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    A stunning visualization of Alaska’s Yukon Delta shows a land in transition

    The westward journey of the mighty Yukon River takes it from its headwaters in Canada’s British Columbia straight across Alaska. The river has many stories to tell, of generations of Indigenous people hunting on its banks and fishing in its waters, of paddle-wheeled boats and gold panning and pipelines.

    Where it meets the Bering Sea, the river fans out into an intricate delta resembling cauliflower lobes of river channels and ponds. The delta has a story to tell, too — that of an increasingly green Arctic.

    A composite image of the delta’s northern lobe, taken May 29 by the U.S. Geological Survey’s Landsat 8 satellite, shows willow shrublands lining river channels as they wind toward the sea. Farther inland, tussock grasses carpet the tundra. Grasslike sedge meadows populate low-lying wetlands, punctuated by ponds left behind by springtime floods along the riverbanks from snow and ice that have melted upstream.

    In southern Alaska, such as in the Kenai Peninsula, the Arctic has been getting noticeably greener since the 1980s, as global temperatures climb (SN: 4/11/19). Researchers observed this change using satellite measurements of red and near-infrared light reflected off the vegetation. Now, analyses of changing vegetation in the Yukon Delta and nearby Kuskokwim Delta show that more northern areas are getting greener too, researchers report June 1 in Earth Interactions.

    The increasing prevalence of tall willows, an important moose habitat, is one sign of these changes in the delta. Moose populations, too, are on the rise. But for the Yukon and other Arctic deltas — where higher floodwaters due to climate change are likely to deposit thicker sediment piles, supporting more greenery — many more changes are likely to come as the planet warms.  More

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    How intricate Venus’s-flower-baskets manipulate the flow of seawater

    A Venus’s-flower-basket isn’t all show. This stunning deep-sea sponge can also alter the flow of seawater in surprising ways.

    A lacy, barrel-shaped chamber forms the sponge’s glassy skeleton. Flow simulations reveal how this intricate structure alters the way water moves around and through the sponge, helping it endure unforgiving ocean currents and perhaps feed and reproduce, researchers report online July 21 in Nature.

    Previous studies have found that the gridlike construction of a Venus’s-flower-basket (Euplectella aspergillum) is strong and flexible. “But no one has ever tried to see if these beautiful structures have fluid-dynamic properties,” says mechanical engineer Giacomo Falcucci of Tor Vergata University of Rome.

    Harnessing supercomputers, Falcucci and colleagues simulated how water flows around and through the sponge’s body, with and without different skeletal components such as the sponge’s myriad pores. If the sponge were a solid cylinder, water flowing past would form a turbulent wake immediately downstream that could jostle the creature, Falcucci says. Instead water flows through and around the highly porous Venus’s-flower-basket and forms a gentle zone of water that flanks the sponge and displaces turbulence downstream, the team found. That way, the sponge’s body endures less stress.

    Ridges that spiral around the outside of the sponge’s skeleton also somehow cause water to slow and swirl inside the structure, the simulations showed. As a result, food and reproductive cells that drift into the sponge would become trapped for up to twice as long as in the same sponge without ridges. That lingering could help the filter feeders catch more plankton. And because Venus’s-flower-baskets can reproduce sexually, it could also enhance the chances that free-floating sperm encounter eggs, the researchers say.

    It’s amazing that such beauty could be so functional, Falcucci says. The sponge’s flow-altering abilities, he says, might help inspire taller, more wind-resistant skyscrapers.

    This simulation shows how water flows around and through a Venus’s-flower-basket (gray). Ridges that spiral across the outside of the sponge cause water inside to somehow slow and swirl, forming particle-trapping vortices. And the sponge’s shape creates a gentle zone of slower water that forms immediately downstream, buffering the creature against turbulence. Vertical cross sections contrast the flow activity of the calm zone (nearer the sponge) and the turbulent zone (downstream).G. Falcucci et al/Nature 2021 More

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    Climate change may be leading to overcounts of endangered bonobos

    Climate change is interfering with how researchers count bonobos, possibly leading to gross overestimates of the endangered apes, a new study suggests.

    Like other great apes, bonobos build elevated nests out of tree branches and foliage to sleep in. Counts of these nests can be used to estimate numbers of bonobos — as long as researchers have a good idea of how long a nest sticks around before it’s broken down by the environment, what’s known as the nest decay time.

    New data on rainfall and bonobo nests show that the nests are persisting longer in the forests in Congo, from roughly 87 days, on average, in 2003–2007 to about 107 days in 2016–2018, largely as a result of declining precipitation. This increase in nests’ decay time could be dramatically skewing population counts of the endangered apes and imperiling conservation efforts, researchers report June 30 in PLOS ONE.

    “Imagine going in that forest … you count nests, but each single nest is around longer than it used to be 15 years ago, which means that you think that there are more bonobos than there really are,” says Barbara Fruth, a behavioral ecologist at the Max Planck Institute of Animal Behavior in Konstanz, Germany.

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    Lowland tropical forests, south of the Congo River in Africa, are the only place in the world where bonobos (Pan paniscus) still live in the wild (SN: 3/18/21). Estimates suggest that there are at least 15,000 to 20,000 bonobos there. But there could be as many as 50,000 individuals. “The area of potential distribution is rather big, but there have been very few surveys,” Fruth says.

    From 2003 to 2007, and then again from 2016 to 2018, Fruth and colleagues followed wild bonobos in Congo’s LuiKotale rain forest, monitoring 1,511 nests. “The idea is that you follow [the bonobos] always,” says Mattia Bessone, a wildlife researcher at the Liverpool John Moores University in England. “You need to be up early in the morning so that you can be at the spot where the bonobos have nested, in time for them to wake up, and then you follow them till they nest again.”

    In doing so, day after day, Fruth, Bessone and colleagues were first able to understand how many nests a bonobo builds in a day, what’s known as the nest construction rate. “It’s not necessarily one because sometimes bonobos build day nests,” Bessone says. On average, each bonobo builds 1.3 nests per day, the team found.

    Tracking how long these nests stuck around revealed that the structures were lasting an average of 19 days longer in 2016–2018 than in 2003–2007. The researchers also compiled fifteen years of climate data for LuiKotale, which showed a decrease in average rainfall from 2003 to 2018. That change in rain is linked to climate change, the researchers say, and helps explain why nests have become more resilient.

