[Editors Note:  This article originally appreared in The New Yorker for the April 18, 2016 issue]

By Elizabeth Kolbert

Ruth Gates fell in love with the ocean while watching TV. When she was in elementary school, she would sit in front of “The Undersea World of Jacques Cousteau,” mesmerized. The colors, the shapes, the diversity of survival strategies—life beneath the surface of the water seemed to her more spectacular than life above it. Without knowing much beyond what she’d learned from the series, she decided that she would become a marine biologist.

“Even though Cousteau was coming through the television, he unveiled the oceans in a way that nobody else had been able to,” she told me.

Gates, who is English, ended up studying at Newcastle University, where marine-science classes are taught against the backdrop of the North Sea. She took a course on corals and, once again, was dazzled. Her professor explained that corals, which are tiny animals, had even tinier plants living inside their cells. Gates wondered how such an arrangement was possible. “I couldn’t quite get my head around the idea,” she said. In 1985, she moved to Jamaica to study the relationship between corals and their symbionts.

It was an exciting moment to be doing such work. New techniques in molecular biology were making it possible to look at life at its most intimate level. But it was also a disturbing time. Reefs in the Caribbean were dying. Some were being done in by development, others by overfishing or pollution. Two of the region’s dominant reef builders—staghorn coral and elkhorn coral—were being devastated by an ailment that became known as white-band disease. (Both are now classified as critically endangered.) Over the course of the nineteen-eighties, something like half of the Caribbean’s coral cover disappeared.

Gates continued her research at U.C.L.A. and then at the University of Hawaii. All the while, the outlook for reefs was growing grimmer. Climate change was pushing ocean temperatures beyond many species’ tolerance. In 1998, a so-called “bleaching event,” caused by very warm water, killed more than fifteen per cent of corals worldwide. Compounding the problem of rising temperatures were changes in ocean chemistry. Corals thrive in alkaline waters, but fossil-fuel emissions are making the seas more acidic. One team of researchers calculated that just a few more decades of emissions would lead coral reefs to “stop growing and begin dissolving.” Another group predicted that, by midcentury, visitors to places like the Great Barrier Reef will find nothing more than “rapidly eroding rubble banks.” Gates couldn’t even bring herself to go back to Jamaica; so much of what she loved about the place had been lost.

But Gates, by her own description, is a “glass half full” sort of person. She noticed that some reefs that had been given up for dead were bouncing back. These included reefs she knew intimately, in Hawaii. Even if only a fraction of the coral colonies survived, there seemed to be a chance for recovery.

In 2013, a foundation run by Microsoft’s co-founder Paul Allen announced a contest called the Ocean Challenge. Researchers were asked for plans to counter the effects of rapid change. Gates thought about the corals she’d seen perish and the ones she’d seen pull through. What if the qualities that made some corals hardier than others could be identified? Perhaps this information could be used to produce tougher varieties. Humans might, in this way, design reefs capable of withstanding human influence.

Gates laid out her thoughts in a two-thousand-word essay. The prize for the contest was ten thousand dollars—barely enough to keep a research lab in pipette tips. But after Gates won she was invited to submit a more detailed plan. Last summer, the foundation awarded her and a collaborator in Australia, Madeleine van Oppen, four million dollars to pursue the idea. In news stories about the award, the project was described as an attempt to create a “super coral.” Gates and her graduate students embraced the term; one of the students drew, as a sort of logo for the effort, a coral colony with a red “S” on what might, anthropocentrically, be called its chest. Around the time the award was announced, Gates was named the director of the Hawaii Institute of Marine Biology.

“A lot of people want to go back to something,” she told me at one point. “They think, If we just stop doing things, maybe the reef will come back to what it was.”

“Really, what I am is a futurist,” she said at another. “Our project is acknowledging that a future is coming where nature is no longer fully natural.”

The Hawaii Institute of Marine Biology occupies its own tiny island, known as Moku o Lo‘e, or, alternatively, Coconut Island. In the nineteen-thirties, Moku o Lo‘e was bought by an eccentric millionaire who fashioned it into an insular Xanadu. He installed a shark pond, a bowling alley, and a shooting gallery, and threw elaborate parties with guests like Shirley Temple and Amelia Earhart. After falling into decline, Moku o Lo‘e was rediscovered by Hollywood in the nineteen-sixties. TV producers used it in the opening sequence of “Gilligan’s Island.”

