The Valley That Feeds a Nation

How tectonics, sediment, and water created one of the most productive landscapes on Earth.

Aerial view of California’s Central Valley, where Interstate 5 slices through a vast patchwork of irrigated fields, some of the most productive farmland on Earth, shaped by deep alluvial soils and Sierra Nevada snowmelt. (Photo: Erik Olsen)

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I love California’s bizarre, complicated geology. For many years, I had a wonderful raised-relief map of the state on my wall made by Hubbard Scientific (it hangs on my son’s bedroom wall today). On the map, color and molded plastic contours reveal the state’s diverse and often startling geological formations. I loved staring at it, touching it, imagining how those landscapes came to be over geologic time.

There is so much going on here geologically compared to almost any other state that geologists often describe California as one of the best natural laboratories on Earth, a place so rich and varied that entire careers have been built trying to understand how all its pieces fit together. As the U.S. Geological Survey (USGS) puts it, nearly every major force that shapes the Earth’s crust is visible here, from plate collision and volcanism to basin formation and mountain uplift. Some of my favorite writers, like John McPhee, have described California as a collage of geological fragments, assembled piece by piece over deep time, in a way that more closely resembles an entire continent than a single region.

But when we think about California’s geology, most of us probably imagine the Sierra Nevada’s towering granite peaks, the pent-up force of the San Andreas Fault, or the fact that Lassen Peak is still an active volcano. Those places grab our attention. Yet when it comes to a geological feature that has quietly shaped daily life in California more than almost any other, we should consider the Central Valley, arguably the state’s most important geological masterpiece.

Topographical and irrigation map of the Great Central Valley of California: embracing the Sacramento, San Joaquin, Tulare and Kern Valleys and the bordering foothills (Source: NYPL Digital Collection)

Sure, the valley is flat as a tabletop, stretching out for mile after mile as you drive Interstate 5 or Highway 99 (one of my favorites), but once you consider how it formed and what lies beneath the surface, the Central Valley reveals itself as a truly remarkable place on the planet, another superlative in our state, which, of course, is already full of them.

The Central Valley was formed when tectonic forces lowered a broad swath of California’s crust between the rising Sierra Nevada to the east and the Coast Ranges to the west, creating a long, subsiding basin that slowly filled with sediment eroded from those mountains over millions of years. For thousands of years, the southern end of the valley was dominated by Lake Tulare, a mega-freshwater lake that was once the largest freshwater lake west of the Mississippi. You might remember that just a few years ago, Lake Tulare briefly reappeared after a series of powerful atmospheric river storms. I went up there and flew my drone because I was working on a story about the construction of California’s long-troubled high-speed rail, which had halted construction because of the new old lake.

Lake Tulare reemerges in the southern San Joaquin Valley after powerful winter storms, flooding roads and farmland and briefly restoring the historic inland lake that once dominated this basin. (Photo: Erik Olsen)

On the other side in the west, the Coast Ranges rise up, hemming in the valley and basically holding it in place, forming something like a gigantic, hundreds-of-miles-long bathtub. One popular Instagrammer commented that it looks as if someone used a huge ice cream scoop to dig out the valley. As the surrounding mountains continued to rise, rain, snowmelt, and wind carried untold tons of silt and sediment downslope, steadily depositing them into this enormous basin over millions of years.

This process created what geologists call the Great Valley Sequence, a staggering accumulation of sedimentary material that, in some western portions of the basin, reaches a depth of 20,000 meters, or approximately 66,000 feet. Ten MILES.

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This long, slow process produced what geologists call the Great Valley Sequence, an immense stack of sedimentary rock built up over tens of millions of years as the basin steadily subsided and filled. In some western portions of the valley, that accumulated package reaches a depth of 20,000 meters in thickness, about 66,000 feet, or close to ten miles of layered geological history lying beneath the surface. That’s kind of mind-blowing.

Endless rows of pistachio orchards stretch across the Central Valley at dusk, a geometric testament to the deep soils and engineered water systems that have turned this ancient basin into one of the world’s great agricultural landscapes. (Photo: Erik Olsen)

It’s not just “dirt”; it’s a ridiculously deep, nutrient-rich record of California’s geologic history. There are the remains of trillions of diatoms, or microscopic plankton, whose organic remains were crushed into oil shales that are home to significant petroleum deposits. During the late Pleistocene and into the Holocene, the southern end of the valley was dominated by Lake Tulare, mentioned above, a vast freshwater lake that in wet periods spread across 600 to 800 square miles, making it the largest freshwater lake west of the Mississippi. As the water evaporated and drained, the valley floor became exceptionally flat, similar to what we see today.

Most valleys are narrow corridors carved by a single river, but the Central Valley is a vast, enclosed catchment shaped by many rivers, trapping minerals and sediments from surrounding mountains rather than letting them wash quickly out to sea. This mix created near-ideal conditions for agriculture. For the uninitiated, the Central Valley is typically divided into two major sections: the northern third, known as the Sacramento Valley, and the southern two-thirds, known as the San Joaquin Valley. That lower region can be further broken down into the San Joaquin Basin to the north and the Tulare Basin to the south.

Relief map of California showing the Central Valley standing out as a wide, uninterrupted green swath between the rugged Sierra Nevada and the Coast Ranges, its flat, low-lying basin sharply contrasting with the surrounding mountains that frame and define it.

Today, because of all that fertility, the Central Valley is one of the world’s most productive agricultural regions, growing over 230 different crops. It produces roughly a quarter of the nation’s food by value, supplies about 40 percent of U.S. fruits, nuts, and vegetables, and dominates global markets for crops like almonds, pistachios, strawberries, tomatoes, and table grapes. Truly a global breadbasket.

Of course, none of this would have been possible without water. The real turning point in California’s story was learning how to capture it, move it, and store it. From mountain snowpack to canals and reservoirs, controlling water has been the quiet engine behind much of the state’s success. When human engineering intervened in the 20th century through the Central Valley Project and the State Water Project, it essentially redirected a geological process that was already in place, replacing seasonal floods and ancient lakes with a controlled system of dams and canals.

Roadside cutout farmer holding bright green heads of lettuce at the edge of a Central Valley field, a playful nod to the region’s identity as one of the most productive agricultural landscapes in the world. (Photo: Erik Olsen)

Alas, this productivity is not without geological limits, and we’ve done a pretty good job over-exploiting the valley’s resources, particularly groundwater, to achieve these things. The same porous sediments that store our life-giving groundwater are susceptible to compaction. In parts of the San Joaquin Valley, excessive pumping has caused the land to subside, sinking by as much as 28 feet in some locations, causing the soil to crack and the landscape to physically lower as the water is withdrawn. How we deal with that is a whole other story. Recent storms have helped California’s water supply tremendously, but the state seems destined to remain in a permanently precarious state of drought.