    These images show bonobo nests at different stages of decay. Knowing the time it takes for a nest to decay is crucial for estimating accurate bonobo numbers.© B. Fruth/MPI of Animal Behavior

    By counting the numbers of nests and then dividing that number by the product of the average nest decay time and nest construction rate, scientists can get an estimate of the number of bonobos in a region. But if researchers are using outdated, shorter nest decay times, those estimates could be severely off, overestimating bonobo counts by up to 50 percent, Bessone says.

    “The results are not surprising but also highlight how indirect (and therefore prone to errors) our methods of density estimates of many species are,” Martin Surbeck, a behavioral ecologist at Harvard University, wrote in an e-mail.

    Technologies such as camera traps can be used to directly count animals instead of using proxies like nests and are the way forward for animal population studies, researchers say. But until those methods become more common, nest counts remain vital for scientists’ understanding of bonobo numbers.

    This phenomenon is probably not limited to bonobos. All great apes build nests, and nest counts are used to estimate those animals’ numbers too. So, the researchers say, the new results could have implications for the conservation of primates far beyond bonobos. More

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    Hurricanes may not be becoming more frequent, but they’re still more dangerous

    Climate change is helping Atlantic hurricanes pack more of a punch, making them rainier, intensifying them faster and helping the storms linger longer even after landfall. But a new statistical analysis of historical records and satellite data suggests that there aren’t actually more Atlantic hurricanes now than there were roughly 150 years ago, researchers report July 13 in Nature Communications.

    The record-breaking number of Atlantic hurricanes in 2020, a whopping 30 named storms, led to intense speculation over whether and how climate change was involved (SN: 12/21/20). It’s a question that scientists continue to grapple with, says Gabriel Vecchi, a climate scientist at Princeton University. “What is the impact of global warming — past impact and also our future impact — on the number and intensity of hurricanes and tropical storms?”

    Satellite records over the last 30 years allow us to say “with little ambiguity how many hurricanes, and how many major hurricanes [Category 3 and above] there were each year,” Vecchi says. Those data clearly show that the number, intensity and speed of intensification of hurricanes has increased over that time span.

    But “there are a lot of things that have happened over the last 30 years” that can influence that trend, he adds. “Global warming is one of them.” Decreasing aerosol pollution is another (SN: 11/21/19). The amount of soot and sulfate particles and dust over the Atlantic Ocean was much higher in the mid-20th century than now; by blocking and scattering sunlight, those particles temporarily cooled the planet enough to counteract greenhouse gas warming. That cooling is also thought to have helped temporarily suppress hurricane activity in the Atlantic.  

    To get a longer-term perspective on trends in Atlantic storms, Vecchi and colleagues examined a dataset of hurricane observations from the U.S. National Oceanic and Atmospheric Administration that stretches from 1851 to 2019. It includes old-school observations by unlucky souls who directly observed the tempests as well as remote sensing data from the modern satellite era.

    How to directly compare those different types of observations to get an accurate trend was a challenge. Satellites, for example, can see every storm, but earlier observations will count only the storms that people directly experienced. So the researchers took a probabilistic approach to fill in likely gaps in the older record, assuming, for example, that modern storm tracks are representative of pre-satellite storm tracks to account for storms that would have stayed out at sea and unseen. The team found no clear increase in the number of storms in the Atlantic over that 168-year time frame. One possible reason for this, the researchers say, is a rebound from the aerosol pollution–induced lull in storms that may be obscuring some of the greenhouse gas signal in the data.  

    More surprisingly — even to Vecchi, he says — the data also seem to show no significant increase in hurricane intensity over that time. That’s despite “scientific consistency between theories and models indicating that the typical intensity of hurricanes is more likely to increase as the planet warms,” Vecchi says. But this conclusion is heavily caveated — and the study also doesn’t provide evidence against the hypothesis that global warming “has acted and will act to intensify hurricane activity,” he adds.

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    Climate scientists were already familiar with the possibility that storm frequency might not have increased much in the last 150 or so years — or over much longer timescales. The link between number of storms and warming has long been uncertain, as the changing climate also produces complex shifts in atmospheric patterns that could take the hurricane trend in either direction. The Intergovernmental Panel on Climate Change noted in a 2012 report that there is “low confidence” that tropical cyclone activity has increased in the long term.

    Geologic evidence of Atlantic storm frequency, which can go back over 1,000 years, also suggests that hurricane frequency does tend to wax and wane every few decades, says Elizabeth Wallace, a paleotempestologist at Rice University in Houston (SN: 10/22/17).

    Wallace hunts for hurricane records in deep underwater caverns called blue holes: As a storm passes over an island beach or the barely submerged shallows, winds and waves pick up sand that then can get dumped into these caverns, forming telltale sediment deposits. Her data, she says, also suggest that “the past 150 years hasn’t been exceptional [in storm frequency], compared to the past.”

    But, Wallace notes, these deposits don’t reveal anything about whether climate change is producing more intense hurricanes. And modern observational data on changes in hurricane intensity is muddled by its own uncertainties, particularly the fact that the satellite record just isn’t that long. Still, “I liked that the study says it doesn’t necessarily provide evidence against the hypothesis” that higher sea-surface temperatures would increase hurricane intensity by adding more energy to the storm, she says.

    Kerry Emanuel, an atmospheric scientist at MIT, says the idea that storm numbers haven’t increased isn’t surprising, given the longstanding uncertainty over how global warming might alter that. But “one reservation I have about the new paper is the implication that no significant trends in Atlantic hurricane metrics [going back to 1851] implies no effect of global warming on these storms,” he says. Looking for such a long-term trend isn’t actually that meaningful, he says, as scientists wouldn’t expect to see any global warming-related hurricane trends become apparent until about the 1970s anyway, as warming has ramped up.

    Regardless of whether there are more of these storms, there’s no question that modern hurricanes have become more deadly in many ways, Vecchi says. There’s evidence that global warming has already been increasing the amount of rain from some storms, such as Hurricane Harvey in 2017, which led to widespread, devastating flooding (SN: 9/28/18). And, Vecchi says, “sea level will rise over the coming century … so [increasing] storm surge is one big hazard from hurricanes.” More

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    The first step in using trees to slow climate change: Protect the trees we have

    Between a death and a burial was hardly the best time to show up in a remote village in Madagascar to make a pitch for forest protection. Bad timing, however, turned out to be the easy problem.

    This forest was the first one that botanist Armand Randrianasolo had tried to protect. He’s the first native of Madagascar to become a Ph.D. taxonomist at Missouri Botanical Garden, or MBG, in St. Louis. So he was picked to join a 2002 scouting trip to choose a conservation site.