The first time I made the trip, it was a beautiful morning. I found Gates in a lab building that, from the outside, looks like a budget motel. She is fifty-four, with a round face, short brown hair, and a cheerfully blunt manner. Her office is spare and white; the only splash of color comes from a single painting—a seascape done on a piece of corrugated metal—that is the work of her partner, an artist and designer. The office looks out over the bay and, beyond it, to a dusty brown military base—Marine Corps Base Hawaii. (The base was bombed by the Japanese minutes before the attack on Pearl Harbor.)

Gates explained that Kaneohe Bay was the inspiration for the “super coral” project. For much of the twentieth century, it was used as a dump for sewage. By the nineteen-seventies, a majority of its reefs had collapsed. A sewage-diversion program led to a temporary recovery, but then invasive algae took over and the water turned into a murky soup.

In 2005, the state teamed up with the Nature Conservancy and the University of Hawaii to devise a contraption—basically, a barge equipped with giant vacuum hoses—to suck algae off the seabed. Gradually, the reefs revived. There are now more than fifty so-called “patch reefs” in the bay.

“Kaneohe Bay is a great example of a highly disturbed setting where individuals persisted,” Gates said. “If you think about the coral that survived, those are the most robust genotypes. So that means what doesn’t kill you makes you stronger.”

In one set of experiments planned for the super-coral project, corals from Kaneohe Bay will be raised under the sorts of conditions marine creatures can expect to confront later this century. Some colonies will be bathed in warm water, others in water that’s been acidified, and still others in water that’s both warm and acidified. Those which do best will then be bred with one another, to see if the resulting offspring can do even better.

The power of selective breeding is all around us. Dogs, cats, cows, chickens, pigs—these are all the products of generations of careful propagation. But the super-coral project pushes into new territory. Already there’s a term for this sort of effort: assisted evolution.

“In the food supply, in our pets, you name it—everywhere you turn, selectively bred stuff appears,” Gates observed. “For some reason, in the framework of conservation—or an ecosystem that would be preserved by conservation—it seems like a radical idea. But it’s not like we’ve invented something new. It’s hilarious, really, when you think about it.”

Coral reefs are found in a band that circles the globe like a cummerbund. The band stretches from the Tropic of Cancer to the Tropic of Capricorn, though there are occasional reefs at higher latitudes—near Bermuda, for instance. The world’s largest reef, or really reef system, is the Great Barrier Reef, along the east coast of Australia. Reefs can be hundreds of feet tall and thousands of acres in area. Unlike the Great Wall of China, the Great Barrier Reef, which extends more than fourteen hundred miles, actually is visible from space.

The architects of these vast structures are difficult to see with the naked eye. Known infelicitously as polyps, individual corals are generally no more than a tenth of an inch or so across. They consist of a set of tentacles—either six or a multiple of six—arrayed around a central mouth. Corals can, in effect, clone themselves, so a typical polyp is surrounded by—and also attached to—thousands of other polyps that are genetically identical to it. Many are also hermaphrodites; they produce both eggs and sperm, which they release once a year, in the summertime after a full moon. The polyps live in a thin layer at the surface of a reef; the rest of the structure is essentially a boneyard, composed of the exoskeletons of countless coral generations.

One day, when I was hanging around Moku o Lo‘e, Gates offered to show me some polyps close up, through a state-of-the-art machine known as a laser scanning confocal microscope. The confocal is so elaborate that its many lenses and screens and beam splitters take up an entire room, and it’s so complicated that Gates had to call in a colleague—a molecular biologist named Amy Eggers—to run the thing.

“It’s a very dynamic little world,” Eggers observed. She upped the magnification, and I could make out the nematocysts, or stinging cells, at the tip of each tentacle. I could also see the corals’ minute plant symbionts. Under the laser, these showed up as bright-red dots, so that the polyps seemed to be glowing from within. As the polyps grew more active, I found myself investing them with little gelatinous personalities. One was waving particularly vigorously, as if trying to attract attention.