But when you talk geology, you talk deep time. You talk about eons and erosion, mountain ranges that rise and are slowly worn down, sometimes leaving behind something as breathtaking as the granite domes of Yosemite.Against that scale, the Central Valley can seem almost plain, but as I hope I’ve made the case here, when you look a little closer at even the most mundane things, you realize there is magnificence there, and few places on this planet are as magnificent as the state of California.

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Measuring the Earth’s Tremors and the Development of the Richter Scale

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Seismometer measuring earthquake impact.

We all know California is known for earthquakes. AND most people probably know there’s a reason for that: California lies along the Pacific Ring of Fire, and it also sits at the boundary between the Pacific and North American tectonic plates, creating the San Andreas Fault and making it especially prone to seismic shaking. Even if you’ve lived here for just a short while, the chances are you’ve felt a tremble or two.

Of course, the biggest earthquake most people are aware of in California was the 1906 earthquake in San Francisco, which shook the city hard and led to a massive, all-consuming fire that together destroyed more than 28,000 buildings, killed an estimated 3,000 people, left roughly a quarter million residents homeless, and reshaped the city’s development and building practices for decades afterward. (Here’s a story about one particularly important building). One of my favorite books on the subject is Simon Winchester’s Crack at the Edge of the World, which is filled with wonderful facts and stories about California’s precarious geology and what happened that day in San Francisco.

More recent events continue to underscore the ever-present threat of significant temblors. In December 2024, a 7.0-magnitude earthquake struck off the coast near Eureka, prompting tsunami warnings and evacuations. More recently, in March 2025, the Bay Area experienced a series of minor tremors along the Hayward Fault. While these quakes caused minimal damage, there is always the looming threat of ‘The Big One’, a potentially catastrophic earthquake expected along the San Andreas Fault, well, any day now . Scientists warn that the southern section, overdue for a major rupture, could trigger widespread destruction, with estimates suggesting a magnitude 7.8 event could result in “significant casualties and economic losses”.

Damage to Interstate 880 in Oakland, CA, after it collapsed during the Loma Prieta earthquake In October 1989.
(Photo: Paul Sakuma/AP)

But what about that number, 7.8? Where does it actually come from, and what does it mean?

When we talk about measuring earthquakes: their size, their energy, their destructive potential, most of us still instinctively think of the Richter scale. It’s now shorthand for seismic strength, although, ironically, scientists today rely on other, more modern magnitude systems. We’ll get to that shortly. But the Richter scale remains one of the most influential ideas in the history of earthquake science.

The story of how it came to exist starts in a lab at a world-renowned scientific institution in Pasadena: the California Institute of Technology (CalTech). It begins with a physicist named Charles Richter.

In 1935, working with German-born seismologist Beno Gutenberg, Richter laid the groundwork for modern earthquake study and quantification. Their breakthrough work helped transform vague and subjective observations into precise, quantifiable data. Scientists could now better assess seismic risk and ultimately help protect lives and infrastructure. So the effort not only changed how we understand earthquakes, it laid the foundation for future advances in seismic prediction and preparedness.

Charles Richter studies a seismograph log that records the earth’s movements.
(Credit: Wikipedia and Gil Cooper, Los Angeles Times)

At the time, existing intensity-based earthquake measurements relied on subjective observations and the so-called the Mercalli Intensity Scale. That means that an earthquake’s severity was determined by visible damage and how people felt them. So, for example, a small earthquake near a city might appear “stronger” than a larger earthquake in a remote area simply because it was felt by more people and caused more visible damage. For example, the 1857 Fort Tejon earthquake, estimated around magnitude 7.9, ruptured hundreds of miles of the San Andreas Fault, but because it struck a sparsely populated stretch of desert and ranch land, it caused relatively little recorded damage and few deaths.

Like any good scientist, Richter wanted to create a precise, instrumental method to measure earthquake magnitude. He and Gutenberg designed the Richter scale by studying seismic wave amplitudes recorded on Wood-Anderson torsion seismometers, an instrument developed in the 1920s to detect horizontal ground movement. Using a base-10 logarithmic function, they developed a system where each whole number increase represented a tenfold increase in amplitude and roughly 31 times more energy release. This allowed them to compress a wide range of earthquake sizes into a manageable, readable scale. So, for example, a magnitude 6 quake shakes the ground 10× more than a magnitude 5. Also, a magnitude 7 quake releases about 1,000× more energy than a magnitude 5 (i.e. 31.6 × 31.6 ≈ 1,000).

How the Richter Magnitude Scale of Earthquakes is determined from a seismograph. (Credit: Benjamin J. Burger)

The innovation allowed scientists to compare earthquakes across different locations and time periods, significantly improving seismic measurement and research.

Once the Richter scale came into being, it not only changed how scientists described earthquakes, it changed how we all thought about them. Earthquakes were no longer defined only by damage or casualties, but by a single, authoritative number. And so by the 1960s and 1970s, “the Richter scale” had become standard language in news reports and scientific writing. Even today, long after researchers have moved to newer magnitude systems, you still occasionally see it in news reports.

Probabilistic Seismic Hazard Map (https://databasin.org)

The Richter Scale, and Richter himself, became so well known on campus, that one of Caltech’s great comic writers and performers, J. Kent Clark, actually wrote a song about them:

“When the first shock hit the seismo, everything worked fine. It measured:

One, two, on the Richter scale, a shabby little shiver.

One, two, on the Richter scale, a queasy little quiver.

Waves brushed the seismograph as if a fly had flicked her.

One, two, on the Richter scale, it hardly woke up Richter.”

Alas, Richter, according to Clark, was so “morbidly shy” that he never showed up to any of the performances. At first, he didn’t like the song, reportedly calling it an “insult to science”, but later in life he came to appreciate its good humor. There’s a YouTube reading of the song here.

Unfortunately for Richter, over time it became clear that the Richter scale had a fundamental flaw: it couldn’t measure the largest earthquakes accurately. Because it relies on seismic wave amplitude, very powerful quakes tend to “saturate” on the scale, making different events appear similar in size.

Since the 70s scientists have come up with another way to measure earthquakes called the Moment Magnitude Scale. Developed by Hiroo Kanamori and Thomas Hanks the Moment Magnitude Scale calculates how much energy an earthquake actually releases by examining the size of the fault that slipped, how far it moved, and the physical properties of the surrounding rock. The method works reliably for both small tremors and the planet’s largest earthquakes, which the original Richter scale struggled to do.