    Other groups had already come into the country and protected swaths of green, focusing on “big forests; big, big, big!” Randrianasolo says. Preferably forests with lots of big-eyed, fluffy lemurs to tug heartstrings elsewhere in the world.

    The Missouri group, however, planned to go small and to focus on the island’s plants, legendary among botanists but less likely to be loved as a stuffed cuddly. The team zeroed in on fragments of humid forest that thrive on sand along the eastern coast. “Nobody was working on it,” he says.

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    As the people of the Agnalazaha forest were mourning a member of their close-knit community, Randrianasolo decided to pay his respects: “I wanted to show that I’m still Malagasy,” he says. He had grown up in a seaside community to the north.

    The village was filling up with visiting relatives and acquaintances, a great chance to talk with many people in the region. The deputy mayor conceded that after a morning visit to the bereaved, Randrianasolo and MBG’s Chris Birkinshaw could speak in the afternoon with anyone wishing to gather at the roofed marketplace.

    Courtesy of the staff of the Missouri Botanical Garden, St. Louis and Madagascar

    Courtesy of the staff of the Missouri Botanical Garden, St. Louis and Madagascar

    Courtesy of the staff of the Missouri Botanical Garden, St. Louis and Madagascar

    Conserving natural forests is a double win for trapping carbon and saving rich biodiversity. Forests matter to humans (with a Treculia fruit), Phromnia planthoppers and mouse lemurs.

    The two scientists didn’t get the reception they’d hoped for. Their pitch to help the villagers conserve their forest while still serving people’s needs met protests from the crowd: “You’re lying!”

    The community was still upset about a different forest that outside conservationists had protected. The villagers had assumed they would still be able to take trees for lumber, harvest their medicinal plants or sell other bits from the forest during cash emergencies. They were wrong. That place was now off-limits. People caught doing any of the normal things a forest community does would be considered poachers. When MBG proposed conserving yet more land, residents weren’t about to get tricked again. “This is the only forest we have left,” they told the scientists.

    Finding some way out of such clashes to save existing forests has become crucial for fighting climate change. Between 2001 and 2019, the planet’s forests trapped an estimated 7.6 billion metric tons of carbon dioxide a year, an international team reported in Nature Climate Change in March. That rough accounting suggests trees may capture about one and a half times the annual emissions of the United States, one of the largest global emitters.

    Planting trees by the millions and trillions is basking in round-the-world enthusiasm right now. Yet saving the forests we already have ranks higher in priority and in payoff, say a variety of scientists.

    How to preserve forests may be a harder question than why. Success takes strong legal protections with full government support. It also takes a village, literally. A forest’s most intimate neighbors must wholeheartedly want it saved, one generation after another. That theme repeats in places as different as rural Madagascar and suburban New Jersey.

    Overlooked and underprotected

    First a word about trees themselves. Of course, trees capture carbon and fight climate change. But trees are much more than useful wooden objects that happen to be leafy, self-manufacturing and great shade for picnics.

    “Plant blindness,” as it has been called, reduces trees and other photosynthetic organisms to background, lamented botanist Sandra Knapp in a 2019 article in the journal Plants, People, Planet. For instance, show people a picture with a squirrel in a forest. They’ll likely say something like “cute squirrel.” Not “nice-size beech tree, and is that a young black oak with a cute squirrel on it?”

    This tunnel vision also excludes invertebrates, argues Knapp, of the Natural History Museum in London, complicating efforts to save nature. These half-seen forests, natural plus human-planted, now cover close to a third of the planet’s land, according to the 2020 version of The State of the World’s Forests report from the United Nation’s Food and Agriculture Organization. Yet a calculation based on the report’s numbers says that over the last 10 years, net tree cover vanished at an average rate of about 12,990 hectares — a bit more than the area of San Francisco — every day.

    This is an improvement over the previous decades, the report notes. In the 1990s, deforestation, on average, destroyed about 1.75 San Francisco equivalents of forest every day.

    Branches of a Dracaena cinnabari dragon’s blood tree from Yemen ooze red sap and repeatedly bifurcate in even Y-splits.BORIS KHVOSTICHENKO/WIKIMEDIA COMMONS (CC BY-SA 4.0)

    Trees were the planet’s skyscrapers, many rising to great heights, hundreds of millions of years before humans began piling stone upon stone to build their own. Trees reach their stature by growing and then killing their innermost core of tissue. The still-living outer rim of the tree uses its ever-increasing inner ghost architecture as plumbing pipes that can function as long as several human lifetimes. And tree sex lives, oh my. Plants invented “steamy but not touchy” long before the Victorian novel — much flowering, perfuming and maybe green yearning, all without direct contact of reproductive organs. Just a dusting of pollen wafted on a breeze or delivered by a bee.

    To achieve the all-important goal of cutting global emissions, saving the natural forests already in the ground must be a priority, 14 scientists from around the world wrote in the April Global Change Biology. “Protect existing forests first,” coauthor Kate Hardwick of Kew Gardens in London said during a virtual conference on reforestation in February. That priority also gives the planet’s magnificent biodiversity a better chance at surviving. Trees can store a lot of carbon in racing to the sky. And size and age matter because trees add carbon over so much of their architecture, says ecologist David Mildrexler with Eastern Oregon Legacy Lands at the Wallowology Natural History Discovery Center in Joseph. Trees don’t just start new growth at twigs tipped with unfurling baby leaves. Inside the branches, the trunk and big roots, an actively growing sheath surrounds the inner ghost plumbing. Each season, this whole sheath adds a layer of carbon-capturing tissue from root to crown.

    “Imagine you’re standing in front of a really big tree — one that’s so big you can’t even wrap your arms all the way around, and you look up the trunk,” Mildrexler says. Compare that sky-touching vision to the area covered in a year’s growth of some sapling, maybe three fingers thick and human height. “The difference is, of course, just huge,” he says.

    Big trees may not be common, but they make an outsize difference in trapping carbon, Mildrexler and colleagues have found. In six Pacific Northwest national forests, only about 3 percent of all the trees in the study, including ponderosa pines, western larches and three other major species, reached full-arm-hug size (at least 53.3 centimeters in diameter). Yet this 3 percent of trees stored 42 percent of the aboveground carbon there, the team reported in 2020 in Frontiers in Forests and Global Change. An earlier study, with 48 sites worldwide and more than 5 million tree trunks, found that the largest 1 percent of trees store about 50 percent of the aboveground carbon-filled biomass.

