly rare to have detailed records of what was happening underneath the ocean at the same time.”

In this case, he says, the historical data show the true magnitude of loss and provide a rare “smoking gun” linking long-term ocean warming to the disappearance of kelp forests.

Retracing steps

After combing through these newfound archives, Timmer and his team repeated the scuba surveys documented in old reports. He worked with the Hakai Institute, an independent coastal research group, to fly identical  flight lines used in the 1972 aerial photos to capture modern images of the coastline. Nearby lighthouse records also provided a log of daily ocean temperatures taken by hand since 1915, and were compared with global warming trend data from NOAA, which dates back to the 1880s.

Satellite imagery dating back to 1984 already showed no detectable kelp canopy in areas Timmer and his team were studying. The culprit appeared to have been a large shift in Pacific Ocean climate during the late 1970s, when regional waters warmed dramatically.

“The northern Salish Sea is a global hotspot for ocean warming,” Timmer says. “Temperatures there have increased faster than about 90 percent of the world’s oceans.”

Small pockets of kelp may have persisted in cooler refuges—such as near the southern tip of Denman Island, which rests just off the eastern flank of Vancouver Island, separated by a narrow channel in the Salish Sea—but they were sparse enough to escape satellite detection.

In 2015 a massive marine heatwave along the West Coast, which scientists dubbed ‘The Blob,’ was the final blow to remaining kelp forests that had  been hanging by threads for decades.

“The scale of decline that can happen within a human lifetime—and effectively go unnoticed—is really striking,” says kelp ecologist Sam Starko of Curtin University in Australia, who was not involved in the research.

“Forests that fifty years ago covered several hundred hectares are now essentially gone,” Starko says. “And the timing matters, because we often think of modern marine heatwaves as a recent driver of kelp decline. But this shows the climate change process has been underway for decades.”

How marine life is changing

Across the Pacific coast, kelp forests are essential nurseries and feeding grounds for species such as—from orcas, to sea otters, and to abalone. In the Salish Sea, kelp forests are a habitat for lucrative species that define the region, including herring, salmon, and rockfish, and sea stars. 

In warmer regions, ocean warming often leads to “tropicalization,” where warm-water species expand into new areas. But the Salish Sea sits far from the tropics. Instead, Timmer and Starko are among a broader research consensus that the region may be experiencing ecological retreat—with cold-water species disappearing and fewer replacements moving in.

That kind of ecological retreat doesn’t just thin out cold-water species—it unravels the kelp-anchored food web itself, eroding critical migration corridors for Pacific salmon and stripping away nursery and feeding grounds that sustain everything from zooplankton to herring to rockfish.

Timmer, who is Stó:lō from the Chawathil First Nation on his father’s side, says that the kelp forests documented as lost in this study once helped sustain the salmon that, for thousands of years, nourished his ancestors along the Fraser River—the largest river entering the Salish Sea.

Replanting the forests of the sea

As a scuba instructor on Vancouver Island, Timmer’s favorite pastime was sitting quietly along the seafloor of the Salish Sea and looking up through the distorted sunlight, observing the towering columns of bull kelp drifting above him.

“I watched firsthand as all of the kelp forests at all of my favorite dive sites disappeared within a single year,” Timmer says.

That’s why, in addition to his research, Timmer is working with other scientists and First Nations organizations like Nanwakolas Council and the We Wai Kai First Nation, in an effort to restore bull kelp along parts of the Pacific coast.

The effort spans a broader coalition of First Nations and Indigenous partners working to restore these ecosystems.

“Kelp forests used to be incredibly abundant,” says Connie Crocker (Crocker’s native name is Xqulsiim), a First Nations liaison for the Kelp Rescue Initiative and member of the Penelakut Tribe. “I completely took for granted how wonderful and plentiful it was in the early 1970s,” she says. “Underneath the kelp was the richest area biologically. It’s where all of the fish were living, and we realize now how much it supported everything else.”

As kelp forests disappeared, she says, communities that once fished herring among their fronds and wove with kelp lost not only a source of food, but a thread of cultural continuity.

For the Penelakut Tribe, whose reserve is on a small island in the Salish Sea, the disappearance of kelp forests has also meant losing the lifestyle they once supported, Crocker says. Many families in the community still rely on nearby coastal waters for food, but without the underwater forests, those resources have become harder to find.

“People that live on reserves face poverty, and resources are limited,” says Crocker.

Timmer and his partners have begun replanting thousands of square feet of kelp  to rebuild underwater forests that disappeared decades ago. And while restoration alone cannot stop ocean warming, scientists note that it may help strengthen coastal ecosystems enough to help them survive until or if warming abates.

“Kelp is just magical in its ability to improve the ocean,” Crocker says. “I think restoring kelp may be that magic ingredient in helping to right some of the wrongs we’ve done to our seas.”