A striking view of the Palmdale roadcut, showcasing layers of exposed rock that tell the geological story of Southern California. Located just a short distance from the San Andreas Fault, this site provides a vivid snapshot of tectonic activity, where Earth’s shifting plates have shaped the landscape dramatically over millions of years. (Credit: Erik Olsen)

Of course, neither the Richter scale nor the Moment Magnitude Scale have done much to help us actually predict earthquakes. That remains an elusive dream. That said, ShakeAlert, the state’s early-warning system, doesn’t predict quakes, but it can detect them as they begin and send alerts before the worst shaking arrives. Those seconds can be enough to drop to the ground, slow trains, or shut down sensitive systems. The system has also had misfires and missed alerts, so we’re not there yet.

Dr. Lucy Jones, who helped champion early earthquake warning in California, has said that ShakeAlert usually works exactly as intended. It is “tuned” to avoid sending alerts for minor shaking, because otherwise people would be getting notifications all the time, creating a kind of Chicken Little problem where warnings start to lose their impact.

According to experts involved with the system, ShakeAlert is designed to send alerts for earthquakes in L.A. County with a magnitude of at least 5.0, or for quakes anywhere that are strong enough to produce “light” shaking in the Los Angeles area. But according to news reports, that sometimes leaves people feeling disappointed or confused. During the 2019 Ridgecrest quakes, for example, Los Angeles didn’t receive a public alert because the shaking there was below the warning threshold, although many people felt it. Jones has said the real challenge isn’t just the technology, but making sure alerts are communicated in a way people understand and trust.

If there is ever a “Big One,” and scientists say it’s a matter of time, we can only hope we’ll get even a small amount of early notice.

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Ancient and Poisonous Cycads Are the Prehistoric Plants of Southern California

Cycad at Descanso Gardens in La Canada Flintridge. (Photo: Erik Olsen)

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If there’s one thing our increasingly digital world has pushed me toward, it’s a desire to reconnect with the natural one. At a moment when AI, deepfakes, and synthetic media blur the line between real and artificial, I find myself drawn more strongly to things that are undeniably, stubbornly real. So I spend a lot of time turning away from screens and paying closer attention to the world around me, searching for things in nature that are touchable, tangible, and timeless.

It turns out California is full of those opportunities, and I want to call your attention to just one: a plant.

Thermal image of a male cone of the cycad Zamia furfuracea during pollen release. (Photo by Wendy Valencia-Montoya)

The New York Times ran a fascinating piece recently about a type of plant that is both ancient and highly unusual, and one that I suspect most people know very little about: cycads. Many cycads resemble palm trees at first glance, but that’s misleading. Cycads are only distantly related to palms, belonging instead to one of the oldest surviving lineages of seed plants on Earth, the gymnosperms. Palms, by contrast, are angiosperms, or flowering plants, making them evolutionary newcomers compared to cycads, which were already thriving long before flowers existed at all. In fact, cycads and palms diverged from a common ancestor approximately 300 to 350 million years ago. Their apparent similarity in form is not a sign of close kinship but a classic case of convergent evolution, in which unrelated organisms independently arrived at a similar form because of adaptation in similar environments.

Cycad cone (Dioon edule) at Descanso Gardens. Built for an ancient world: Cycad cones are among the largest and oldest seed structures on Earth, evolving long before the first flower bloomed. Their rugged design helped cycads thrive alongside dinosaurs — and survive into the modern day. (Erik Olsen)

I have always found cycads really cool, in part because they are some of the closest living things we have to connect us to the era of the dinosaurs, and because they just look — and feel — incredibly bizarre compared to most other plants. And the Times piece made clear that we are still actively learning how they work, which I find fascinating.

The Times piece explains that cycads attract insect pollinators not through color or flowers, but by heating their cones at dusk and emitting infrared radiation. The process is known as thermogenesis and its rare in plants. (It turns out the female Skunk Cabbage, for example, warms up to melt away snow in the winter.) Specialized beetles, equipped with infrared-sensing antennae, detect this warmth and are guided from male cones to female cones (more on this in a sec) in a precisely timed sequence that ensures pollination. The relationship is so ancient, stretching back hundreds of millions of years, that some researchers now suspect heat-based signaling may lie at the very foundation of pollination, long before flowers evolved petals, color, and scent. However, this is controversial.

A *Zamia* cycad, one of roughly 66 cycad species growing at Descanso Gardens. (Photo: Erik Olsen)

Fascinating, right? That’s just the beginning.

My interest in cycads grew out of the many visits I have made to two major botanical gardens in Southern California that I return to again and again: Descanso Gardens and the Huntington. While The Huntington features a world-renowned, massive scientific collection of over 1,500 plants sprawling across a specialized hillside Cycad Walk, Descanso Gardens offers a boutique, immersive “Ancient Forest” experience that replicates a prehistoric Jurassic environment beneath a canopy of redwoods. Both are really excellent to walk through. And these collections, unlike most museum encounters you might encounter with ancient life (i.e. dinosaur bones), consist of live plants you can actually walk among and touch.

Cycad leaves are thick and very rigid, much different from most other plants. (Photo: Erik Olsen)

One of the most remarkable features of cycads is the toughness of their leaves. They are much stiffer and heavier than other plants. Almost plastic and fake. It turns out cycads invest in a thick, waxy cuticle that has some key benefits: it reduces water loss, reflects harsh sunlight, and protects them against insects and grazing animals. In other words, they are both survivors and a difficult meal, offering a key evolutionary advantage during a time when giant plant-eating dinosaurs roamed the Earth.

(That said, there is evidence that some dinosaurs actually did feed on cycads. There are telltale signs of cycad cellular material in dinosaur coprolites, or fossilized poop, but scientists don’t think it was common.)

And then there are the cones.

A cycad in full cone, displaying one of the largest and most unusual reproductive structures in the plant world. These massive cones can weigh many pounds, grow for months or even years, and play an active role in pollination, sometimes heating up and releasing strong odors to attract specialized insects. (Photo: Erik Olsen)

Cycad cones are among the strangest reproductive structures in the plant world. They are often massive, sometimes weighing many pounds, tightly packed, and so symmetrical they look almost engineered, as if they were 3D printed. They are also unusual because each individual cycad plant is strictly male or female, a condition known as dioecy. A male cycad will only ever produce pollen-bearing cones, while a female will only produce seed-bearing cones. Pines and firs, which are also gymnosperms, typically produce both male and female cones on the same plant. Cycads do not. There is no overlap between the sexes, no ability to self-fertilize, and no natural fallback mechanism if a partner is missing. (Cycads can be “bred” using off-shoots or pups, which is how many of the plants in these gardens came to be.)

That odd rigidity is on display at The Huntington in San Marino, which has one of the earth’s few specimens of Encephalartos woodii, often called “the loneliest plant in the world”. Only a single wild male was ever found, in South Africa in the late 1800s, and no female has ever been discovered (although scientists are using drones and AI to find one). There are a few other specimens alive today outside the Huntington, but they are all clones propagated from that one original plant. There’s a great Instagram from the Huntington on this.