“You can imagine what happens when people step on them,” Eggers said. “I try not to think about that.”

Although corals can’t travel, they practice a highly effective version of hunting and gathering. Their nematocysts contain minute poisonous barbs; these they use to spear tiny planktonic prey, which they then stuff into their mouths. (Some corals also deploy nets made of mucus to nab their victims.) Meanwhile, their symbionts are producing sugars, via photosynthesis. The symbionts allow the bulk of these sugars to leak into the corals, an arrangement that, in human hunter-gatherer terms, might be compared to finding a tree that harvests and delivers its own fruit.

The efficiency of the symbiotic relationship is what makes reefs possible: the sugars released by their symbionts power the corals’ massive building projects. These projects, in turn, foster many other relationships—far more than marine biologists have been able to understand, or even catalogue.

Owing to Gates’s many administrative duties—in addition to running the marine-biology institute and her own lab, she’s the president of the International Society for Reef Studies—she spends a lot of her time in meetings. Whenever she has a chance, though, she jumps into the water. Another day when I was hanging around the island, Gates offered to take me with her.

It was a beautiful Hawaiian morning, but the bay, in midwinter, was cool enough that Gates recommended borrowing a wetsuit. The only suit in my size was an extra-thick one; getting into it made me empathize with any animal that’s ever been eaten alive by a boa. I finally managed to zip it, and Gates and I and two of her students set off in a fibreglass boat.

Our first stop was a reef nicknamed the Fringe. “Wow, there’s a lot of mortality,” Gates said as we anchored nearby. We put on masks and plopped into the water. When she got right up to the reef, Gates brightened.

“Wherever it’s still brown, it’s living tissue,” she told me. She pointed to a large colony of Montipora capitata, or rice coral, that was sporting a plastic tag. Much of it was covered with olive-colored algae, which looked like ratty shag carpet. But there were also lots of clumps of beige.

“It’s really heartening to see these reefs be so resilient,” Gates said.

We swam along. It was hard for me to tell what represented a sign of resilience and what didn’t, since I wasn’t entirely sure what I was looking at. Ribbons of bright orange, which I took to be a show of health, turned out to be the opposite—a species of invasive sponge, introduced from Australia. What struck me most about the reef was what was absent. Aside from an occasional—and spectacular—yellow tang, there were almost no fish. When I asked Gates about this, she said that it was the legacy of decades of overfishing. This was yet another problem for the corals, which depend on herbivores to keep down the algae that compete with them for space.

We pulled ourselves back onto the boat and motored on. We were in the flight path of the Marine base, and every few minutes a plane either landing or taking off screamed above us, trailing a cloud of black smoke.

The colors of a healthy reef are a sign of harmony. Polyps are transparent; it’s the microscopic plants living inside them that give them their ruddy hue. In very warm water, these tiny plants, which belong to the genus Symbiodinium, go into what might be described as photosynthetic overdrive. At a certain point, they produce so much oxygen that they threaten their hosts. To defend themselves, the polyps spit out (or slough off) their symbionts and turn white—hence the term bleaching.

In the summer of 2014, unusually high water temperatures in the Pacific caused widespread bleaching around Oahu. Reefs in Kaneohe Bay were particularly hard hit; an underwater video shot in the bay in October, 2014, shows colony after colony of stark white coral.

In the summer of 2015, water temperatures in Kaneohe Bay spiked again, by almost four degrees Fahrenheit. This time, the event was linked to a huge shape-shifting pool of warm water that became known as the Blob. Some of the bay’s corals hadn’t recovered from the first bleaching; many of those which had been rallying were once again laid low.

“At the height of the bleaching events in 2014 and 2015, we all went into the water and said, ‘Shit!’ ” Gates told me. “Two bleaching events in a row—that’s outrageous.”

Though Gates certainly hadn’t planned on back-to-back bleaching episodes when she proposed the super-coral project, in a perverse sort of way they turned out to be godsends. She wouldn’t have to design a test to find the toughest corals; the bay had performed that task for her, separating colonies that could withstand repeated bleaching from those which couldn’t.

