OXON HILL, Md. — Even as technological advances allow astronomers to peer more deeply into the cosmos than ever before, new technologies also have the potential to create blinding pollution.
Three sources of pollution — space debris, radio interference and light pollution — already are particularly worrisome. And the situation is getting worse. In the next two decades, as many as 20,000 satellites could be launched into low Earth orbit, LEDs will become the dominant source of artificial light, and fifth-generation mobile networks will fill radio frequencies, speakers warned during the annual meeting of the American Astronomical Society. These sources of pollution could prevent astronomers from getting a clear look at the night sky, limiting the sensitivity and accuracy of their measurements. Space debris is perhaps the most nascent form of human pollution. But only six decades after Sputnik’s launch into pristine skies, the orbit around Earth is now filled with nearly 18,000 objects tracked by the United States Strategic Command. These objects range in size from about centimeter-long chunks of material to bus-sized satellites. Space debris can both damage existing space telescopes and reflect light, potentially confusing terrestrial telescopes. From Earth, a glint of light could be a distant star or just a hunk of metal.
“The worst is yet to come,” said Patrick Seitzer, an astronomer at the University of Michigan in Ann Arbor. “We’re going to double our catalog [of debris] over the next 20 years.” Aerospace company Boeing, for instance, has proposed launching a global network of nearly 3,000 satellites. Collisions between any two satellites can create thousands of pieces of debris.
Down on Earth, light pollution is a well-known phenomenon (SN: 7/9/16, p. 32) and the shift to LEDs, or light-emitting diodes, is worsening the problem. In 2010, LEDs constituted less than 1 percent of the American lighting market. Today, they account for about half of the market, and that share is expected to grow.
LEDs have environmental and economic benefits, being long-lived and energy efficient. But they emit a broad spectrum of light, including blue-rich light, which is particularly bad for astronomy. Blue-rich light scatters more easily than light with longer wavelengths, like yellow, which worsens sky glow and makes it tougher to see stars. Invisible to the naked eye, radio frequency interference is no less detrimental to astronomy than optical light pollution. For astronomers who observe the universe through radio waves generated by stars and galaxies, interference from an Earth-based source can easily drown out any far-off signal.
Just as radio channels close to each other in frequency can bleed into one another, creating static, so too can radio interference from different technologies bleed into the channels astronomers use to observe. As more and more space on the spectrum is gobbled up by new technology such as 5G mobile networks, radio astronomers will have to grapple with more potential interference. For instance, radar on driverless cars could affect radio astronomy operations up to 100 kilometers away, said Harvey Liszt, a radio astronomer at the National Radio Astronomy Observatory in Charlottesville, Va.
Faced with the prospect of encroaching technology on Earth, the late astronomer Jean Heidmann proposed in 1998 designating an area on the far side of the moon for an observatory that would be safe from space debris, light and radio pollution.
Short of that extreme solution, continuing government regulation of radio frequencies is crucial. “Without spectrum protection, radio astronomers would lose the ability to observe,” Liszt said. Astronomers may need to expand and secure radio quiet zones like the one surrounding the Green Bank Observatory in West Virginia to preserve a future for Earth-based radio astronomy.
When it comes to artificial light, none would be best. That’s a futile fight, astronomers agreed, but there are solutions. Flagstaff, Ariz., is adopting LED lights, but they are what’s called narrow-band amber LEDs, which limit sky glow because they resemble the yellow, low-pressure sodium lights astronomers prefer.
“Dark skies have become part of the culture here,” said astronomer Jeff Hall, director of the Lowell Observatory in Flagstaff. “It’s … a community value. We even have a company called Dark Sky Brewing.”
For now, many astronomers hope that such down-to-earth solutions to pollution will work.
Nerve cells in the brain make elaborate connections and exchange lightning-quick messages that captivate scientists. But these cells also sport simpler, hairlike protrusions called cilia. Long overlooked, the little stubs may actually have big jobs in the brain.