Male cones of *Encephalartos woodii* at the Huntington (Photo: The Huntington)

So, the male cycad cones produce pollen and the female cycads make seeds. In several species of cycad, those seeds are big and glossy and plump and bright red or orange. They look temptingly like fruit, although remember that true fruits didn’t evolve until much later, with flowering plants. They do have a fleshy outer layer called a sarcotesta that looks and feels fruit-like, but it’s not. That’s weird.

In another bizarre twist, those seeds are loaded with potent toxins that are very dangerous to animals, including humans. They can damage the liver and the nervous system, and even kill. (So even though I urged you to touch the leaves, maybe don’t handle the seeds…or at least wash your hands afterwards, and certainly don’t try to cook and eat them.)

Cycad with large cone at Descanso Gardens in La Canada Flintridge. (Photo: Erik Olsen)

Why make a seed dressed in bright, attractive colors if it’s toxic? That question has long puzzled scientists. Bright colors usually signal an edible reward, but in cycads the fleshy outer layer of the seed, the sarcotesta, is not toxic and does contain nutrients. The toxins are concentrated deeper inside the seed, suggesting the sarcotesta may have served as a non-fruit mechanism for seed dispersal, encouraging animals to handle or partially consume the seed while the embryo itself remained protected.

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Cycads are not indigenous to California. In nature, they are found almost entirely in tropical and subtropical regions, growing in parts of Africa, Australia, Asia, and the Americas, often in warm, stable landscapes that long predate California’s modern climate. That said, Southern California turns out to be an unusually good place to grow cycads. We have mild winters, dry summers, and a long growing season, which mimic the conditions in which cycads evolved across Africa, Australia, and parts of the Americas. That made the region attractive to collectors early on in the 20th century, when botanical gardens were expanding their missions from display to preservation.

“We are in a actually in a biodiversity hot spot here in California,” Sean C. Lahmeyer Associate Director, Botanical Collections, Conservation and Research at the Huntington told me. “Because of our climate in California we’re able to grow so many different types of plants. If you were to compare this garden to, say, one in England or at Kew, they have to grow things inside of greenhouses.”

A cycad in the genus *Dioon*, an ancient seed plant often mistaken for a palm. Its stiff, feather-like leaves and armored trunk reflect a lineage that dates back more than 250 million years, long before flowers. (Photo: Erik Olsen)

At The Huntington, cycads arrived largely through early plant collecting and exchange. Henry Huntington’s gardeners were building a world-class botanical collection at the same time as explorers and botanists were (controversially) bringing rare plants back from around the globe. Over decades, the Huntington expanded its cycad holdings, recognizing both their horticultural appeal and their scientific importance. Today, it houses one of the most significant cycad collections anywhere, including that famous Encephalartos woodii.

Descanso Gardens’ story, meanwhile, is more personal and more recent. In 2014, local residents in La Canada Flintridge, Katia and Frederick Elsea donated their private cycad collection, more than 180 plants representing dozens of species, to the garden. Many were rare, endangered, or extinct in the wild. Descanso said yes, of course, and built the Ancient Forest around them, and suddenly one of the most important cycad collections in the country was open to the public in La Cañada Flintridge.

A mature cycad, its trunk layered with old leaf bases and topped by a crown of stiff, palm-like fronds. (Photo: Erik Olsen)

Cycads are not all rare. You may even notice certain common specimens growing in people’s yards around California. But precisely because they are so ancient and so different from most plants we’re used to, I’d urge you to see them in person at places like Descanso Gardens and The Huntington. Touch the leaves. Study the symmetry. Marvel at the massive cones. (Just don’t put anything in your mouth.) Take a moment to consider just how unusual these plants are. And if you feel the need to pull out your phone to learn more, go ahead, but then put it away and spend a little time with the plants themselves.

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California’s Two-Spot Octopus is the Alien Mind Off Shore

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I have a deep passion for octopuses. I have made several short documentaries about them and even traveled twice to Indonesia with one of the world’s leading octopus scientists to film them in their natural habitat. My home office is packed with octopus imagery and iconography, and years ago I made a personal vow never to eat octopus. Squid and other mollusks still get a pass in my book. If you want to debate the ethics of this, fine.

The octopus is a singularly unique creature in the animal kingdom. They are essentially related to clams and abalone and snails, yet they possess an intelligence (let alone a body form) that is so strange and alien, it is unsurprising that sci-fi movies like Arrival feature creatures that are both very intelligent and octopus-like. If you have ever spent an hour alone on the seafloor with an octopus (as I have….just looking eye to eye), you know that they are something different. While most other fish swim away, an octopus will often linger and even engage in what might be considered play.

In fact, we’ve learned that octopuses rely heavily on learning rather than instinct. Unlike many animals that follow hardwired behavioral scripts, octopuses explore, test, and improvise. For that reason and others, it’s hard not to think of them more like other familiar mammals, like a dog or a dolphin.

And then you consider evolution and it gets really weird.

The common octopus (Octopus vulgaris) in Indonesia. (Photo: Erik Olsen)

That’s the thing. When we talk about smart animals, we tend to think of vertebrates: dolphins, whales, dogs, horses, elephants. They all share a long evolutionary lineage with us, shaped by natural selection into social, communicative, problem-solving creatures whose minds we recognize because they work in ways familiar to our own. But octopuses are not like that. They diverged from our lineage hundreds of millions of years ago. The last common ancestor humans share with an octopus was a simple wormlike creature. From that fork in the tree of life, vertebrates developed one path toward cognition while invertebrates followed others, some of them evolving remarkable abilities (spiders anyone?!), but rarely what we traditionally call intelligence.

Somehow, the octopus broke that pattern. It built a mind through a completely different architecture, with neurons spread throughout its arms, distributed processing, and behaviors that suggest curiosity, play, memory, strategy. They’ve developed these complex behaviors because they are essentially large blobs of protein moving about the seafloor. When exposed, they are very vulnerable, and so millions of years of evolutionary pressure have compelled them to become, well, smart. What makes this even stranger is how short their lives are…usually just a year or two. All of that intelligence compressed into what, in the grand scheme of things, is just a brief flash of existence.

Seeing eye to eye with an octopus in Indonesia (Photo: Erik Olsen)

Alongside them, their closest cousins, the cuttlefish, have evolved similarly striking cognitive abilities, but they don’t quite equate with the octopus. Still, together they show that intelligence is not a single climb up one evolutionary ladder but something nature can shape in entirely different ways. Convergent evolution.

So, if you were searching for meaning and purpose and trying to understand the process of intelligence itself, you could hardly find a better creature to study than the octopus. Short of discovering another intelligent life form somewhere in the universe, the octopus is one of our best bets to grasp what intelligence is and how it evolves.

