Ascension, the desert island that became a jungle

Almost exactly halfway across the Atlantic between Africa and South America, just below the equator, lies an island that 200 years ago was uninhabited and was described by one contemporary writer as “the abomination of desolation.” “Ascension produces nothing but turtles, rats and insomnia,” another said. “The most desolate and barren land (like a land accursed by God) that ever my eyes beheld… I believe the whole world affords not such another piece of ground,” added a third. Ascension Island is so remote (800 miles from the nearest land, Saint Helena; 960 miles from the nearest point in Africa; and 1,400 miles from Brazil) that not a single seed from any plant reached it until humans — specifically the British — settled there. “There is no soil, no shade, no plants, no water,” wrote one of its first inhabitants. And yet Ascension has held enormous geostrategic importance since its discovery and, despite that desolation — or precisely because of it — now has huge environmental value. The island was also visited by the famous writer, scientist, and revolutionary of biology, Charles Darwin. Thanks to him and to a story of courage, stubbornness, biology, and engineering, this unlikely island might hold the secret to combating desertification worldwide, and a young Spanish scientist is working to test that idea.

When Napoleon was exiled to Saint Helena in 1815, the British took less than a week to occupy the neighboring island, until then uninhabited, out of sheer precaution: they feared the French might use it as a base to rescue him. Two warships claimed the island that same year for George III. But it was so desolate that the Royal Navy classified it as HMS Ascension, which, technically, made the island a ship, not dry land.

More than 200 years later, Víctor Maull begins climbing the slope of a volcano on this tiny island and the sun — until then relentless over Ascension’s lowlands — disappears behind the clouds. It soon begins to drizzle. The volcano slowly turns into woodland, then into something close to jungle. The landscape is unreal: banana plants, moss, begonias, ferns. The young Spanish scientist disappears into the thick fog, and a sheep emerges from the undergrowth. Visitors have to peer over the edge of the slope, at the lunar landscape glimpsed below, to confirm that yes, we are on a volcano. Then comes the most striking sight of the trip: fig trees some 40 meters across, draped in hanging moss and surrounded by endemic plants. At the end of the path there are more surprises: a pond and giant bamboo. When you look at the magnificent pictures accompanying this story, remember that beneath those trees, banana plants, grass and moss, there is a volcano.

In 1836, on the return voyage of the Beagle, the young naturalist Darwin stopped at this island. In his journal he recorded what Saint Helena residents said about Ascension: “We [the ‘saints,’ as they are called there] know we live on a rock, but on Ascension they live on a cinder.” On Ascension he went ashore and visited a kind of crater with concentric rings of color called the Devil’s Riding School. In his journal, Darwin speculated that the layers of ash had settled under water: during some great eruption, he believed, torrents of rain had fallen and formed a temporary lake in which the ash gradually accumulated. He compared the island to the bleakest of the Welsh mountains. And then he left without looking back.

Yet that idea — that there might once have been water on this remote, isolated piece of land — fed the dreams of another naturalist seven years later. Joseph Hooker, a botanist and close friend of Darwin, stopped on the island en route to Antarctica. He encountered the same desolation. But unlike Darwin, he did more than describe it: in 1847 he persuaded the Royal Navy to send trees from the famous Kew Gardens in London, where his father was director. The idea was as simple as it was outlandish: the trees would catch the rain, reduce evaporation and create fertile soil. The ash could become a garden and even — who knows — a jungle.

“Ascension caught our attention because it represents a transition from nothing to ecological exuberance, a unique experiment carried out in the Victorian era on a desert island,” Maull explains. That is why he decided to visit, accompanied by EL PAÍS. What if Hooker’s Ascensión approach could “open the door to thinking about under what circumstances other places in the world might be intervened in the same way?” asks the researcher, who holds a PhD in biomedicine and works at the Complex Systems Lab of the Institute of Evolutionary Biology (CSIC-UPF) and Pompeu Fabra University.

