On a recent July night in the water near a tiny island off the coast of Oahu, a group of divers watched through the glow of red headlamps as corals spawned, the coral equivalent of group sex. Tiny eggs and sperm streamed upward like champagne bubbles, and the divers–biologists from the Gates Coral Lab at the Hawai’i Institute of Marine Biology–used nets to capture some of them to bring back to the lab.

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The goal: to cross-breed species that survived recent coral bleaching–a heat-driven process that causes the coral to expel its symbiotic algae, turning it white and eventually killing it–to create offspring that have a better chance in the hotter, more acidic ocean of the future. It’s one example of so-called assisted evolution–an attempt to help species adapt to a changing environment more quickly than they are likely to through natural selection. Thousands of miles away, in British Columbia, researchers are studying the genetics of pine trees so breeders can breed trees that better resist a particular disease that is increasing with climate change. With thousands of other plants and animals at risk of extinction–in the Amazon alone, around 34,000 plants may be extinct by the end of the century if the planet warms two degrees–it’s possible that assisted evolution is an approach that may eventually be used more widely. “I think assisted evolution will allow us to buy some time until the world addresses greenhouse gases in the atmosphere and climate warming,” says Madeleine van Oppen, a University of Melbourne professor helping lead the research at the Australian Institute of Marine Science, where researchers use a “sea simulator” that precisely mimics the conditions of the changing ocean to test which coral are hardiest. Corals, tiny organisms that live in colonies to build reefs, face multiple threats, from overfishing to polluted water, but are particularly at risk from greenhouse gas emissions. Roughly 40% of human-caused CO2 emissions, or more than 170 billion metric tons so far, has ended up in the ocean, making it more acidic. Acidity can both make it hard for coral to build reefs and can make reefs dissolve. As the water gets hotter because of climate change, that can kill coral. Some reefs may also not grow as quickly as the sea level is rising. The loss of coral reefs would have a staggering impact. Even though reefs only make up 1% of the ocean environment, they’re home to a quarter of marine species. That includes thousands of species of fish, a critical source of food for humans. In countries like Madagascar and Indonesia and Honduras, tourism from coral reefs is an important part of the economy. Reefs also provide billions of dollars worth of flood protection from storms. “I’m not even sure, with the projections, that the majority of the world’s reefs can survive the 2050 window without some help,” says Ruth Gates, director of the Hawai’i Institute of Marine Biology, who is leading the research to identify and breed “super corals” at the Hawaiian lab. “And that scares the hell out of me, to be honest with you. I’ve been working on them since the 1980s, and to think that they, as a system, could die in my lifetime is really mind-blowing.”

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Huge sections of the Great Barrier Reef, which stretches around 1,400 miles, are now dead, and mass bleaching events around the world are now five times more likely than they were 40 years ago. The more frequently the coral bleaches, the less likely it is to recover. Though coral is know to be able to evolve to survive pressures like higher temperatures, it’s not evolving quickly enough in the face of the rapidly changing climate. In 2016, bleaching hit more than 90% of the Great Barrier Reef. “The fact that we have lost so much coral over the past few decades, and particularly during the most recent heat waves [in] 2014 to 2017, testifies . . . that natural rates of adaptation and acclimatization are too slow to keep pace with climate change,” says van Oppen. Breeding super-strong coral could help, and gene-edited corals could potentially help as well. Selective breeding, of course, is something that has been done for thousands of years in agriculture. More recently, seed companies are increasingly focused on trying to make crops–either through breeding or gene editing–that are more resistant to drought or heat waves from climate change. “In some ways, I don’t think it’s particularly new to think about doing it for other things in our natural environment that are important for human health and survival,” says Alex Dehgan, CEO and cofounder of Conservation X Labs, a startup that works on tech for conservation. “And I think our corals might be one of those things, as we’re increasingly dependent on fisheries for protein.” On one end of the spectrum, “assisted evolution” might also simply mean helping organisms move from one place to another. In British Columbia, for example, forests that have been logged or burned in wildfires are beginning to be replanted with trees that normally grow further south, to help prepare for a warmer future. Finland and Sweden are working on similar projects, often called “assisted gene flow.” While it’s not necessarily easy to change the government guidelines for planting trees, it may get support more easily than planting trees that have been crossbred or genetically edited. It may also be easier to accomplish scientifically. “One of the things about climate adaptation is that it is very complex genetically because there’s a bunch of traits, and each of those traits is controlled by probably hundreds of genes,” says Sally Aitken, a professor of forest and conservation sciences at the University of British Columbia who studies assisted gene flow. “And so in some ways that assisted gene flow is easier and quicker than the breeding.” (Aitken is also working on a genetic research project to help tree breeders grow trees that can resist a particular blight that is more common in warmer, wetter weather.)