Scientists are doing precisely that right now. And there is one species they turn to the most: our own California two-spot octopus (Octopus bimaculoides), one of the most remarkable animals on the planet. (They get their name, obviously, from the attractive blue spots on their sides.) The California two-spot octopus spends its days tucked into small crevices and hunting right off our shores. You can see them up and down the coast. I have only encountered a few in the wild, but each time it’s special, like a Christmas gift.

California two-spot octopus in a lab (Photo: Erik Olsen)

What’s especially cool is that the California two-spot octopus has gone from a coastal curiosity — an animal long seen, admired, and loved by divers — to a full-fledged scientific model, teaching us new things about neuroscience, genomics, and behavior. In 2015, researchers published the first complete genome sequence of the California two-spot octopus, and it marked a watershed moment in the study of cognition. For the first time, scientists could look directly at the genetic architecture behind an intelligence built on an evolutionary branch completely separate from our own. The two-spot became the go-to organism for this work because it is abundant in local waters, manageable in laboratory settings, and displays a level of problem solving that can be tested and observed in controlled conditions. I guess they make great pets, too, because several folks on Instagram have them and make pretty entertaining videos with them.

The genome of the two-spot octopus turned out to carry a treasure trove of evolutionary surprises. One of the most striking discoveries was the massive expansion of protocadherin genes, which guide how neurons connect and communicate. Vertebrates like humans have them, too, but octopuses have many more. This genetic abundance appears tailored to their unusual nervous system. Roughly two-thirds of an octopus’s neurons are not in its central brain but distributed throughout its arms. Each arm can process sensory information and make decisions locally, while still coordinating with the rest of the animal.

According to Roger Hanlon, who I have worked with, octopuses are colorblind, and yet they have this remarkable ability to change color to fit their surroundings. It may be the most remarkable camouflage ability in the animal world, and yet we still understand surprisingly little about how it works. In addition to neurons, their skin and arms appear to contain opsins, light-detecting cells, raising the possibility that octopuses do not just see with their eyes, but with their bodies as well.

I mean, does it get more alien than that? That’s the stuff of serious sci-fi.

The author filming a cuttlefish in Indonesia. (Photo: Hergen Spalink)

The genome also revealed a wide set of genes involved in learning, neural flexibility, and sensory perception. Many of the same kinds of genes that support cognition in vertebrates appear in octopuses too, but they have been expanded and reworked, suggesting that evolution arrived at intelligence using a very different blueprint.

Perhaps the most surprising discovery is the octopus’s heavy reliance on RNA editing. RNA editing is the process by which cells deliberately alter RNA after it has been copied from DNA. If DNA is the master blueprint, RNA is the working set of instructions, and in octopuses that working copy can be extensively rewritten, especially in the nervous system. While other animals can do this on a small scale, this unusual molecular flexibility in the octopus may help their nervous systems adapt and respond with a level of speed and sophistication that maybe helps explain their problem-solving abilities and behavioral creativity, even if scientists are still working out exactly how it all works.

We’re really at the beginning of an effort to better understand this animal’s remarkable abilities and how it compares with our own unique intelligence. What we have learned so far is that octopus intelligence is real, measurable, and deeply unusual. In experiments, octopuses can solve puzzles, open jars, navigate mazes, remember solutions over time, and learn by watching others. Stories of octopuses escaping their tanks, squirting water at people they recognize, or slipping away from handlers they seem to dislike are surprisingly common. When I was a summer docent at the National Museum in Washington D.C. many years ago, there was an octopus that would greet me by draping an arm over the edge of the glass whenever I came in. Walking up to the tank felt less like approaching an exhibit and more like being welcomed by a friend.

Yes, I know, there is real danger in anthropomorphizing animals.

Many of my friends who are aware of my love for these animals beseeched me to watch My Octopus Teacher, the Oscar-winning documentary film. I’ve seen it twice, and I have to say that while I love many of the shots and scenes in the film, I feel like the movie goes way overboard making these animals seem like they have human emotions. I’m not sure they do. Something else is going on, I’m just not sure what it is.

If you’d like a good book on the subject, I’d recommend Other Minds: The Octopus, the Sea, and the Deep Origins of Consciousness by Peter Godfrey-Smith. It’s got more actual science in it than Sy Montgomery’s The Soul of an Octopus: A Surprising Exploration into the Wonder of Consciousness, which, like My Octopus Teacher, kind of annoyed me.

All of this is to say that we are blessed here in California to have such an amazing species in our local waters. The California two-spot octopus is more than an interesting coastal species; it is a window into how minds can form in ways we never imagined. Its genome offers clues to the very nature of intelligence, demonstrating that cognition can arise from wholly different evolutionary routes. In that sense, studying this unassuming little animal on our shoreline may be the closest we come to understanding an alien mind without ever leaving Earth.

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Upwelling, the Ocean’s Engine Beneath California’s Waters

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I recently revisited a book I enjoyed: The Blue Machine by physicist, oceanographer, and writer Helen Czerski. It is a beautifully clear exploration of the deep mechanics of the ocean and why those processes are so essential to keeping our planet cool, biodiverse, and stable.

One of the core ideas she returns to is ocean upwelling, a process that is especially important for those of us who live in California. Upwelling is one of those hidden forces that quietly underlies everything around us, and once you read about it, you realize that so much of what we know and love here simply would not exist without it.

Few marine processes are as impactful on the abundance of sea life off the coast of California as upwelling. It may not be a term you’ve heard before, but the natural oceanic process of upwelling is one of the most important engines driving climate, biological diversity, and the ocean’s food web.

It’s time to pay attention.

The abundance of sea life around some of California’s oil rigs is due in part to ocean upwelling near the continental shelf. (Photo: Erik Olsen)

In simple terms, upwelling is when cold, nutrient-rich water from the deep ocean rises to the surface, replacing warmer surface water. A churn. Along the California coast, prevailing northerly winds push surface waters offshore through the Coriolis effect, allowing deeper, colder water to rise in their place. Over the continental shelf off shore California, this upwelled water is rapidly brought into shallower depths, delivering nutrients directly into the photic zone where phytoplankton can grow. This is one reason continental shelves, including areas around offshore oil platforms (which I wrote about a few weeks ago), are biological hotspots.

California’s upwelling system is one of the most intensively studied in the world because it fuels the region’s crazy marine productivity.

In California, upwelling occurs year-round off the northern and central coast. It’s strongest in the spring and summer when northwesterly winds are at their most powerful. Upwelling is reduced in the fall and winter when winds are more variable.