In the bit of reef we were looking at in the Keyhole, this sorting process had played out with peculiar vividness. The three colonies, right next to one another, had been subject to the same water temperatures. What had distinguished the quick from the dead? Perhaps the colonies were, in some small but critical way, genetically distinct. Or perhaps the difference was epigenetic. Epigenetics is to genes what punctuation is to prose; epigenetic changes alter the way genes are expressed but leave the underlying code unaffected. Or the fault may lie not in the corals themselves but in their symbionts. There are dozens of strains of Symbiodinium, and different ones seem to be associated with different levels of heat tolerance.

Gates is hoping to explore all these possibilities. The aim of her project is not just to create a super coral but also to investigate whether corals that aren’t super can be trained, as it were, to do better. She believes that it may be possible to coax young corals to take up new symbionts, not unlike the way parents encourage children to make new friends. She also believes that exposure to moderately high temperatures induces epigenetic changes that can help corals withstand very high temperatures. If so, then she thinks it might be possible to “condition” reefs by dousing them with hot water. “Yes, it might be logistically quite difficult to do,” she told me. “But an engineer would be able to solve that problem in a heartbeat.

Coral reefs are often compared to cities, an analogy that captures both the variety and the density of life they support. The number of species that can be found on a small patch of healthy reef is probably greater than can be encountered in a similar amount of space anywhere else on Earth, including the Amazon rain forest. Researchers who once picked apart a single coral colony counted more than eight thousand burrowing creatures belonging to more than two hundred species. Using more sophisticated genetic-sequencing techniques, scientists recently looked to see how many species of crustaceans alone they could find. In one square metre at the northern end of the Great Barrier Reef, they came up with more than two hundred species—mostly crabs and shrimp—and in a similar-size stretch, at the southern end, they identified almost two hundred and thirty species. Extrapolating beyond crustaceans to fish and snails and sponges and octopuses and squid and sea squirts and on through the phyla, scientists estimate that reefs are home to at least a million and possibly as many as nine million species.

This diversity is even more remarkable in light of what might, to extend the urban metaphor, be called reefs’ environs. Tropical seas tend to be low in nutrients like nitrogen and phosphorus. Since most forms of life require nitrogen and phosphorus, tropical seas also tend to be barren; this explains why they’re often so marvellously clear. Ever since Darwin, scientists have been puzzled by how reefs support such richness under nutrient-poor conditions. The best explanation anyone has come up with is that on reefs—and here the metropolitan analogy starts to break down—all the residents enthusiastically recycle.

Because so much is at stake, Gates argues, the super-coral project is imperative. “I don’t really care about the ‘me’ in this,” she said one day over lunch in a strip mall in Kaneohe, the town closest to Moku o Lo‘e. “I care about what happens to corals. If I can do something that will help preserve them and perpetuate them into the future, I’m going to do everything I can.”

But scale is also what makes many other researchers leery of the project. Terry Hughes, the director of the Australian Research Council’s Centre of Excellence for Coral Reef Studies, once did a study of conventional coral-restoration projects, which involve raising coral colonies in tanks and transplanting them onto damaged reefs.

“I scoured the literature for any examples I could find,” he told me. He found some two hundred and fifty projects, which collectively cost a quarter of a billion dollars. The total area that was covered by the projects was just two and a half acres, or roughly two football fields.

“So we can call that the ‘restored area,’ though there are issues around that, because often the corals in these projects die,” Hughes went on. “When you consider just the Great Barrier Reef, which is a tiny fraction of the world’s reefs, it has the area of Finland. So going from a test tube or an aquarium to millions of football fields is hugely expensive, obviously.” The sort of scaling up that would be required would mean corals could no longer be transplanted; they’d have to be dispersed in another way, perhaps as embryos. (Coral embryos form larvae that drift around for a while before settling.)

“If you put corals—super corals—out in Kaneohe Bay, it would take probably thousands of years for them to spread naturally from Hawaii, which is an isolated archipelago,” Hughes said. “So you’d have to have some mechanism—aerial spraying from helicopters or something—to spread them around the Pacific. I don’t know how you would get to that next step.” At the time I spoke to Hughes, it was late summer in Australia, and the northern part of the Great Barrier Reef was suffering from the worst bleaching that observers had ever seen.