    Plant paradise

    The island nation of Madagascar was an irresistible place for the Missouri Botanical Garden to start trying to conserve forests. Off the east coast of Africa, the island stretches more than the distance from Savannah, Ga., to Toronto, and holds more than 12,000 named species of trees, other flowering plants and ferns. Madagascar “is absolute nirvana,” says MBG botanist James S. Miller, who has spent decades exploring the island’s flora.

    The Ravenala traveler’s tree is widely grown, but native only to Madagascar.CEPHOTO, UWE ARANAS/WIKIMEDIA COMMONS (CC BY-SA 3.0)

    Just consider the rarities. Of the eight known species of baobab trees, which raise a fat trunk to a cartoonishly spindly tuft of little branches on top, six are native to Madagascar. Miller considers some 90 percent of the island’s plants as natives unique to the country. “It wrecks you” for botanizing elsewhere, Miller says.

    He was rooting for his MBG colleagues Randrianasolo and Birkinshaw in their foray to Madagascar’s Agnalazaha forest. Several months after getting roasted as liars by residents, the two got word that the skeptics had decided to give protection a chance after all.

    The Agnalazaha residents wanted to make sure, however, that the Missouri group realized the solemnity of their promise. Randrianasolo had to return to the island for a ceremony of calling the ancestors as witnesses to the new partnership and marking the occasion with the sacrifice of a cow. A pact with generations of deceased residents may be an unusual form of legal involvement, but it carried weight. Randrianasolo bought the cow.

    Randrianasolo looked for ways to be helpful. MBG worked on improving the village’s rice yields, and supplied starter batches of vegetable seeds for expanding home gardens. The MBG staff helped the forest residents apply for conservation funds from the Malagasy government. A new tree nursery gave villagers an alternative to cutting timber in the forest. The nursery also meant some jobs for local people, which further improved relationships.

    Trying to build trust with people living near southeastern Madagascar’s coast was the first task the Missouri Botanical Garden faced in efforts to conserve the Agnalazaha forest.Courtesy of the staff of the Missouri Botanical Garden, St. Louis and Madagascar

    The MBG staff now works with Malagasy communities to preserve forests at 11 sites dotted in various ecosystems in Madagascar. Says Randrianasolo: “You have to be patient.”

    Today, 19 years after his first visit among the mourners, Agnalazaha still stands.

    Saving forests is not a simple matter of just meeting basic needs of people living nearby, says political scientist Nadia Rabesahala Horning of Middlebury College in Vermont, who published The Politics of Deforestation in Africa in 2018. Her Ph.D. work, starting in the late 1990s, took her to four remote forests in her native Madagascar. The villagers around each forest followed different rules for harvesting timber, finding places to graze livestock and collecting medicinal plants.

    Three of the forests shrank, two of them rapidly, over the decade. One, called Analavelona, however, barely showed any change in the aerial views Horning used to look for fraying forests.

    Near Madagascar’s Analavelona sacred forest, taxonomist Armand Randrianasolo (blue cap) joins (from left) Miandry Fagnarena, Rehary, and Tefy Andriamihajarivo to collect a surprising new species in the mango family (green leaves at front of image). The Spondias tefyi, named for Tefy and his efforts to protect the island’s biodiversity, is the first wild relative of the popular hog plum found outside of South America or Asia.Courtesy of the staff of the Missouri Botanical Garden, St. Louis and Madagascar

    The people living around Analavelona revered it as a sacred place where their ancestors dwelled. Living villagers made offerings before entering, and cut only one kind of tree, which they used for coffins.

    Since then, Horning’s research in Tanzania and Uganda has convinced her that forest conservation can happen only under very specific conditions, she says. The local community must be able to trust that the government won’t let some commercial interest or a political heavyweight slip through loopholes to exploit a forest that its everyday neighbors can’t touch. And local people must be able to meet their own needs too, including the spiritual ones.

    A different kind of essential

    Tied with yarn to nearly 3,000 trees in a Maryland forest, tags displayed the names of the people lost on 9/11. The memorial, organized by ecologist Joan Maloof who runs the Old-Growth Forest Network, helped protect a patch of woods where people could go for solace and meditation.Friends of the Forest, Salisbury

    Another constellation of old forests, on the other side of the world, sports some less-than-obvious similarities. Ecologist Joan Maloof launched the Old-Growth Forest Network in 2011 to encourage people to save the remaining scraps of U.S. old-growth forests. Her bold idea: to permanently protect one patch of old forest in each of the more than 2,000 counties in the United States where forests can grow.

    She calls for strong legal measures, such as conservation easements that prevent logging, but also recognizes the need to convey the emotional power of communing with nature. One of the early green spots she and colleagues campaigned for was not old growth, but it had become one of the few left unlogged where she lived on Maryland’s Eastern Shore.

    She heard about Buddhist monks in Thailand who had ordained trees as monks because loggers revered the monks, so the trees were protected. A month after the 9/11 terrorist attacks, she was inspired to turn the Maryland forest into a place to remember the victims. By putting each victim’s name on a metal tag and tying it to a tree, she and other volunteers created a memorial with close to 3,000 trees. The local planning commission, she suspected, would feel awkward about approving timber cutting from that particular stand. She wasn’t party to their private deliberations, but the forest still stands.

    In 1973, high school freshman Doug Hefty wrote more than 80 pages about the value of Saddler’s Woods in Haddon Township, N.J. His typed report, with its handmade cover, played a dramatic role in saving the forest. Saddler’s Woods Conservation Association

    As of Earth Day 2021, the network had about 125 forests around the country that should stay forests in perpetuity. Their stories vary widely, but are full of local history and political maneuvering.

     In southern New Jersey, Joshua Saddler, an escaped enslaved man from Maryland, acquired part of a small forest in the mid-1880s and bequeathed it to his wife with the stipulation that it not be logged. His section was logged anyway, and the rest of the original old forest was about to meet the same fate. In 1973, high school student Doug Hefty wrote more than 80 pages on the forest’s value — and delivered it to the developer. In this case, life delivered a genuine Hollywood ending. The developer relented, and scaled back the project, stopping across the street from the woods.

    In 1999, however, developers once again eyed the forest, says Janet Goehner-Jacobs, who heads the Saddler’s Woods Conservation Association. It took four years, but now, she and the forests’ other fans have a conservation easement forbidding commercial development or logging, giving the next generation better tools to protect the forest.