At this newspaper’s request, Maull recalls in writing his first day on the island, after years of knowing it only through papers, photos, and videos. “After flying for hours over the Atlantic, we suddenly descended and landed on this extraordinary piece of land, operated by the island’s military bases. I felt I already knew the place,” he says. “That same day we climbed one of the volcanic cones in the interior and saw Green Mountain opposite us, that peak of lush vegetation rising 800 meters out of a scorching volcanic plain. And, just as we had read, a large, water-laden cloud clung to the peak and shaded it. That cloud didn’t disappear for the whole month we were on the island, and it is the bold result of a story of science and technology,” he writes.

The scientist crosses the island from one point to another, from the green summit of Hooker’s mountain to the arid plains where Darwin also walked. Maull treads this same barren, desert-like, infertile ground and explains how Darwin’s genius deduced the existence of that vanished lake, which today can be seen perfectly from a drone. Maull is not working alone. Nastassia Knödlseder, who holds a doctorate in biomedicine and is a researcher at the Synbio Lab at the Pompeu Fabra University (UPF), applies to Ascension’s soil the same logic she normally uses for human skin: both are bacterial ecosystems that can be read and, up to a point, modified. “Microbiota is everywhere, including in the soil,” she explains. On this visit, the two scientists collected 38 soil samples to extract their DNA and analyze their chemistry: nitrogen, carbon, moisture, texture. The aim is to answer a question that makes any classical ecologist uneasy: can an ecosystem be called “mature” if it has not had time to evolve, if it was built in barely 150 years instead of the usual millennia?

In a world where stories of climate change and desertification are inevitably written from a place of pessimism, this one carries an undercurrent of hope. The technical term for it is “terraforming,” a term debased by Elon Musk when he shares his plans to colonize Mars. The ideas of Maull and scientists like him go in another direction. He explains it with an image he often uses in his talks, including one he gave to Ascension’s residents during his visit: picture a graph with an ecosystem’s percentage of vegetation on one axis and aridity on the other. Intuition says the curve should be a gentle slope (the drier, the less green, little by little). But that is not how ecology works. “It’s called a catastrophic transition,” he explains. “You fall off a cliff and end up in the desert.” The key is that this leap — what scientists call a tipping point — almost never has a way back: once the vegetation that held moisture, created shade, and built soil is lost, reversing the process requires an amount of energy and resources that, Maull says, “are often not feasible.”

We are used to thinking that life thrives wherever conditions are favorable to it, he says, looking at the barren ground around him in the volcanic part of the island. “But living beings transform the conditions of their environment and, in turn, the environment itself affects biological processes.” This phenomenon is what happened on Ascension: before the planting, the moist trade winds simply blew past. But vegetation, under certain conditions, can capture this resource and unlock it, thereby creating a completely different, habitable habitat. Maull reflects: “This transition needed human help on Ascension. Now the question is to what extent we can extrapolate it to other parts of the world, and at what cost.”

His thesis supervisor, Ricard Solé, an ICREA research professor at Pompeu Fabra University and the Institute of Evolutionary Biology (CSIC-UPF), has been working on these kinds of ideas since 2015. It is not only about understanding ecosystems on the brink of collapse, but about designing ways to intervene in them. He calls it “emergent engineering,” an intervention “carefully designed around the ecosystem that is already there,” which enhances existing biodiversity rather than replacing it. Solé insists that tipping points are not a theoretical rarity and warns that climate change is accelerating them, even faster than expected. Between 1982 and 2015, human‑caused climate change degraded 12.6% of the planet’s drylands — about 5.4 million square kilometers — affecting more than 200 million people.