Researchers are turning up roles for nerve cell cilia in a variety of brain functions. In a region of the brain linked to appetite, for example, cilia appear to play a role in preventing obesity, researchers report January 8 in three studies in Nature Genetics. Cilia perched on nerve cells may also contribute to brain development, nerve cell communication and possibly even learning and memory, other research suggests.
“Perhaps every neuron in the brain possesses cilia, and most neuroscientists don’t know they’re there,” says Kirk Mykytyn, a cell biologist at Ohio State University College of Medicine in Columbus. “There’s a big disconnect there.” Most cells in the body — including those in the brain — possess what’s called a primary cilium, made up of lipid molecules and proteins. The functions these appendages perform in parts of the body are starting to come into focus (SN: 11/3/12, p. 16). Cilia in the nose, for example, detect smell molecules, and cilia on rod and cone cells in the eye help with vision. But cilia in the brain are more mysterious.
The new research offers some clarity. In one study, molecular geneticist Christian Vaisse of the University of California, San Francisco, and colleagues studied mutations in a protein called MC4R that are known to cause severe obesity in people. Experiments on mice showed that MC4R normally resides within the cilia on appetite-controlling nerve cells. But several of these mutations prevented MC4R from reaching those cells’ cilia from elsewhere in the cells, experiments on cells in dishes showed. And one of these mutations prevented MC4R from reaching nerve cell cilia in the brains of mice.
When the researchers interfered with ADCY3, a protein in the cilia that helps MC4R regulate appetite, the resulting mice became obese. Those results suggest that MC4R must reach the cilia in order to interact with ADCY3 and work properly. In the other two papers, scientists link the ADCY3 gene to obesity in people, providing more evidence that cilia are involved in obesity.
Story continues after graphic That link has already been found in rare cases. Mutations that affect cilia can cause severe obesity, as seen with diseases such as Bardet-Biedl syndrome. But the new results hint that abnormal cilia may be more widely involved in obesity. Earlier genetic studies have tied obesity to the MC4R gene, which the mouse study now shows to be important in cilia. It’s possible that many of the common genetic obesity culprits may actually be tinkering with the primary cilia, Vaisse says. It’s not yet clear why the MC4R protein needs to reach the cilia to control appetite, Mykytyn says. It’s possible that the appendages possess the right mix of helper proteins that aid MC4R in its job. Or cilia might change the way the protein works, allowing it to be more efficient.
Although many questions remain, the new study “opens up the window a little more” on what cilia actually do in the brain, how they function — and what can happen when they don’t, says Nick Berbari, a cell biologist at Indiana University-Purdue University Indianapolis.
It’s possible that cilia have even broader roles in memory, learning and perhaps mental health, Berbari says. Mice without normal cilia in parts of their brain had trouble remembering a painful shock and recognizing familiar objects, he and colleagues reported in PLOS One in 2014. Though speculative, impaired cilia signaling may even be involved in disorders such as depression and schizophrenia, the researchers wrote in that study.
Other brain functions are getting assigned to cilia, too. Mykytyn and his colleagues have found a protein in cilia that detects the chemical messenger dopamine, a signal that helps certain nerve cells operate. And like the obesity-related MC4R protein, this dopamine detector needs to be on a cilium to work properly.
Cilia may be capable of much more than acting as little antennae that sense signals outside of nerve cells. The stubby appendages may actually be able to send messages themselves, results from a 2014 study in Current Biology suggest. There, scientists reported that nerve cell cilia in C. elegans worms could float little packets containing chemical messages into the space between cells. Those signals may have a role in the worms’ behavior, the researchers suspect.
Examining the various roles of cilia in the brain is tough, Mykytyn says. There is no simple way to separate cilia from the rest of cells’ outer membranes. The challenges are greater with elaborate nerve cells, where cilia can be relatively small.
But advances in microscopy and genetic tricks that can allow scientists to manipulate specific aspects of cilia may reveal more about how these “underappreciated appendages” work, Berbari says — even in places as mysterious as the brain.
