The Southern California coastline is home to iconic kelp forests that lie just beneath the surface. Kelp forests are one of the most productive ecosystems on the planet, found along 30% of the world's coastline. A recently published study from Scripps Institution of Oceanography spanning 40 years of observations gives us the most detailed picture yet of how these forests are changing, and what that means for the coast we love.
WHAT: What are kelp forests, and why do they matter?
Kelp refers to a group of large, photosynthetic brown algae that anchor themselves on the rocky ocean floor and grow toward the sunlight at the surface. Giant kelp (Macrocystis pyrifera), the primary forest-building species off the Southern California coast, can grow to over 100 feet tall and live up to 10 years. When kelp individuals grow together in dense aggregations, they form what we call a kelp forest. Unlike plants, kelp is an algae — an ecosystem engineer whose size and productivity set it apart from other seaweeds.
Giant kelp forest off of Catalina Island, CA. Photo by Oriana Poindexter.
If you've surfed along the Southern California coast, especially pre-2014, you've probably experienced the benefits of the kelp forests without realizing it. A dense kelp canopy at the surface acts as a natural windbreak, smoothing out wind chop and glassing off the surface inshore of the kelp beds. This is one of the reasons our favorite reef breaks can hold clean conditions even on breezy days. If you paddle or ride your board through the canopy of a healthy kelp bed, you might find your fin gets caught on the stipes, jerking your board to a stop. That interaction, annoying as it can be, is actually a sign of a thriving ecosystem.
Kelp at the surf break near Santa Barbra, CA. Photo Cara Bram.
Kelp forests are like underwater cathedrals. The stands of kelp reach from the seafloor to the surface, forming the complex habitat that hundreds of species need to survive. Fish live among the fronds, invertebrates like abalone, sea stars, and urchins live along the bottom, and the young of open-ocean species hide out in the canopy before taking off for the great wide open.
When storms rip kelp loose, they end up floating as 'kelp paddies', beloved by fishermen for aggregating fish out at sea, or piled up on shore as 'wrack', annoying beachgoers but benefiting seabirds and becoming an important part of the food web. Kelp forests do a lot of work out of sight, including physically protecting coastlines from storm surges and drawing down carbon as the kelp grows (up to 2 feet per day in ideal conditions).
WHY: Are Southern California's kelp forests changing, and why should we care?
The size and density of the kelp forests off our coast have historically ebbed and flowed in cycles. El Niño storms can tear entire stands off the seafloor, and warm surface waters can destroy the canopy of the kelp. Normally, the water at the ocean's surface can be up to 10 degrees Fahrenheit warmer than the water at the bottom, a phenomenon known as the thermocline. Kelp has a complex life cycle, but it keeps its reproductive parts in the colder water at the base of the organism. Specialized leaves, called sporophylls release microscopic spores into the water, which reproduce and repopulate kelp.
Giant kelp forest in La Jolla, CA. Photo: Oriana Poindexter.
In 2014 and 2015, a mass of unusually warm water, nicknamed 'The Blob', appeared in the eastern Pacific and never fully left. Since then, water temperature in the kelp forests has not dropped below 57°F, a threshold the kelp needs to thrive. The 2026 Scripps study, the longest of its kind in existence, found that giant kelp individuals in this area now live shorter lives and can struggle to reproduce before they die.
Warmer water brings other pressures. Parasitic bryozoans cluster on fronds and weigh them down, pulling them away from the sunlight they need. Native species of sea urchins can proliferate and overgraze. Warmer water also strips away the nutrients like nitrogen that kelp depends on. Other species more adaptable to warm water can move in and take over the reef area, preventing baby kelp from finding a foothold. “Climate change is the principal driving factor, but understory competition is a major proximal cause,” said study co-author Paul Dayton.
I started surfing Swamis in 2013, and I remember it being totally normal to get your fin stuck in kelp, sometimes throwing me off my longboard on the best wave I'd caught that day. That hasn't happened to me since the 2014/2015 marine heatwave. The kelp beds have recovered somewhat further offshore since then, but they haven't come back to the point where they're interacting with the surf line the way they used to. If you've been surfing Southern California long enough, you may have already noticed this.
Surfing with kelp. Photo Cara Bram.
This pattern isn't unique to our coast. In Northern California and Southern Australia, marine heatwaves in the 2010s triggered cascades that led to the loss of over 90% of kelp canopy cover in each region in less than a decade. Southern California's story is its own, but it's part of a broader shift in how these ecosystems are faring under warming conditions.
ACTION: Steps we can all take - and talk about.
The story is nuanced - ecosystems adapt, and giant kelp or other species may shift northward in search of cooler waters.
“In ecology, even though we have the longest time series record of giant kelp in existence, it’s still a tiny snapshot. A human lifetime is a blink of an eye,” said Kristin Riser, another of the study’s co-authors.
Long-term observation is itself a form of stewardship, and the 40-year Scripps dataset exists because people showed up, season after season, and paid attention.
Here are some ways to do the same:
1. Support scientists, research organizations, and artists!
Researchers at Scripps and other academic institutions are doing the long-term work that makes informed decision making possible. Organizations like the Kelp Forest Alliance and Reef Check help people connect with researchers and get involved in long-term monitoring efforts in their regions. Artists can translate that science into different forms in order to reach audiences far beyond the research community, through museum and aquarium exhibits, public installations, and other spaces where people encounter these ideas outside of a scientific context. Follow the work, share it, and if you're able, support it. (Seea suggest following Oriana Poindexter! She does incredible photographic work exploring kelp forests)
Oriana Poindexter's cyanotypes hanging at the Catalina Museum of Art and History. Photo by Heidi Zumbrun.
2. Reduce what you can.
Rising ocean temperatures are the principal driver of the changes we're seeing. Individual actions matter less as standalone gestures than as part of a broader cultural shift toward taking this seriously.
3. Put your face in the water — and talk about it!
Most people who love the Southern California coast, and even many lifelong surfers, have never put their face in the water to see what's beneath the surface. Our kelp forests are accessible to any strong swimmer, snorkeler or diver. You don't need to be a scientist to observe what is out there, or what is changing. You just need a mask, wetsuit, and fins to start learning. That's where the conversation starts.
Naomi Folta, a surfer, free diving with kelp. Photo Megan Young Blood.
I'm (Oriana Poindexter) a photographic artist and marine scientist — I grew up in Laguna Beach and have been swimming, surfing, and diving regularly in the kelp forests of San Diego, Orange County, and Catalina Island for over 15 years. I earned a Masters degree in Marine Biodiversity & Conservation from Scripps Institution of Oceanography, the same institution behind the 40-year study referenced here. Today, I create artwork with kelp and seaweed specimens collected from my dives, making unique, life-size records of the organisms themselves. The collections of specimens I gather from specific places over time combine into a portrait of those places, which I then share with the public through exhibits and installations. You can see my current show, The Blue Forest, at the Catalina Museum for Art & History in Avalon, CA through October 2026. It's my way of paying attention, and of inviting others to do the same.
Oriana working with kelp before creating a cyanotype. Photo Heidi Zumbrun.
As keystone species and pillars of marine ecosystems, kelp forests are vital. They provide a crucial lens for scientists into the complex and symbiotic nature of the ocean. Let's continue to support, explore, and learn from this extraordinary algae!
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