Green Mountain, the one Maull is walking through, was created artificially almost 200 years ago. Hooker convinced his country to send him plants from botanical gardens in Europe, South Africa, and Argentina: the first shipment alone contained 330 different species. By the 1870s, the slope that had once been ash was covered in eucalyptus, araucaria, bamboo, and banana plants. Between 1843 and 1922, five different gardeners sent out from London took turns tending the mountain’s plantation, each serving about 10 to 15 years before leaving or dying on the job. Of John Bell, who arrived in 1857, the Royal Navy wrote in its hiring report: “He is young, healthy, unmarried and, no doubt, tolerably sober.” The longest-serving man, Hedley Cronk, spent 26 years on the island, from 1896 to 1922, and to the young soldiers of the garrison he was almost a king. He cut a path, which still bears his name, along which he liked to stroll at dusk, contemplating what he had planted. Without anyone quite planning it that way, and thanks to engineering, a self-sustaining cloud forest had been born. It was the first documented terraforming in history, 150 years before the word existed.

Maull found those gardeners’ letters in the island archives, and he admits that the search puzzled him at first. “No one was asking about the transformation of this island; nobody seemed interested.” His own explanation is that Hooker, the botanist who drove the whole project, barely mentioned it in his own journals: he was thinking about much bigger questions, discussing the theory of evolution with Darwin. “To him this was anecdotal,” Maull says. What we now see as an incredible feat of environmental engineering was, for them, all in a day’s work.

It was not a clean process. The 330 species in the first shipment were followed — unplanned — by insects that arrived stuck to the roots, birds that settled to eat them, and the rats and cats sailors introduced to control pests and that ended up becoming pests themselves. Each introduction solved one problem and created the next: a chain no one designed from start to finish and that still determines what survives on the mountain today.

That is why Maull’s thesis is controversial, even on the island itself. Tiffany Simpson, director of Conservation and Fisheries for the Ascension Island Government (AIG), says calling Green Mountain a “functional ecosystem” stretches the term. “What remains today is an unusual combination of species — bamboo, eucalyptus, ficus and others — that would never have grown or evolved together naturally in an ecosystem,” she explains from her office in Georgetown, the island’s capital. The dominant introduced species displaced the endemic ones, and the large trees — planted on soil that is still inadequate, barely a thin layer over volcanic rock — have shallow roots: in strong storms they topple, sometimes taking infrastructure with them.

Simpson and her team are engaged in the Herculean task of conserving eight of Ascension’s 10 endemic plants, unique in the world, amid a flora in which more than 95% of species are introduced or invasive. Two went extinct along the way, but the case that moves her most, she says, is Anogramma ascensionis, the Ascension Island parsley fern: it was thought to be extinct until, in 2009, four surviving specimens were found on a cliff. Since then, an enormous effort has gone into saving this little plant.

The work demands an almost artisanal patience: in the shade houses, seeds are collected from genetically distinct populations and propagated separately to avoid mixing. Then come months of gradual hardening, exposing plants slowly to more light and less water — the conditions they will face on arid Ascension. Roots must be washed by hand when mealybugs invade the soil, and water moats surround the growing tables so ants cannot reach the plants. The team works every day, plus the weeding they never quite finish. Endemic life on the island depends on a handful of people willing to spend years caring, by hand, for what others neglected.

The question that nags at Solé after seeing Simpson’s work is more ethical than technical: “They are using up thousands of liters of water and making huge efforts to conserve the few endemic plants they have left,” he says. “If we have little time, little money and little political attention, should we spend it conserving those species that, without that extra effort, would probably die? Or on thinking harder about how to improve ecosystems with what already exists, which is the invasive plants?” asks the UPF professor.

Maull has no easy answer. “Maybe that’s the Gordian knot of it all,” he replies. “We need to think of effective recovery strategies that, beyond restoring a particular state, maximize properties beneficial to all ecosystems, such as biodiversity.” He himself started out as a naturalist, attached to the conservation of rare species, and fully understands the position of someone who watches the last plant of a species with hundreds of thousands of years of history die and experiences it as a tragedy. Both he and Simpson reject the binary choice between conserving and letting nature take its course. He proposes something in between: using “facilitator trees,” harmless species that form the cloud forest canopy but leave room for endemic plants to find their niche — rather than managing the mountain as if it were an untouched Victorian forest or, at the other extreme, abandoning it to its own invasive inertia.