Toad versus bombardier beetle is almost a fair fight. Toads are hugely bigger, can tongue-strike in an eyeblink and swallow all kinds of nasty stuff. But bombardier beetles can shoot hot steam and noxious chemicals from their back ends.
In a lab face-off, 43 percent of Pheropsophus jessoensis bombardiers escaped alive after being swallowed by toads, a pair of researchers at Kobe University in Japan report February 7 in Biology Letters. These lucky beetles were vomited up — in one case, 107 minutes after being gulped — covered with goo, but still able to pull themselves together and walk away. Fifteen of the 16 beetles coughed up into daylight lived for at least 17 days, with one still going 562 days later. Scalding internal beetle blasts proved vital in persuading the toads to spit the bugs up, ecologists Shinji Sugiura and Takuya Sato report. The pair prodded beetles into spraying until no more defensive chemicals remained, and then fed defenseless beetles to toads. The toads kept almost all of these beetles down.
The bombardier group of more than 600 beetle species has become a textbook example of chemical defense (SN Online: 4/30/15). When provoked, the beetles mix two substances inside their abdomens that react explosively, then shoot this cocktail out of their bodies in a noxious stream that can reach around 100° Celsius. Yet the defenses of very few of the species have been tested, Sugiura says.
P. jessoensis beetles are common in East Asia. In the lab, wild-caught toads (Bufo japonicus and B. torrenticola) willingly swallowed these beetles. With each big gulp, the researchers listened for the sound of an outraged beetle blast inside the toad. “Not easy to hear,” Sugiura says, but it’s possible to catch a slight bu or vu sound. Surviving beetles spent 12 to 107 minutes in a toad stomach with average stomach time in the 40-minute range. To vomit, a toad has to sort of turn its stomach inside out, which isn’t a quick process. So far, researchers don’t know if the swallowed beetles have any tricks for survival, such as somehow chemically lessening the power of toad gastric juices.
Making a toad give back its lunch is an accomplishment. “Toads are tough,” says evolutionary ecologist Rick Shine of the University of Sydney, who has studied cane toads. They can eat bees, though he has run across an account suggesting even this voracious species finds swallowing a big carpenter bee a bit uncomfortable, performing “abdominal motions suggestive of the Hawaiian hula.”
Swallowing a bombardier beetle sounds much worse, says Gregory Brown, also with the University of Sydney. That hot chemical blast would be like “having a small bomb go off in their stomachs,” he says. “What does surprise me is that the defense only worked around 50 percent of the time.”
There’s a planet just next door that could explain the origins of life in the universe. It was probably once covered in oceans (SN Online: 8/1/17). It may have been habitable for billions of years (SN Online: 8/26/16). Astronomers are desperate to land spacecraft there.
No, not Mars. That tantalizing planet is Venus. But despite all its appeal, Venus is one of the hardest places in the solar system to get to know. That’s partly because modern Venus is famously hellish, with temperatures hot enough to melt lead and choking clouds of sulfuric acid. “If you wanted sinners to fry in their own juice, Venus would be the place to send them,” V. S. Avduevsky, deputy director of the Soviet Union’s spaceflight control center, said in 1976 after his country’s Venera 9 and 10 landers returned their dismal view of the planet’s landscape (SN: 6/19/76, p. 388).
Today, would-be Venus explorers say they have the technology to master those damning conditions. “There’s a perception that Venus is a very difficult place to have a mission,” says planetary scientist Darby Dyar of Mount Holyoke College in South Hadley, Mass. “Everybody knows about the high pressures and temperatures on Venus, so people think we don’t have technology to survive that. The answer is that we do.”
And researchers are actively developing more Venus-defying technology while vying for the financial support needed to get a mission off the ground.