    Goehner-Jacobs had just moved to the area and fallen in love with that 10-hectare patch of green in the midst of apartment buildings and strip malls. When she first happened upon the forest and found the old-growth section, “I just instinctively knew I was seeing something very different.”

    Saddler’s Woods, with a scrap of old-growth forest, has survived in the rush of development in suburban New Jersey thanks to generations of dedicated forest lovers.Saddler’s Woods Conservation Association More

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    Why planting tons of trees isn’t enough to solve climate change

    Trees are symbols of hope, life and transformation. They’re also increasingly touted as a straightforward, relatively inexpensive, ready-for-prime-time solution to climate change.

    When it comes to removing human-caused emissions of the greenhouse gas carbon dioxide from Earth’s atmosphere, trees are a big help. Through photosynthesis, trees pull the gas out of the air to help grow their leaves, branches and roots. Forest soils can also sequester vast reservoirs of carbon.

    Earth holds, by one estimate, as many as 3 trillion trees. Enthusiasm is growing among governments, businesses and individuals for ambitious projects to plant billions, even a trillion more. Such massive tree-planting projects, advocates say, could do two important things: help offset current emissions and also draw out CO2 emissions that have lingered in the atmosphere for decades or longer.

    Even in the politically divided United States, large-scale tree-planting projects have broad bipartisan support, according to a spring 2020 poll by the Pew Research Center. And over the last decade, a diverse garden of tree-centric proposals — from planting new seedlings to promoting natural regrowth of degraded forests to blending trees with crops and pasturelands — has sprouted across the international political landscape.

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    Trees “are having a bit of a moment right now,” says Joe Fargione, an ecologist with The Nature Conservancy who is based in Minneapolis. It helps that everybody likes trees. “There’s no anti-tree lobby. [Trees] have lots of benefits for people. Not only do they store carbon, they help provide clean air, prevent soil erosion, shade and shelter homes to reduce energy costs and give people a sense of well-being.”

    Conservationists are understandably eager to harness this enthusiasm to combat climate change. “We’re tapping into the zeitgeist,” says Justin Adams, executive director of the Tropical Forest Alliance at the World Economic Forum, an international nongovernmental organization based in Geneva. In January 2020, the World Economic Forum launched the One Trillion Trees Initiative, a global movement to grow, restore and conserve trees around the planet. One trillion is also the target for other organizations that coordinate global forestation projects, such as Plant-for-the-Planet’s Trillion Tree Campaign and Trillion Trees, a partnership of the World Wildlife Fund, the Wildlife Conservation Society and other conservation groups.

    Yet, as global eagerness for adding more trees grows, some scientists are urging caution. Before moving forward, they say, such massive tree projects must address a range of scientific, political, social and economic concerns. Poorly designed projects that don’t address these issues could do more harm than good, the researchers say, wasting money as well as political and public goodwill. The concerns are myriad: There’s too much focus on numbers of seedlings planted, and too little time spent on how to keep the trees alive in the long term, or in working with local communities. And there’s not enough emphasis on how different types of forests sequester very different amounts of carbon. There’s too much talk about trees, and not enough about other carbon-storing ecosystems.

    “There’s a real feeling that … forests and trees are just the idea we can use to get political support” for many, perhaps more complicated, types of landscape restoration initiatives, says Joseph Veldman, an ecologist at Texas A&M University in College Station. But that can lead to all kinds of problems, he adds. “For me, the devil is in the details.”

    The root of the problem

    The pace of climate change is accelerating into the realm of emergency, scientists say. Over the last 200 years, human-caused emissions of greenhouse gases, including CO2 and methane, have raised the average temperature of the planet by about 1 degree Celsius (SN: 12/22/18 & 1/5/19, p. 18).

    The litany of impacts of this heating is familiar by now. Earth’s poles are rapidly shedding ice, which raises sea levels; the oceans are heating up, threatening fish and food security. Tropical storms are becoming rainier and lingering longer, and out of control wildfires are blazing from the Arctic to Australia (SN: 12/19/20 & 1/2/21, p. 32).

    The world’s oceans and land-based ecosystems, such as forests, absorb about half of the carbon emissions from fossil fuel burning and other industrial activities. The rest goes into the atmosphere. So “the majority of the solution to climate change will need to come from reducing our emissions,” Fargione says. To meet climate targets set by the 2015 Paris Agreement, much deeper and more painful cuts in emissions than nations have pledged so far will be needed in the next 10 years.

    We invest a lot in tree plantings, but we are not sure what happens after that. Lalisa Duguma

    But increasingly, scientists warn that reducing emissions alone won’t be enough to bring Earth’s thermostat back down. “We really do need an all-hands-on-deck approach,” Fargione says. Specifically, researchers are investigating ways to actively remove that carbon, known as negative emissions technologies. Many of these approaches, such as removing CO2 directly from the air and converting it into fuel, are still being developed.

    But trees are a ready kind of negative emissions “technology,” and many researchers see them as the first line of defense. In its January 2020 report, “CarbonShot,” the World Resources Institute, a global nonprofit research organization, suggested that large and immediate investments in reforestation within the United States will be key for the country to have any hope of reaching carbon neutrality — in which ongoing carbon emissions are balanced by carbon withdrawals — by 2050. The report called for the U.S. government to invest $4 billion a year through 2030 to support tree restoration projects across the United States. Those efforts would be a bridge to a future of, hopefully, more technologies that can pull large amounts of carbon out of the atmosphere.

    The numbers game

    Earth’s forests absorb, on average, 16 billion metric tons of CO2 annually, researchers reported in the March Nature Climate Change. But human activity can turn forests into sources of carbon: Thanks to land clearing, wildfires and the burning of wood products, forests also emit an estimated 8.1 billion tons of the gas back to the atmosphere.

    That leaves a net amount of 7.6 billion tons of CO2 absorbed by forests per year — roughly a fifth of the 36 billion tons of CO2 emitted by humans in 2019. Deforestation and forest degradation are rapidly shifting the balance. Forests in Southeast Asia now emit more carbon than they absorb due to clearing for plantations and uncontrolled fires. The Amazon’s forests may flip from carbon sponge to carbon source by 2050, researchers say (SN Online: 1/10/20). The priority for slowing climate change, many agree, should be saving the trees we have.

    Just how many more trees might be mustered for the fight is unclear, however. In 2019, Thomas Crowther, an ecologist at ETH Zurich, and his team estimated in Science that around the globe, there are 900 million hectares of land — an area about the size of the United States — available for planting new forests and reviving old ones (SN: 8/17/19, p. 5). That land could hold over a trillion more trees, the team claimed, which could trap about 206 billion tons of carbon over a century.