Can this living laboratory be exported to other volcanic or desert regions? Larger‑scale attempts have been tried, such as China’s Great Green Wall, for which 66 billion trees have been planted since 1978 to halt the advance of the Gobi and Taklamakan deserts. The project has raised regional forest cover from 5% to 14% over five decades, but not without cost: some of the plantations used poorly chosen species that grew fast but lost effectiveness, and in the driest areas the forest itself competes for water with whatever was left around it.

“Ascension is striking and shows us something we sometimes forget: ecosystems are not fixed structures but dynamic communities that can reorganize when environmental and biological conditions change,” says Fernando T. Maestre, a professor of ecology and one of the world’s leading experts on dryland ecosystems. But he cautions: “The Ascension experiment is not a model that can be directly exported to Spain or the Sahel.” To begin with, because Ascension was uninhabited. “In regions like southeastern Spain, the Sahel, or other semi‑arid zones, restoration cannot be separated from land use: agriculture, livestock, water availability, land ownership, the needs of the local population and conflicts over use,” he explains. Any intervention at Hooker’s scale would have to coexist with all that — the shepherd who needs forage for his animals, the farmer who needs water for crops, the person who owns the land to be reforested.

Ascension has its own tensions, too. It is a British Overseas Territory that hosts a British military base and a U.S. base. The island cannot be visited without permission from the AIG, the British authority that administers it. It has 918 residents, according to the latest population figures: 48% are Saints (native to Saint Helena and mostly base workers), 22% are other nationalities, 16% are American and 13% British. Under the same AIG, within just 88 square kilometers (34 square miles), coexist a European Space Agency station tracking Ariane rocket launches from French Guiana, the U.S. base, and the air base that in 1982 made Ascension the indispensable staging post for the UK’s Falklands campaign. A few months ago it made headlines when a cruise ship carrying a passenger with a hantavirus case stopped nearby.

Rowan Laxton is the island’s administrator and he does not mince words about the underlying problem. “We can’t carry on as we are now.” Ascension runs a deficit of just over £1 million a year ($1.34 million). Is it necessary for the island to keep investing in conservation? The declaration of the marine protected area in 2019 was a major environmental achievement, but it came with a direct opportunity cost: it ended the revenue previously generated by commercial fishing licences.

Georgina Wilson taught geography at the island’s school for two years before moving to the Administrator’s Office; in her spare time she also runs the Heritage Society, the small organization trying to preserve what little remains of Ascension’s physical memory. Her partner, Neil Lawrence, a Saint, says he would like to see more funding for the island’s historic buildings, among them the old barracks where the workers who planted Green Mountain lived, and the historic NASA building from which the Apollo 11 mission was monitored.

Because the island urgently needs money, Laxton talks about opening it up — not to mass tourism, he insists, but to science. “There are always scientists here,” he says, from universities around the world, studying everything from birds to geology, turtles, stars, and plants. He recounts a recent conversation with Sir David King, former chief scientific adviser to the UK government: when Laxton mentioned the figure needed to build an international research center (“a million pounds,” he says), King told him he was looking at the problem the wrong way around. He should think instead about where Ascension is: in the middle of the Atlantic, on the migratory routes of whales and turtles, on the path of tuna crossing half the ocean. It is also a place of great strategic importance for communications and space. And it has Green Mountain, a living model of real terraforming. It is not a small island in need of charity, but one that could become a vital hub open to international scientific research.

Science cannot yet determine which way the story of Ascension’s Green Mountain will turn. Is it a story of the triumph of the human mind and knowledge on an increasingly unlivable planet — one to which, perhaps, solutions might be applied to transform it, after we have wrecked it? Or is it the story of a biological Frankenstein’s monster, created by Victorian minds who never cared about preserving the precious endemic species of an island in the middle of the Atlantic, and which now has to be fixed? The only thing that is clear for now is that nature can be saved, healed, and even created — but not without a cost.

Sign up for our weekly newsletterto get more English-language news coverage from EL PAÍS USA Edition