In 2017, five Venus projects — including a mapping orbiter, a probe that would taste the atmosphere as it fell through it, and landers that would zap rocks with lasers — failed to get NASA’s green light for flight. But all were considered technologically ready to go, and the laser team got funding for technology development. “NASA’s mission selection process is highly competitive,” says Thomas Zurbuchen, associate administrator for NASA’s science mission programs in Washington, D.C. “Earth’s so-called ‘twin’ planet Venus is a fascinating body, and of tremendous interest to our science community… the Venus community should continue to compete for future missions.” Visiting Venus From afar, Venus and Earth would look like equally promising targets in the search for alien life. Both are roughly the same size and mass, and Venus lies close to the sun’s habitable zone, where temperatures enable stable liquid water on a planet’s surface.
“We need to understand what made a planet go down the Venus path rather than the Earth path,” says astrobiologist David Grinspoon of the Planetary Science Institute, who is based in Washington, D.C.
A few orbiters have visited Venus in the past decade, including the European Space Agency’s Venus Express from 2006 to 2014, and the Japanese space agency’s Akatsuki, in orbit since December 2015. But despite dozens of proposed missions spanning almost 30 years, no NASA spacecraft has visited Earth’s twin since the Magellan craft ended its mission by plunging into Venus’ atmosphere in 1994 and burning up. And no spacecraft at all have landed on the Venusian surface since 1985.
One obvious barrier is Venus’ thick atmosphere which, in recent images from Akatsuki, makes the planet look like a smooth, milky marble. The atmosphere is 96.5 percent carbon dioxide, which blocks scientists’ view of the surface in almost all wavelengths of light. As recently as 2011, astronomers thought it was impossible to use spectroscopy — a technique that splits light from an object into different wavelengths to tell an object’s composition — from orbit to reveal what Venus’ surface is made of.
But it turns out that Venus’ atmosphere is transparent to at least five wavelengths of light that can help identify different minerals. Venus Express proved it would work: Looking at one infrared wavelength allowed astronomers to see hot spots that might be signs of active volcanism (SN Online: 6/19/15). An orbiter that used the other four wavelengths, too, could do even more, Dyar says.
Ground truth To really understand the surface, scientists want to go there. But a lander would have to contend with the opaque atmosphere while looking for a safe place to touch down. The best map of Venus’ surface, based on radar data from Magellan, is too low-resolution to show rocks or slopes that could topple a lander, says James Garvin of NASA’s Goddard Space Flight Center in Greenbelt, Md.
Garvin and his colleagues are testing a computer vision technique called Structure from Motion that could help a lander map its own landing site on the way down. Quickly analyzing many images of stationary objects taken from different angles as the spacecraft descends can create a 3-D rendering of the ground.
A tryout in a helicopter over a quarry in Maryland showed that the technology could plot boulders less than half a meter across, about the size of a basketball hoop. “With a handful of GoPro pictures, we made beautiful little topographic maps,” Garvin says. “We can do it at Venus even with this crappy atmosphere that is so murky you wouldn’t think it works.” He plans to present the experiment in March in The Woodlands, Texas, at the Lunar and Planetary Science Conference.
Once a lander has made it to Venus’ surface, it faces its next challenge: surviving.
The first landers on Venus, the Soviet Venera spacecraft in the 1970s and ‘80s, lasted around an hour each. The longevity record set by Venera 13 in 1982 was two hours and seven minutes. The planet’s surface is about 460° Celsius and its pressure is about 90 times that of Earth’s sea level, so spacecraft don’t have long before some crucial component is melted, crushed or corroded by the acidic atmosphere.
Modern missions are not expected to do much better: one hour minimum, five hours optimistically and 24 hours “in your wildest dreams,” Dyar says.
But a team at NASA’s Glenn Research Center in Cleveland is designing a lander that could last months. “We’re going to try to live on the surface of Venus,” says engineer Tibor Kremic of NASA Glenn. Instead of using bulk to absorb heat or countering it with refrigeration, the proposed lander, called LLISSE (Long-Lived In-Situ Solar System Explorer), would use simple electronics made of silicon carbide that can withstand Venusian temperatures. “They’re not Pentiums, but they’re able to provide a reasonable amount of functionality,” says NASA Glenn electronics engineer Gary Hunter.