    That study, led by Jean-Francois Bastin, then a postdoc in Crowther’s lab, was sweeping, ambitious and hopeful. Its findings spread like wildfire through media, conservationist and political circles. “We were in New York during Climate Week [2019], and everybody’s talking about this paper,” Adams recalls. “It had just popped into people’s consciousness, this unbelievable technology solution called the tree.”

    To channel that enthusiasm, the One Trillion Trees Initiative incorporated the study’s findings into its mission statement, and countless other tree-planting efforts have cited the report.

    But critics say the study is deeply flawed, and that its accounting — of potential trees, of potential carbon uptake — is not only sloppy, but dangerous. In 2019, Science published five separate responses outlining numerous concerns. For example, the study’s criteria for “available” land for tree planting were too broad, and the carbon accounting was inaccurate because it assumes that new tree canopy cover equals new carbon storage. Savannas and natural grasslands may have relatively few trees, critics noted, but these regions already hold plenty of carbon in their soils. When that carbon is accounted for, the carbon uptake benefit from planting trees drops to perhaps a fifth of the original estimate.

    Trees are having a bit of a moment right now. Joe Fargione

    There’s also the question of how forests themselves can affect the climate. Adding trees to snow-covered regions, for example, could increase the absorption of solar radiation, possibly leading to warming.

    “Their numbers are just so far from anything reasonable,” Veldman says. And focusing on the number of trees planted also sets up another problem, he adds — an incentive structure that is prone to corruption. “Once you set up the incentive system, behaviors change to basically play that game.”

    Adams acknowledges these concerns. But, the One Trillion Trees Initiative isn’t really focused on “the specifics of the math,” he says, whether it’s the number of trees or the exact amount of carbon sequestered. The goal is to create a powerful climate movement to “motivate a community behind a big goal and a big vision,” he says. “It could give us a fighting chance to get restoration right.”

    Other nonprofit conservation groups, like the World Resources Institute and The Nature Conservancy, are trying to walk a similar line in their advocacy. But some scientists are skeptical that governments and policy makers tasked with implementing massive forest restoration programs will take note of such nuances.

    “I study how government bureaucracy works,” says Forrest Fleischman, who researches forest and environmental policy at the University of Minnesota in St. Paul. Policy makers, he says, are “going to see ‘forest restoration,’ and that means planting rows of trees. That’s what they know how to do.”

    Counting carbon

    How much carbon a forest can draw from the atmosphere depends on how you define “forest.” There’s reforestation — restoring trees to regions where they used to be — and afforestation — planting new trees where they haven’t historically been. Reforestation can mean new planting, including crop trees; allowing forests to regrow naturally on lands previously cleared for agriculture or other purposes; or blending tree cover with croplands or grazing areas.

    In the past, the carbon uptake potential of letting forests regrow naturally was underestimated by 32 percent, on average — and by as much as 53 percent in tropical forests, according to a 2020 study in Nature. Now, scientists are calling for more attention to this forestation strategy.

    If it’s just a matter of what’s best for the climate, natural forest regrowth offers the biggest bang for the buck, says Simon Lewis, a forest ecologist at University College London. Single-tree commercial crop plantations, on the other hand, may meet the technical definition of a “forest” — a certain concentration of trees in a given area — but factor in land clearing to plant the crop and frequent harvesting of the trees, and such plantations can actually release more carbon than they sequester.

    Comparing the carbon accounting between different restoration projects becomes particularly important in the framework of international climate targets and challenges. For example, the 2011 Bonn Challenge is a global project aimed at restoring 350 million hectares by 2030. As of 2020, 61 nations had pledged to restore a total of 210 million hectares of their lands. The potential carbon impact of the stated pledges, however, varies widely depending on the specific restoration plans.

    In a 2019 study in Nature, Lewis and his colleagues estimated that if all 350 million hectares were allowed to regrow natural forest, those lands would sequester about 42 billion metric tons (gigatons in chart above) of carbon by 2100. Conversely, if the land were to be filled with single-tree commercial crop plantations, carbon storage drops to about 1 billion metric tons. And right now, plantations make up a majority of the restoration plans submitted under the Bonn Challenge.

    Striking the right balance between offering incentives to landowners to participate while also placing certain restrictions remains a tricky and long-standing challenge, not just for combating the climate emergency but also for trying to preserve biodiversity (SN: 8/1/20, p. 18). Since 1974, Chile, for example, has been encouraging private landowners to plant trees through subsidies. But landowners are allowed to use these subsidies to replace native forestlands with profitable plantations. As a result, Chile’s new plantings not only didn’t increase carbon storage, they also accelerated biodiversity losses, researchers reported in the September 2020 Nature Sustainability.

    The reality is that plantations are a necessary part of initiatives like the Bonn Challenge, because they make landscape restoration economically viable for many nations, Lewis says. “Plantations can play a part, and so can agroforestry as well as areas of more natural forest,” he says. “It’s important to remember that landscapes provide a whole host of services and products to people who live there.”

    But he and others advocate for increasing the proportion of forestation that is naturally regenerated. “I’d like to see more attention on that,” says Robin Chazdon, a forest ecologist affiliated with the University of the Sunshine Coast in Australia as well as with the World Resources Institute. Naturally regenerated forests could be allowed to grow in buffer regions between farms, creating connecting green corridors that could also help preserve biodiversity, she says. And “it’s certainly a lot less expensive to let nature do the work,” Chazdon says.

    Indeed, massive tree-planting projects may also be stymied by pipeline and workforce issues. Take seeds: In the United States, nurseries produce about 1.3 billion seedlings per year, Fargione and colleagues calculated in a study reported February 4 in Frontiers in Forests and Global Change. To support a massive tree-planting initiative, U.S. nurseries would need to at least double that number.

    A tree-planting report card

    From China to Turkey, countries around the world have launched enthusiastic national tree-planting efforts. And many of them have become cautionary tales.

    China kicked off a campaign in 1978 to push back the encroaching Gobi Desert, which has become the fastest-growing desert on Earth due to a combination of mass deforestation and overgrazing, exacerbated by high winds that drive erosion. China’s Three-North Shelter Forest Program, nicknamed the Great Green Wall, aims to plant a band of trees stretching 4,500 kilometers across the northern part of the country. The campaign has involved millions of seeds dropped from airplanes and millions more seedlings planted by hand. But a 2011 analysis suggested that up to 85 percent of the plantings had failed because the nonnative species chosen couldn’t survive in the arid environments they were plopped into.