Ken Caldeira is a researcher at the Carnegie Institution for Science, at Stanford University, who studies ocean acidification. He noted that reef-building corals, from the order Scleractinia, have been around at least since the mid-Triassic. Yet reefs remain confined to those relatively few spots on the planet where conditions suit them just right.

“I find it implausible that we’re going to succeed in doing in a couple of years what evolution hasn’t succeeded at over the past few hundred million years,” Caldeira observed. “There’s this idea that there should be some easy techno-fix, if only we could be creative enough to find it. I guess I just don’t think that’s true.”

Half a hemisphere away from Moku o Lo‘e, the American Chestnut Research and Restoration Project operates out of several labs and a greenhouse in Syracuse, New York. It, too, might be described as an effort at assisted evolution, only with a much more radical assist. The project’s aim is not to breed up a tougher tree but to create one through genetic engineering.

William Powell, a professor at the State University of New York’s College of Environmental Science and Forestry, founded the chestnut project with a colleague, Charles Maynard, and now they co-direct it. Powell is fifty-nine, with gray hair, dark eyebrows, and a boyish earnestness.

“Not only was baby’s crib likely made of chestnut, but chances were, so was the old man’s coffin,” a plant pathologist named George Hepting wrote.

Then, in 1904, the chief forester at the New York Zoological Park—now the Bronx Zoo—noticed that some of the chestnut trees in the park were ailing. The following year, so many trees were turning brown that the forester appealed for help to the U.S. Department of Agriculture and the New York Botanical Garden. Within five years, chestnut trees from Maryland to Connecticut were dying. The culprit was identified as a fungus, which had been imported from Asia, probably on Japanese chestnut trees, Castanea crenata. (Japanese chestnuts, which co-evolved with the fungus, find it only a minor irritant.) By the nineteen-forties, some four billion American chestnut trees had been wiped out. American chestnuts can resprout from the root collar; today, pretty much the only examples that still exist in the woods are small, spindly trees that have sprung up in this way.

“They will grow for a while and then get killed down to the ground again,” Powell told me. “So they’re kind of in what I call a Sisyphean cycle.” (The trees known as horse chestnuts, which can be found in many parks and gardens, are not, technically, chestnuts at all; they are members of a different family.)

Efforts to save Castanea dentata began almost as soon as the blight swept through. The first attempts involved hybridizing American chestnuts with other chestnut species. Then came zapping chestnuts with gamma radiation, in the hopes of producing a beneficial mutation. Next was a scheme to weaken the fungus by using a virus. These efforts produced thousands upon thousands of trees, all of which either succumbed to the blight or were so different from the American chestnut that they could hardly be said to be reviving it.

Powell attended graduate school in the nineteen-eighties, around the same time as Gates, and, like her, he was fascinated by molecular biology. When he got a job at the forestry school, in 1990, he started thinking about how new molecular techniques could be used to help the chestnut. Powell had studied how the fungus attacked the tree, and he knew that its key weapon was oxalic acid. (Many foods contain oxalic acid—it’s what gives spinach its bitter taste—but in high doses it’s also fatal to humans.) One day, he was leafing through abstracts of recent scientific papers when a finding popped out at him. Someone had inserted into a tomato plant a gene that produces oxalate oxidase, or OxO, an enzyme that breaks down oxalic acid.

“I thought, Wow, that would disarm the fungus,” he recalled.

Years of experimentation ensued. The gene can be found in many grain crops; Powell and his research team chose a version from wheat. First they inserted the wheat gene into poplar trees, because poplars are easy to work with. Then they had to figure out how to work with chestnut tissue, because no one had really done that before. Meanwhile, the gene couldn’t just be inserted on its own; it needed a “promoter,” which is a sort of genetic on-off switch. The first promoter Powell tried didn’t work. The trees—really tiny seedlings—didn’t produce enough OxO to fight off the fungus. “They just died more slowly,” Powell told me. The second promoter was also a dud. Finally, after two and a half decades, Powell succeeded in getting all the pieces in place. The result is a chestnut that is blight-resistant and—except for the presence of one wheat gene and one so-called “marker gene”—identical to the original Castanea dentata.

“I always say that it’s 99.9997-per-cent American chestnut,” he said.