Killer whales benefit from upwelling because the nutrient-rich waters fuel a surge in phytoplankton, which triggers an increase in the populations of smaller prey fish and marine mammals that orcas rely on for sustenance. (Photo: NOAA)

Researchers from institutions like the Scripps Institution of Oceanography and Stanford University have used a variety of methods, including satellite observations and computer modeling, to study upwelling. One of the groundbreaking studies was the CalCOFI program (California Cooperative Oceanic Fisheries Investigations), which began in the late 1940s. It was a joint venture between Scripps and state and federal agencies to investigate the collapse of the sardine fishery. The study showed that the sardine collapse was not just due to overfishing but also large-scale ocean and climate variability, a finding that reshaped fisheries science. Over decades, it has expanded its scope and now provides invaluable long-term datasets that help scientists understand upwelling and its impacts on marine populations.

Deep, cold ocean water is rich in nutrients because organic matter from the surface sinks as it dies or is consumed, and is broken down at depth, releasing nutrients back into the water. When that water is brought to the surface through upwelling, it delivers a fresh supply of nutrients that fuels phytoplankton growth and supports the entire marine food web.

The food web is kind of like a ladder. Or a chain. Nutrient-rich cold waters support blooms of phytoplankton: microscopic, photosynthetic organisms (meaning they are teeming with chlorophyll) that produce oxygen and form the base of marine food webs. When these primary producers flourish, it triggers a chain reaction throughout the ecosystem: zooplankton feed on phytoplankton, small fish feed on zooplankton, and larger predators, including fish, marine mammals, seabirds, (and humans) reap the rewards! So a well functioning upwelling system is pretty important for abundant sea life.

Also, cold water holds more dissolved gases like oxygen compared to warm water (yet another reason that warming seas could be a problem in the future). Oxygen is crucial for marine animals. In cold, oxygen-rich environments, organisms can efficiently carry out metabolic processes, which leads to higher rates of feeding, growth, and reproduction, thereby further boosting biological productivity. Everyone wins!

But there’s a problem.

Sardines off the coast of California (Photo: NOAA)

Studies have shown that natural changes in climate, like El Niño and La Niña events have a significant impact on wildlife and the local ocean ecosystem. During El Niño events, warmer waters and weaker upwelling reduce nutrient levels in the California Current, lowering phytoplankton productivity and causing deadly ripples through the food web. La Niña conditions generally strengthen upwelling, bringing nutrient-rich water to the surface and boosting marine productivity.

Climate change adds a potentially dangerous new layer of uncertainty: oceans are warming and growing more acidic, which can disrupt the timing, strength, and benefits of upwelling. While climate change does not necessarily mean more El Niño years, it does mean that El Niño events now play out in a warmer ocean, often amplifying their impacts and increasing stress on marine life, with serious consequences for some organisms.

Sea lions off the Southern California coast. (Photo: Erik Olsen)

We’ve been seeing some of these impacts. Take sea lions and large fish populations. In years of strong upwelling, prey is more abundant and closer to shore, allowing California sea lions to forage more efficiently and increasing populations. During weak upwelling years, prey becomes scarcer and more dispersed, forcing sea lions to travel farther for food, increasing stress and reducing reproductive success. Variations like this have been observed in recent years during El Niño periods along the California coast, showing how quickly marine ecosystems respond to shifts in ocean conditions.

Of course, upwelling isn’t just a California thing; it’s a global phenomenon that occurs in various parts of the world, from the coasts of Peru to the Canary Islands. It serves a similar churning life inducing function in these places, too. But California is sort of the poster child for scientists thanks to extensive research here and its vital role in a multi-billion dollar fishing industry that includes species like albacore tuna, swordfish, Dungeness crab, squid, and sardines.

Anacaps Island in California’s Channel Islands (Photo: Erik Olsen)

Upwelling is one of those critical oceanic processes that helps maintain our stable and immensely productive California waters, but warming ocean temperatures and changes in wind patterns could cause big problems, disrupting the timing and intensity of upwelling, putting sea life off California’s coast at risk.

Pick up some California wildlife gifts at our Etsy store. Seriously, they’re cool.

Of course, I do not mean for this piece to be yet another downer about climate change. California’s coastal ecosystem is, in many ways, healthier today than it has been in decades, thanks to policies and practices put in place once we began to understand what was truly at stake. Whenever I get offshore and experience the ocean firsthand, I feel deeply grateful for what we have now, even as I remain aware that it is something we could still damage if we’re stupid and careless…which is not out of the question. The encouraging part is that Californians have shown, again and again, a real capacity to rally when it matters. For now, then, it is worth appreciating what we have and getting out there to experience it whenever you get the chance.

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Transforming California’s Oil Platforms into Marine Sanctuaries

An abundance of sea life is thriving on the substructure beneath the Eureka oil rig in Southern California (Erik Olsen)

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If I told you that some of the richest, densest communities of marine life anywhere in the world thrive off California, you might not be surprised. We all know California has a vibrant marine ecosystem offshore. But if I told you that much of that life clings to the submerged steel legs of offshore oil rigs, you might pause, blink, and say: really?

The answer is yes.

I know because I have dived a few of them several times. Most recently this November, when I took a dive boat called the Giant Stride out of San Pedro and motored 12 miles out to the Eureka platform, which sits in 700 feet of water. From the deck, the rig looms like a floating city of steel and shadow, its massive pylon legs disappearing into the depths below.

The Eureka oil rig off the coast of California from the Giant Stride dive boat. An industrial behemoth above water, beneath, it is home to an immense diversity of sea life. (Photo: Erik Olsen)

But below the surface is another world, one teeming with millions of colorful fish, including blazing orange garibaldi, schools of dark blue blacksmiths, halfmoons, calico bass, yellowtail, and even the occasional mola mola or sunfish. A few rigs are the playground of scores of jubilant sea lions, many of them precocious youngsters that swoop and spin in the waters beneath the massive structure of the rigs like children let loose in a grassy park.

Playful sea lions frolic around the rigs beneath the surface. (Photo: Erik Olsen)

And then there are the pylons themselves and the life they support. Made of welded steel, these massive structures hold the entire oil platform above the water, millions of tons of machinery and deck space, often topped by a helicopter pad, all balanced on the integrity of engineering. Some descend straight down into the darkening waters, while others are reinforced by diagonal braces and horizontal crossbeams, a lattice of intersecting steel that keeps the rig steady against waves and wind.

But up close, you can hardly make out the metal. The substructure is so encrusted with life, layers of scallops, brittle stars, mussels, anemones, barnacles, and sponges, that the steel beneath has vanished into a living reef. In some areas, there are thousands of brittle stars clinging to the structure, they lie so thick on it that it’s hard to imagine how they compete for food. But food here is plentiful, and that abundance is one reason these rigs harbor so much life. They stand near the edge of the continental shelf, where the seafloor plunges into deeper water and cold, nutrient-rich currents surge upward toward the light. Those nutrients ignite blooms of plankton, feeding swarms of tiny crustaceans and filter feeders that coat the rig’s pilings. Those smaller creatures, in turn, sustain fish, sea lions, and even passing seabirds, a food web in full expression, built around the steel spine of an oil platform.