    A woman places straw in March 2019 to fix sand in place before planting trees at the edge of the Gobi Desert in China’s Minqin County. Her work is part of a private tree-planting initiative that dovetails with the government’s decades-long effort to build a “green wall” to hold back the desert.WANG HE/GETTY IMAGES PLUS

    More recently, Turkey launched its own reforestation effort. On November 11, 2019, National Forestation Day, volunteers across the country planted 11 million trees at more than 2,000 sites. In Turkey’s Çorum province, 303,150 saplings were planted in a single hour, setting a new world record.

    Within three months, however, up to 90 percent of the new saplings inspected by Turkey’s agriculture and forestry trade union were dead, according to the union’s president, Şükrü Durmuş, speaking to the Guardian (Turkey’s minister of agriculture and forestry denied that this was true). The saplings, Durmuş said, died due to a combination of insufficient water and because they were planted at the wrong time of year, and not by experts.

    Some smaller-scale efforts also appear to be failing, though less spectacularly. Tree planting has been ongoing for decades in the Kangra district of Himachal Pradesh in northern India, says Eric Coleman, a political scientist at Florida State University in Tallahassee, who’s been studying the outcomes. The aim is to increase the density of the local forests and provide additional forest benefits for communities nearby, such as wood for fuel and fodder for grazing animals. How much money was spent isn’t known, Coleman says, because there aren’t records of how much was paid for seeds. “But I imagine it was in the millions and millions of dollars.”

    Coleman and his colleagues analyzed satellite images and interviewed members of the local communities. They found that the tree planting had very little impact one way or the other. Forest density didn’t change much, and the surveys suggested that few households were gaining benefits from the planted forests, such as gathering wood for fuel, grazing animals or collecting fodder.

    But massive tree-planting efforts don’t have to fail. “It’s easy to point to examples of large-scale reforestation efforts that weren’t using the right tree stock, or adequately trained workforces, or didn’t have enough investment in … postplanting treatments and care,” Fargione says. “We … need to learn from those efforts.”

    Speak for the trees

    Forester Lalisa Duguma of World Agroforestry in Nairobi, Kenya, and colleagues explored some of the reasons for the very high failure rates of these projects in a working paper in 2020. “Every year there are billions of dollars invested [in tree planting], but forest cover is not increasing,” Duguma says. “Where are those resources going?”

    In 2019, Duguma raised this question at the World Congress on Agroforestry in Montpellier, France. He asked the audience of scientists and conservationists: “How many of you have ever planted a tree seedling?” To those who raised their hands, he asked, “Have they grown?”

    Some respondents acknowledged that they weren’t sure. “Very good! That’s what I wanted,” he told them. “We invest a lot in tree plantings, but we are not sure what happens after that.”

    It comes down to a deceptively simple but “really fundamental” point, Duguma says. “The narrative has to change — from tree planting to tree growing.”

    The good news is that this point has begun to percolate through the conservationist world, he says. To have any hope of success, restoration projects need to consider the best times of year to plant seeds, which seeds to plant and where, who will care for the seedlings as they grow into trees, how that growth will be monitored, and how to balance the economic and environmental needs of people in developing countries where the trees might be planted.

    “That is where we need to capture the voice of the people,” Duguma says. “From the beginning.”

    Even as the enthusiasm for tree planting takes root in the policy world, there’s a growing awareness among researchers and conservationists that local community engagement must be built into these plans; it’s indispensable to their success.

    “It will be almost impossible to meet these targets we all care so much about unless small farmers and communities benefit more from trees,” as David Kaimowitz of the United Nations’ Food and Agriculture Organization wrote March 19 in a blog post for the London-based nonprofit International Institute for Environment and Development.

    For one thing, farmers and villagers managing the land need incentives to care for the plantings and that includes having clear rights to the trees’ benefits, such as food or thatching or grazing. “People who have insecure land tenure don’t plant trees,” Fleischman says.

    Fleischman and others outlined many of the potential social and economic pitfalls of large-scale tree-planting projects last November in BioScience. Those lessons boil down to this, Fleischman says: “You need to know something about the place … the political dynamics, the social dynamics.… It’s going to be very different in different parts of the world.”

    The old cliché — think globally, act locally — may offer the best path forward for conservationists and researchers trying to balance so many different needs and still address climate change.

    “There are a host of sociologically and biologically informed approaches to conservation and restoration that … have virtually nothing to do with tree planting,” Veldman says. “An effective global restoration agenda needs to encompass the diversity of Earth’s ecosystems and the people who use them.”

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    Human-driven climate change sent Pacific Northwest temperatures soaring

    The deadly heat wave that baked the Pacific Northwest in late June would have been “virtually impossible” without human-caused climate change, an international team of scientists announced July 7.

    In fact, the temperatures were so extreme — Portland, Ore., reached a staggering 47° Celsius (116° Fahrenheit) on June 29, while Seattle surged to 42° C (108° F) — that initial analyses suggested they were impossible even with climate change, Geert Jan van Oldenborgh, a climate scientist with the Royal Netherlands Meteorological Institute in De Bilt, said at a news conference to announce the team’s findings. “This was an extraordinary event. I don’t know what English word covers it.”

    Climate change due to greenhouse gas emissions made the region’s heat wave at least 150 times more likely to occur, the team found. As emissions and global temperatures continue to rise, such extreme heat events could happen in the region as often as every five to 10 years by the end of the century.  

    It’s not just that numerous temperature records were broken, van Oldenborgh said. It’s that the observed temperatures were so far outside of historical records, breaking those records by as much as 5 degrees C in many places — and a full month before usual peak temperatures for the region. The observations were also several degrees higher than the upper temperature limits predicted by most climate simulations for the heat waves, even taking global warming into account.

    Coming just about a week after the heat wave broke, the new study is the latest real-time climate attribution effort by scientists affiliated with the World Weather Attribution network. Van Oldenborgh and University of Oxford climate scientist Friederike Otto founded the group in 2014 to conduct quick analyses of extreme events such as the 2020 Siberian heat wave (SN: 7/15/20).

    In the current study, 27 researchers focused on how the observed temperatures from June 27 to June 29 compared with annual maximum temperatures over the last 50 years for locations across the northwestern United States and southwestern Canada. The team then used 21 different climate simulations of temperatures to analyze the intensity of such a heat wave in the region with and without the influence of greenhouse gas warming.