The group has tested the circuits in a Venus simulation chamber called GEER (Glenn Extreme Environment Rig). “Think of a giant soup can,” but with 6-centimeter-thick walls, Kremic says. The circuits still worked after 21.7 days in a simulated Venus atmosphere, reported Philip Neudeck of NASA Glenn in AIP Advances in 2016. Scheduling issues put an end to the experiment, but the circuits could have lasted longer, Hunter says.
Ultimately, the team wants to build a prototype lander that can last for 60 days. On Venus, that would be long enough to act as a weather station, monitoring changes in the atmosphere over time. “That has never been done before,” Kremic says.
Reading rocks And that presents the next challenge: Planetary scientists have to figure out what the data are telling them.
Rocks interact with the Venusian atmosphere differently than with Earth’s or Mars’ atmospheres. Mineralogists identify rocks based on the light they reflect and emit, but high temperature and pressure can shift light in ways that depend on the mineral’s crystal structure. Even when scientists get data on Venusian rocks, interpretation could be tricky.
“We don’t even know what to look for,” Dyar says.
Ongoing experiments at GEER are helping set the baseline. Scientists can leave rocks and other materials in the chamber for months at a time just to see what happens to them. Dyar and her colleagues are doing similar experiments in a high-temperature chamber at the Institute of Planetary Research in Berlin.
“We try to understand the physics of how things happen on the Venus surface so we can be better prepared when we explore,” Kremic says. Two of the mission concepts NASA didn’t green-light use different strategies. VISAGE (Venus In-Situ Atmospheric and Geochemical Explorer) proposed bringing powdered rocks into a chamber inside the lander that maintains Earthlike conditions and measuring them there.
VICI (Venus In-situ Composition Investigations) takes a hands-off approach: Shoot rocks with a laser and analyze the resulting puff of dust. The Mars Curiosity rover uses that technique, but the density of Venus’ atmosphere might make the results harder to understand. The team is testing the technique in a Venus simulation chamber at Los Alamos National Laboratory in New Mexico.
“We’re convinced it will work,” says VICI principal investigator Lori Glaze at NASA Goddard. “We just need to do some more work to convince the rest of the community.”
There’s hope on the horizon, if Venus explorers can shrink their ambitions. Last year, NASA established a program called Venus Bridge to see if any missions to Venus can fly for $200 million or less. That figure is less than half the cost — and in some cases much less than half — of recently proposed missions.
“I’m a strong believer that constraints breed innovation,” Zurbuchen says, adding that advances in technology mean there are ways to explore that didn’t exist a decade ago. “If you put a financial constraint on it, great missions can happen.”
It would be hard to make meaningful headway on science questions for that little, Dyar notes. “The Venus community is torn,” she adds. But it may take multiple piecemeal missions to understand Venus anyway. “We’ll get the frosting on one trip and the cake on a different trip.”
In the meantime, the Venus hopefuls soldier on.
“My new favorite saying for the Venus community is, ‘Never give up, never surrender,’” Glaze says. “We keep trying.”
It’s a wonder we have chocolate at all. Talk about persnickety, difficult flowers.
Arguably some of the most important seeds on the planet — they give us candy bars and hot cocoa, after all — come from pods created by dime-sized flowers on cacao trees. Yet those flowers make pollination just barely possible.
Growers of commercial fruit crops expect 50 to 60 percent of flowers to make a fruit, or pod, says Emily Kearney of the University of California, Berkeley. In some places, cacao crops manage to be that prolific. But worldwide norms run closer to 15 to 30 percent. In the traditional Ecuadorian plantings that Kearney studies, cacao achieves a mere 3 to 5 percent pollination.