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In coral reefs, too, some coral could potentially be moved from warmer to cooler waters. In the Great Barrier Reef, for example, if corals from warmer water are moved to cooler water and cross-breed, they may pass on some of their ability to withstand warm temperatures to their offspring. That may not work universally–there are hundreds of different species of coral, and some coral that have adapted to warmer waters may not do well with temperature fluctuations in new locations. Breeding in a lab, or gene editing through tools like CRISPR, could also be useful. Some researchers are cautious about the potential. “My thought about this is that the research is really important to do and because we need to explore every avenue that we have to maintain healthy reefs,” says James Guest, a researcher at Newcastle University who is also studying and breeding coral. “On the other hand, we shouldn’t get too carried away because these things are really difficult to do and really expensive–and it hasn’t been shown to work yet.” The work is also controversial. “I think that we’ve been a little naive about the environmental impacts of genetic modification,” says Mark Spalding, a senior marine scientist at The Nature Conservancy. “In reality, it is not benign and there could easily be repercussions that we can’t predict from the release of GM corals and symbionts.” Because coral reefs form a structure that is home to thousands of species, changing the coral could potentially change the community of plants and animals that live there. More significant changes, such as editing genes rather than simply moving coral from one part of its range to another, could potentially have unknown ripple effects. Unintended consequences are, by definition, hard to predict. But even without attempts at restoration, reefs are already changing–and already affecting the ecosystem they support. Another risk of “assisted evolution” is that the diversity of corals would likely shrink. But diversity is shrinking even more dramatically because of climate change. “I hate to say it, but climate change is doing the most obscene genetic narrowing experiment that has ever been done,” says Gates. “So perhaps we need to step back a little bit and think about the relative risk . . . One thing is for sure: If we do nothing, we will lose a vast majority of the corals on the planet. And so that’s always the context of the work that we do.” Dehgan, from Conservation X Labs, argues that it may be time to rethink the precautionary principle–the idea that if a new product or technology poses an unknown risk to human health or the environment, it’s better not to adopt it. “We do have sufficient information of the other alternative, which is a clear pathway to the loss of most of our plants and animals around the world,” says Dehgan. “Given that loss, we need to improve the speed and efficacy of the solutions that are at hand. And that means greater experimentation rather than greater reservedness. So I think in some ways, things like the precautionary principle have actually run their course.”

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In theory, assisted evolution could be used in many other ways to help endangered species–animals dying from a particular disease exacerbated by climate change, for example, could potentially be bred to resist that disease. In some ways, it might not be that much more drastic than some of the other current attempts to ward off the so-called “sixth extinction” underway because of humans. Biologists are already using in-vitro fertilization to try to save the northern white rhino, for example. For coral, the work takes several steps. In one process in the Florida Keys, Mote Marine Lab is propagating stronger coral by finding species that have survived a bleaching event, bringing some pieces of those corals to a coral nursery on land, and turning them into microfragments–thousands of tiny pieces that each have genetic resilience to warmer waters. (At least one startup is using the same approach to quickly farm coral to plant in reefs.) In a controlled environment in tanks, the coral grows very quickly. Once they reach a certain size, they can be transplanted into the ocean–and even if some don’t survive, because there are thousands, some will–and they can reproduce with other corals to spread their more resilient genes. It’s challenging, of course, to do at a massive scale, and the same is true of coral that has been bred or gene edited: How do you transplant millions of corals into reefs? “With Mote Labs, we already know that the bottleneck is not going to be how fast we can grow corals on land, but the bottleneck is going to be the effort that it would take to plant them in the ocean,” says Luis Solórzano, the executive director of the Caribbean Program at The Nature Conservancy, which is working with Mote Labs. “We are looking into alternatives like artificial intelligence-driven robots that can do this 24 hours a day, seven days a week. With divers, it’s going to be impossible. It would be armies of divers diving all the time to be able to do this. It has to be mechanized.” Gates is moving forward as quickly as possible, adopting new tools like sophisticated cameras that can identify the best-performing corals on a reef so that they can be studied and replicated. “I think we’re in this absolute sweet spot of deep need for action quickly and then emerging technology is enabling that action at a scale that probably has never been possible before,” she says. In the artificial ocean at Biosphere 2, the research lab in Arizona that was built to attempt to replicate conditions on Earth (the original Mars-like experiment ended in 1994 when the people living inside couldn’t maintain the systems needed for survival), Gates plans to construct a climate-adapted reef, stocked with coral bred to survive the future. Soon, she and other researchers hope to begin propagating coral stock at a scale large enough to begin making a difference in the ocean. It will cost “many millions,” she says. “But, of course, that is all relative to an ecosystem that delivers billions in human services. Pretty good return on investment, I would say.” Some researchers say that it could take time to begin to implement this work in the ocean. “Many of these approaches are completely new,” says Line Bay, a researcher at the Australian Institute of Marine Science. “They haven’t ever been tested before, and so the lead time to do the research, to do the lab trials, the field trials to demonstrate their benefit, their risks and also what they will cost to implement will take one to two decades. So that’s why we’re getting together now to really talk about it and get started now while we still have options and we still have time to do this work properly.” The Australian researchers will need to get government permits before doing field tests in the Great Barrier Reef.

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Gates argues that work needs to happen faster because of the urgency of climate change. “If we want to save coral reefs, we have to change the way we translate science into action,” she says. “It’s as simple as that. We have to accelerate that time line and we have to work with the right communities to do that.” None of this means, of course, that we can stop reducing the carbon emissions that have created the problem. “These things are not competing with the mitigation of CO2,” she says. “This is just the second part of a picture that we have to put together. We have to [reduce] greenhouse gas emissions. And we have to adapt the corals themselves.”