    Earth has already warmed by about 1.2 degrees C relative to preindustrial times. That warming, the researchers determined, increased the intensity of the heat wave by about 2 degrees C. Once global warming increases to 2 degrees C, future heat waves may become even more intense (SN: 12/17/18). Those heat waves could be another 1.3 degrees C hotter, the researchers found.

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    That poses a real danger. The late June heat wave took a painful toll (SN: 6/29/21), killing several hundred people — “almost certainly” an underestimate, the researchers say. On June 29, Lytton, a small village in British Columbia, set an all-time Canadian temperature record of 49.6° C (121.3° F). The heat may have exacerbated wildfires that, a day later, swept through British Columbia’s Fraser Canyon region, burning 90 percent of the village, according to local officials. Meanwhile, the U.S. West and southwestern Canada are already bracing for another round of soaring temperatures.

    One possible reason for the startling intensity of this heat wave is that, while climate change amped up the temperatures, what happened was still a very rare, unlucky event for the region. How rare isn’t easy to say, given that the observed temperatures were so far off the charts, the researchers say. Under current climate conditions, simulations suggest that such a heat wave might occur once every 1,000 years — but these events will become much more common in future as the climate changes.

    By the end of June 2021, more than 40 wildfires burned across Canada’s British Columbia, exacerbated by extreme dryness and the intense heat. One fire burned 90 percent of the town of Lytton, which had set a new temperature record for the country the day before. The fire also generated a massive storm-producing plume of smoke called a pyrocumulonimbus cloud.NASA

    Another possibility is grimmer: Climate simulations may not accurately capture what really happens during extreme heat waves. “Climate science has been a bit complacent” about simulating heat waves, assuming that heat wave temperatures would increase linearly along with rising global temperatures, Otto said. But now, Earth’s climate system may have entered a new state in which other climatic factors, such as drier soils or changes to jet stream circulation, are exacerbating the heat in more difficult-to-predict, less linear ways.

    The new study didn’t seek to determine which of these possibilities is true, though the team plans to tackle this question over the next few months. However, many scientists have already noted the inability of current climate models to capture what’s really going on.  

    “I agree that it is virtually impossible that the [Pacific Northwest] heat wave would have occurred with the observed intensity in the absence of climate change,” Michael Mann, a climate scientist at Penn State who wasn’t involved in the attribution study, commented via e-mail. “But the models used don’t capture the jet stream phenomenon … that WE KNOW played an important role in this event.”

    Disproportionate warming of the Arctic region alters temperature gradients high in the atmosphere, which can lead to a wavier jet stream, Mann wrote in the New York Times June 29. That waviness can exacerbate and prolong extreme weather events, such as the heat dome centered over the Pacific Northwest in late June.

    This recent heat wave wasn’t just a major disaster, but also posed major scientific questions, van Oldenborgh said. Such an event “would have been judged impossible last year. All of us have just dialed down our certainty of how heat waves behave,” he added. “[We] are much less certain of how the climate affects heat waves than we were two weeks ago.” More

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    A tweaked yeast can make ethanol from cornstalks and a harvest’s other leftovers

    When corn farmers harvest their crop, they often leave the stalks, leaves and spent cobs to rot in the fields. Now, engineers have fashioned a new strain of yeast that can convert this inedible debris into ethanol, a biofuel. If the process can be scaled up, this largely untapped renewable energy source could help reduce reliance on fossil fuels.

    Previous efforts to convert this fibrous material, called corn stover, into fuel met with limited success. Before yeasts can do their job, corn stover must be broken down, but this process often generates by-products that kill yeasts. But by tweaking a gene in common baker’s yeast, researchers have engineered a strain that can defuse those deadly by-products and get on with the job of turning sugar into ethanol.

    The new yeast was able to produce over 100 grams of ethanol for every liter of treated corn stover, an efficiency comparable to the standard process using corn kernels to make the biofuel, the researchers report June 25 in Science Advances.

    “They’ve produced a more resilient yeast,” says Venkatesh Balan, a chemical engineer at the University of Houston not involved in the research. The new strain may benefit biofuel producers trying to harness materials like corn stover, he says.

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    In the United States, most ethanol is made from corn, the country’s largest crop, and is mixed into most of the gasoline sold at gas stations. Corn ethanol is a renewable energy source, but it has limitations. Diverting corn to make ethanol can detract from the food supply, and expanding cropland just to plant corn for biofuel clears natural habitats (SN: 12/21/20). Converting inedible corn stover into ethanol could increase the biofuel supply without having to plant more crops.

    “Corn can’t really displace petroleum as a raw material for fuels,” says metabolic engineer Felix Lam of MIT. “But we have an alternative.”

    Lam and colleagues started with Saccharomyces cerevisiae, or common baker’s yeast. Like sourdough bakers and brewers, biofuel producers already use yeast: It can convert sugars in corn kernels into ethanol (SN: 9/19/17).

    But unlike corn kernels with easy-access sugars, corn stover contains sugars bound in lignocellulose, a plant compound that yeast can’t break down. Applying harsh acids can free these sugars, but the process generates toxic by-products called aldehydes that can kill yeasts.

    But Lam’s team had an idea — convert the aldehydes into something tolerable to yeast. The researchers already knew that by adjusting the chemistry of the yeast’s growing environment, they could improve its tolerance to alcohol, which is also harmful at high concentrations. With that in mind, Lam and colleagues homed in on a yeast gene called GRE2, which helps convert aldehydes into alcohol. The team randomly generated about 20,000 yeast variants, each with a different, genetically modified version of GRE2. Then, the researchers placed the horde of variants inside a flask that also contained toxic aldehydes to see which yeasts would survive.

    Multiple variants survived the gauntlet, but one dominated. With this battle-tested version of GRE2, the researchers found that the modified baker’s yeast could produce ethanol from treated corn stover almost as efficiently as from corn kernels. What’s more, the yeast could generate ethanol from other woody materials, including wheat straw and switchgrass (SN: 1/14/14). “We have a single strain that can accomplish all this,” Lam says.

    This strain resolves a key challenge in fermenting ethanol from fibrous materials like corn stover, Balan says. But “there are many more improvements that will have to happen to make this technology commercially viable,” he adds, such as logistical challenges in harvesting, transporting and storing large volumes of corn stover.

    “There are so many moving parts to this problem,” Lam acknowledges. But he thinks his team’s findings could help kick-start a “renewable pipeline” that harnesses underused, sustainable fuel sources. The vision, he says, is to challenge the reign of fossil fuels. More