The first sight of a blooming cacao tree (Theobroma cacao) can be “disconcerting,” Kearney says. That’s because most flowers come directly out of the trunk, rather than sprouting from branches as in many other trees. For cacao, special trunk pads burst into little pale constellations of five-pointed starry blossoms. Some trunks, says Kearney, “are completely covered with flowers.” Those flowers make nothing easy. Each petal curves into a tiny hood that fits down around the male, pollen-making structure. A honeybee trying to reach the pollen would be a useless, giant blimp. Instead, flies not much bigger than a poppy seed, in the biting midge subfamily Forcipomyiinae, crawl up into the hoods and do — something.
But what? The flower offers no nectar for the midges to collect. So far, researchers haven’t even demonstrated that there’s an odor luring in the midges. Some biologists have mused that red spikes on the flowers offer nutritious nibbling for midges, but Kearney knows of no tests of this notion.
Another hitch: 100 to 250 grains of pollen are required to fertilize the 40 to 60 seeds that will make up a cacao pod (resembling a wrinkled, swollen cucumber in shades of purple, yellow or orange). Yet midges typically emerge from a flower hood dappled with just a few to 30 grains of the sticky white stuff. What’s more, the midge, dusted with that little bit of pollen like “clumpy sugar,” Kearney says, can’t just hike over to the same bloom’s female part, like a white-bristled paintbrush encircled by red spikes. Pollen is useless for fertilizing any blooms on the tree it came from or on really close relatives. “If we want to get answers about the cacao pollination system,” Kearney says, “I think it’s the wild individuals that are going to open up the field,” instead of cultivated cacao.
The trees evolved in the Amazon Basin and a northern bit of the South American Pacific coast. There, they often grow in clusters of siblings that a monkey unintentionally planted when sucking pulp from a pod and dropping the seeds.
To Kearney, those frail midges seem unlikely to fly the distance from too-close sibling clusters to unrelated trees that offer better cross-pollination chances. So she wonders: Could the cacao with its coy reproductive system have a clandestine, strong-flying native pollinator species that scientists just haven’t noticed?
In 2015, massive wildfires burned through Indonesia, sending thick smoke and haze as far as Thailand.
These fires were “the worst environmental disaster in modern history,” says Thomas Smith, a wildfire expert at King’s College London. Smith estimates that the fires and smoke killed 100,000 people in Indonesia and neighboring countries and caused billions of dollars in damage. The fires were costly for the rest of the planet, too: At their peak, the blazes belched more climate-warming carbon dioxide into the atmosphere each day than did all U.S. economic activity.
Two years later and 13,000 kilometers away, a fire smoldered on the fringes of a barren, northern landscape. The remote blaze could have gone unnoticed. But Jessica McCarty and other fire researchers actively monitor satellite imagery of Earth the way some people check Facebook. One Sunday in August, McCarty, of Miami University in Ohio, was surprised to see massive plumes of what appeared to be white smoke over a swath of Greenland. The giant landmass had not been on her fire radar. It’s mostly ice, and the parts that aren’t have sparse vegetation.
The settings of these two blazes couldn’t have been more different, but scientists suspect the two had something important in common: plenty of decaying organic matter known as peat. Peatlands — which include bogs, other swampy wetlands and, yes, Greenland’s icy soil — are ecosystems rich in decayed organic matter.
In their healthy, soggy state, peatlands are quite fire resistant. So when it comes to fire risk, peat-heavy landscapes haven’t historically gotten the same attention as, say, the dry pine forests of the western United States. But with those devastating peat fires in Indonesia, the spotlight has turned to the planet’s other peatlands, too. Worldwide, peatlands store massive amounts of carbon in thick blankets of wet organic matter accumulated in the ground over centuries. And though they cover just 3 to 5 percent of Earth’s land surface, peatlands store a quarter of all soil carbon. That adds up to more carbon than all of the world’s forests combined.
But changes in land use — draining the water to plant acres of crops that demand drier soil, a common practice in tropical regions, or building a road through an area — can dry out the peat. And then, a single carelessly tossed cigarette or an errant lightning strike can ignite a fire that will smoke and smolder for months, releasing thousands of years of stored carbon as carbon dioxide into the atmosphere.