Brittle stars, mussels and other oprganisms blanket the rig supports in incredible numbers. (Photo: Erik Olsen)

All of this is not just my observation, however. Numerous studies have been done about the life on the rigs and most of them point to an astonishing fact: these rigs are some of the most productive ecosystems on the planet. In one study, University of California Santa Barbara marine biologist Milton Love and his colleagues found that certain platforms, including Eureka, produced more fish biomass per square meter than even the most productive natural environments in the world. More than mangroves, coral reefs, estuaries, etc.

The Eureka rig off the coast of Southern California. Once built to pump oil, it’s now also home to sea lions, fish, and a reef of life growing on its legs below the waves. (Photo: Erik Olsen)

This is good news for everyone. But there’s more. Other research suggests that the life flourishing on these offshore rigs doesn’t stay confined to them; it drifts, swims, and spawns its way back toward the coast, helping to replenish nearshore habitats. Rockfish are a perfect example. Once severely overfished, several species have made a remarkable comeback in California waters, perhaps due in part to these structures. As we wrote recently, the recovery of rockfish is one of the state’s quiet success stories.

But there’s a hitch.

Several of these rigs are now nearing, or have already reached, the end of their productive lifespan, meaning that they no longer produce much oil. What should be done with them? In California, when offshore oil rigs reach the end of their productive life, state law mandates their decommissioning, which involves safely plugging wells, dismantling structures, and restoring the environment. Traditionally, this has meant full removal of the platform and associated infrastructure: a very expensive proposition, likely costing in the billions of dollars.

Clusters of mussels and strawberry anemones (Corynactis californica) coat the rig’s submerged structure in a dense mosaic of color. They form living carpets over the steel, while mussels, bryozoans, and brittle stars fill the gaps between them. (Photo: Erik Olsen)

However, the California Marine Resources Legacy Act (AB 2503), enacted in 2010, introduced an alternative known as the “rigs-to-reefs” program. This legislation allows oil companies to apply for permits to partially remove decommissioned rigs, essentially shearing off the part of the structure above water and leaving a portion of it underwater to serve as artificial reefs. Obviously they’d do it deep enough, about 80 feet, that the structure would not become a hazard to ship traffic. The goal is to enhance marine habitats by preserving the ecosystems that have developed around these structures over time. Rig removal is a growing billion-dollar-a-year business, and by removing only part of the rig and leaving behind the rest, an oil company can save millions in decommissioning costs.

As of January 2024, there are eight offshore production platforms in various stages of decommissioning; several have had multiple owners and operators. It’s complicated, but the biggest issue is liability. That is, what happens down the line when there is a leak, or if the plugging of the wells was done improperly? Who pays for that? This is all being hashed out, as it has been for some 20 years now. Californians hate oil washing up on their beaches. Many hate the idea of the oil companies getting a financial break after plundering the sea floor for oil. But there is no denying that all that life is there. You can see it. And, as Milton Love said: “If you remove a platform, you may be killing tens of millions of animals because they happened to settle on steel instead of a rock. Which I think is a tragedy.”

Substructure of the Eureka rig above water in California (Erik Olsen)

Oil companies have not used California’s Rigs-to-Reefs law because it leaves them financially and legally burdened. They must keep long-term liability for the structures and give up to 80 percent of their cost savings to the state, which makes full removal simpler and less risky than the complex and politically sensitive reefing process.

And so, as some of these platforms near the end of their productive lives, a significant debate has emerged over their future. Should they be removed entirely, or could they be repurposed into artificial reefs that continue to support marine biodiversity? The discussion is not just about engineering challenges or environmental concerns; it’s about reimagining the relationship between human infrastructure and the natural world.

Amber Sparks led the expedition I took out to the rigs. I’ve dived with her several times before and believe she’s a passionate advocate for sea life and for a healthy offshore California marine ecosystem. She and her co-founder Emily Hazelwood are strong supporters of reefing the rigs, and through their work with Blue Latitudes, they collaborates with scientists, government agencies, and oil companies to explore ways decommissioned platforms could be transformed into permanent marine habitats rather than dismantled and removed.

“The big question is, are these structures good habitat that should be left in place to continue to thrive as reefs, or should they be removed? In my opinion, they would be really valuable to be left in place as reefs.”

A brittle star falls through the water column beneath the Eureka rig (Erik Olsen)

So where do things stand today? A December 2023 Public Environmental Impact Statement (PEIS) from the Bureau of Safety and Environmental Enforcement and Bureau of Ocean Energy Management marks the most recent major development in the offshore rig debate, and it could significantly shape future decommissioning of California’s oil platforms. Though the PEIS identifies partial removal as the environmentally preferable option (italics mine) because it would preserve the habitat of existing biological communities, the agencies involved selected “Alternative 1a”, mandating complete removal of platform jackets and associated infrastructure offshore southern California. The final decision over what to do with the rigs has not yet been made, but the current wisdom suggests that they may have to go. As a diver and novice fisherman, I consider this a shame.

Public opposition to “big oil” remains strong in California, fueling demands among small but vocal groups for the complete removal of oil rigs, despite the potential loss of coral-like ecosystems. Environmental groups like the Natural Resources Defense Council argue that retaining any portion of these structures enables the oil industry to persist as an environmental threat.

Beneath the surface of a California oil rig, a vibrant colony of pink strawberry anemones transforms industrial infrastructure into an underwater oasis. (Erik Olsen)

“People here have been waiting for these oil platforms to go away,” Linda Krop, an environmental lawyer with the Environmental Defense Center, an advocacy group based in Santa Barbara, told the me when I reported on this for the New York Times. Ms. Krop challenged the notion that the science definitively supports the role of rigs in fostering marine life. She argued that leaving the rigs in place would effectively reward polluters by allowing them to avoid the expense of removal.

Globally, the concept of Rigs-to-Reefs has seen success, particularly in the Gulf of Mexico, where over 500 platforms have been converted into artificial reefs. These structures have become magnets for fish and invertebrates, supporting commercial and recreational fishing and diving industries. However, critics argue that not all programs are created equal. In some regions, lax regulations have allowed oil companies to avoid fully addressing environmental risks, leaving behind structures that degrade over time and release pollutants. California’s approach, with its stringent oversight and commitment to environmental benefits, aims to avoid these pitfalls while maximizing ecological gains.

The oil rigs substructure provides a fascinating contrast to the life on large sections of it. (Erik Olsen)

What happens to California’s oil platforms will reveal how the state chooses to balance economic legacy with ecological responsibility. Few would argue that oil companies deserve further rewards after decades of drilling and profits, yet the decision ahead is not so simple, it is about what becomes of the ecosystems that have grown around their steel foundations. There should be a way to move forward responsibly, one that removes the risk and legacy of drilling while preserving the thriving marine life that has made these structures their home.