In another plot, surrounded by an eight-foot fence, were a few dozen transgenic trees. These had smooth, unblemished bark, which reminded me of snakeskin. The tallest was about ten feet high and about six inches in diameter. It was a chilly day in March, and all the branches were bare. Powell explained that the fence was mostly to keep out deer, but also to discourage anti-G.M.O. protesters. He told me that I ought to come back in late spring, when the trees would be in bloom. Chestnuts produce streamer-like catkins, covered in tiny white flowers. “People used to say it was like snow in June,” he said.

Before any transgenic trees can be planted outside an experimental plot, they have to be approved by three federal agencies: the Department of Agriculture, the Food and Drug Administration, and the Environmental Protection Agency. Powell is planning to request approval later this year. This will initiate a review process that could take up to five years. Once approval is granted—assuming that it is—Powell wants to produce ten thousand trees that can be made available to the public. If all these trees get planted and survive, they will represent .00025 per cent of the chestnuts that grew in America before the blight.

“This is a century-long project,” Powell said. “That’s why I tell people, ‘You’ve got to get your children, you’ve got to get your grandchildren involved in this.’ ”

As the world warms, and the oceans acidify, and species are reshuffled from one continent to another, it’s increasingly difficult to say what would count as conservation. In his most recent book, “Half-Earth,” the biologist E. O. Wilson argues that the best hope for the planet’s remaining species lies in leaving them alone. Even today, there are vast regions where, Wilson writes, “natural processes unfold in the absence of deliberate human intervention.” (The Amazon Basin is one such region; the Serengeti is another.) We ought to allow these processes to continue, Wilson argues. To this end, he recommends setting aside fifty per cent of the planet’s surface as reserves.

“Give the rest of Earth’s life a chance,” he pleads.

Those scientists who recommend this sort of hands-off approach—and there are many of them—stress the limits of what science can accomplish. Just because you can break an egg doesn’t mean you can put it back together. They argue that even the best-intentioned intervention can do more harm than good. People may read about a project like Gates’s or Powell’s and take exactly the wrong lesson from it.

“There’s a lot of psychology here,” Terry Hughes told me. “There is a danger of thinking we’ve found the technological solution, so therefore we can keep damaging reefs, because we can always fix them in the future.

“In terms of protecting ecosystems like coral reefs or rain forests, prevention is always better than cure,” he added.

Advocates for techniques like assisted evolution and genetic engineering argue that the moment for being hands off has passed. Humans have already so violently altered the world that without “deliberate intervention” the future holds only loss and more loss.

“There’s just too many people right now,” Powell told me. “I always say, ‘We need a full toolbox of methods to keep our forests healthy.’ And we shouldn’t limit it by saying, ‘Well, you can do this method but you can’t do that method.’

“You have emerald ash borer going through right now,” he went on. (The borer, another import from Asia, is killing ash trees from Colorado to New Hampshire.) “Should we just leave the ash trees and say, O.K., they’re gone? Woolly adelgid is killing the hemlocks. If we lose all the hemlocks, do we just say, O.K., that’s gone? There’s what’s called thousand-cankers disease that’s spreading on walnuts right now. Is that the kind of attitude we should have? We have all these challenges out there, and the question is: Should we just let the trees die out? And to me that’s not an option.”

When I was in Hawaii, I found myself wavering. I would listen to Gates and agree with her: there’s no going back. Then I would get on the little ferry and try to picture the super-coral project moving forward. My head would start to ache. Corals are slow to reach sexual maturity, and, when they do, most spawn only once a year. Crossbreeding requires many generations, and in that time—however long it may be—the seas will have grown that much warmer and more acidified. Well over a thousand species of Scleractinia have been identified, and probably lots more await discovery. To save reefs is a project akin to saving forests; one species of super coral wouldn’t be enough. You’d need to breed hundreds of them. And, even if this could be accomplished, how would you get billions and billions of polyps settled in the ocean?

“There are many, many unknowns,” she went on. “And people are very quick to criticize based on ‘But what happens if this doesn’t work and what happens if this doesn’t work?’ And I say, ‘Well, I don’t know now, but I know I’ll know more when I get there.’ And I feel that we’re at this point where we need to throw caution to the wind and just try.” ♦