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San Clemente Island is Where War Games and Wildlife Coexist

Loggerhead Shrike (Photo: US Fish and Wildlife Service)

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A few months ago, I took a fishing trip out to the western side of San Clemente Island. I woke at two in the morning to the rattle of the anchor chain dropping and stepped out onto the deck, expecting darkness all around us. Instead the night was alive with a strange glow. Dozens of squid boats floated offshore, their powerful lights illuminating the water with a bluish, Avatar-like brightness. The lights draw squid toward the surface before the crews scoop them up in nets.

As I knew from earlier research, and from being a long-time California resident, squid are one of California’s top commercial fisheries, a multimillion-dollar industry built around what is known as market squid. They thrive in enormous numbers in the deep waters around the Channel Islands and up toward Santa Barbara, even though the average beachgoer rarely thinks about them. From the rail of the fishing boat I was I could see vast swarms just below the surface.

Squid boat off shore San Clemente Island (Photo: Erik Olsen)

When dawn broke, San Clemente Island emerged ahead of us, and I was struck by how stark and empty it looked. In both directions stretched the same raw, rugged coastline, with almost no sign of human presence (there were what appeared to be radio towers on the top of a peak, but no people).

It felt desolate and otherworldly. But the reality is more complicated.

The island is part of the Channel Islands, a chain that trends east to west rather than the usual north–south pattern of most California ranges. The Channel Islands are often called North America’s Galápagos because they support an extraordinary number of species found nowhere else, shaped by the deep isolation that defines island biogeography (we wrote about this earlier).

San Clemente is no exception. The island is abundant in wildlife, with its own collection of rare plants and animals. But what makes it stand apart from the other islands is the scale of the military activity just beyond the barren cliffs. The U.S. Navy conducts constant training here, including missile tests, amphibious landings, and live-fire exercises. The island is considered one of the most important training grounds for the United States military, operating around the clock even as endangered species cling to survival in the canyons and plateaus nearby.

San Clemente Island looks like a long volcanic ridge from offshore, but it has been one of the most important and least visible military landscapes in California for almost a century. It is the southernmost of the Channel Islands and has been owned entirely by the U.S. Navy since the late 1930s. Over time it became a central part of Naval Base Coronado, and today its main airfield supports helicopters, jets, drones, and special operations teams that rotate through the island throughout the year.

It all seemed really interesting. I desperately wanted to go ashore, but if I’d tried, I almost certainly would have been arrested.

Live fire training exercises with mortars on San Clemente Island Photo: (Spc. William Franco Espinosa / U.S. Army National Guard)

The island began shaping military history just before World War II. In 1939, naval engineers brought early versions of the Higgins boat to San Clemente Island to test how they handled surf, wind, and timing with naval gunfire. These flat-bottomed landing craft became essential to Allied victories in places like Normandy and Guadalcanal. The island’s rugged shoreline helped the US military refine the tactics behind the amphibious assaults that defined twentieth century warfare.

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During the Cold War, San Clemente Island evolved into one of the Navy’s busiest live fire training sites. The waters around Pyramid Cove hosted decommissioned ships used as targets. Carrier air wings practiced bombing runs across the southern plateau. Marine units rehearsed ship-to-shore landings on isolated beaches, while submarines conducted simulated missions under restricted airspace. We did a short video you can watch here.

Few places on the West Coast allowed sea, air, and land forces to operate together with real weapons, and the island’s remoteness made it ideal for rehearsing missions that couldn’t take place near populated coastlines. Yet all of this is happening just about 60 miles offshore from Los Angeles. (It took us about five hours to get back).

Civilian access has always been extremely limited, which is why the island only reaches the news when something unusual happens. One widely reported event occurred in 2023, when a private pilot illegally landed a small plane on the island’s runway and then stole a Navy truck before being detained. He tried again in 2025. This kind of thing underscores how isolated and tightly controlled the installation is. For the most part, the only people who ever set foot on the island are service members using it as a sophisticated, real world training environment.

Oh, and scientists, too.

That’s because the island’s natural history has been studied intensively. Decades ago, ranching introduced goats, sheep, and invasive plants that stripped vegetation from entire hillsides. Feral cats and rats preyed greedily on ground nesting birds, and live fire exercises fragmented habitat. By the 1970s and 1980s, San Clemente Island held one of the highest concentrations of endangered species in California, but everything was under threat.

San Clemente Island looks otherworldly and barren from a fishing boat (Photo: Erik Olsen)

Enter the U.S. Fish and Wildlife Service, which worked with the military to balance military readiness with the legal requirements of the Endangered Species Act. And it’s been, by many measures, a pretty major success.

No species became more symbolic of the struggle to protect the island than the San Clemente loggerhead shrike, a lovely, black masked songbird that lives nowhere else on Earth. By the late 1990s its wild population had fallen to as few as fourteen individuals. The Navy funded a comprehensive recovery effort that included captive breeding, predator removal, and habitat reconstruction, all with the expertise help of the San Diego Zoo Wildlife Alliance. By restoring vegetation and extensive breeding, scientists released shrikes which eventually began to hunt, build territories, and raise their young. The species is now considered one of the most successful island bird recoveries in North America.

The San Clemente Island fox, once threatened by habitat loss and predation, has rebounded significantly thanks to intensive conservation efforts that stabilized its population and restored its native ecosystem. (Photo: USFWS)

And that wasn’t the only success. Once goats and sheep were removed, native shrubs and herbs began returning to the island. Endemic plants such as the San Clemente Island lotus and San Clemente Island paintbrush, responded quickly once the pressure from grazing disappeared. In 2023, after decades of habitat recovery, the Fish and Wildlife Service announced that five island species were healthy enough to be removed from the endangered species list, a pretty cool milestone that suggested a major ecological turnaround for San Clemente and the Channel Islands as a whole.

San Clemente Island lotus (Photo: USFWS)

Today, San Clemente Island remains one of the most unusual places in California. It is a live fire training range where carrier groups, SEAL teams, and Marines rehearse some of the most complex operations in the Navy. It is also a refuge where rare birds and plants have recovered after hovering near extinction. Conservation biologists and military planners now coordinate schedules, field surveys, and habitat protections to keep both missions intact. There’s an excellent documentary on this recovery effort made by SoCal PBS.

California has become a national leader in restoring damaged ecosystems. And while the state has lost much of its original wildness over the centuries, it also offers some of the most compelling examples of species and habitats recovered from the brink. San Clemente Island is more ecologically stable today than at any point in the past century, and it continues to serve as one of the Navy’s most valuable training grounds.

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