Or fires set to clear land for agriculture can get out of hand, like they’ve done in Indonesia: Over the last few decades, the country has drained many of its peatlands to grow oil palms and other crops. Now, the country is seeing the worst-case scenario of what can happen when peatlands are disrupted and desiccated. In northern latitudes, meanwhile, thawing permafrost exposes peat that has been buried for years, which can fuel fires like those seen in Greenland last summer. In the short term, peat fires clog the air with deadly smoke and smog. In densely populated areas such as Indonesia, blazes can devour homes and businesses and claim lives. But the fires’ impact lingers long after the flames die down. Peat fires reshape entire ecosystems. Once the peat burns away, it can take thousands of years to build up again. And all of the carbon that was once neatly stored away is instead floating around in the atmosphere, contributing to climate change much like burning coal does.
Now, scientists are trying to get a better handle on peatlands and the effects of agriculture, development and a climate that’s shifting toward warmer and drier. Recent discoveries of hidden peatlands in Africa and South America expand the extent of peat around the world, and up the stakes for protecting those carbon stores. New research is making it increasingly clear that, without a shift in approach, humans might strip away healthy peatlands and get, in return, a lot of climate-warming carbon dioxide. Meet peat Bogs don’t conjure warm, fuzzy feelings for most people. The landscapes are often associated in popular culture with witches, Europe’s mummified “bog bodies” and dreary weather. It’s perhaps telling that “quagmire” — another word for a bog — is also used to refer to a sticky predicament. But to the scientists who study them, bogs are far from bleak.
“Most people walk far, far out of their way to avoid walking through these things, but I love them,” says Merritt Turetsky, a peat researcher at the University of Guelph in Canada. The bogs that she studies in Canada and Alaska look like “hobbit ecosystems,” she says, with all of the action happening low to the ground: stunted trees studding a colorful carpet of mosses and lichens. And, she points out, bogs play a crucial role in keeping our planet healthy.
Carbon is constantly being recycled throughout the world: It’s taken in by plants as carbon dioxide, for example, and is dissolved in the oceans. But excess circulating carbon can throw ecosystems out of whack. Too much carbon dioxide in the atmosphere makes the planet heat up; too much dissolved in the ocean makes the water more acidic. Long-term carbon stores in ocean sediments and rocks such as limestone pull carbon out of the short-term cycle, cloistering it where it can’t do harm. The same goes for peatlands; dig down many meters into a bog, and you’ll find carbon that’s been buried for thousands of years.
And while the untrained eye might look at a bog and see nothing but a soggy morass that calls for waterproof waders, peatlands can be surprisingly diverse. In the tropics, where swamp forests are filled with large, leafy trees, blankets of peat are typically built up by decayed woody plants. Temperate peatlands, like those in the northern United States and Canada, sport scrubbier vegetation and are made mostly from decayed sphagnum moss. Peat is “not exactly nonrenewable, but it accumulates so slowly,” Turetsky says. “A fire can burn through a dry bog and literally release thousands of years of carbon in a couple minutes of combustion.” She learned that firsthand as a graduate student.
Almost 20 years ago, she buried small bags of peat in a Canadian bog to study their decomposition. When she returned two years later to dig up the samples, her entire field site had gone up in smoke. Her precious data were gone.
“I was devastated for about a day,” Turetsky says. “But then I started thinking about it: We were shocked that this system had burned.”
The very next day, she started collecting new data, this time observing how the bog recovered from the fire. Back then, she says, people assumed that the only thing slowing down the accumulation of peat was its inevitable natural decomposition over time. “It was the first time I realized that decomposition wasn’t the only process leading to peat loss,” Turetsky says. “Fire also reduces peat by combusting it.”
Hidden deposits With an increased awareness of the threats to bogs has come a greater push to identify and protect the resources contained in these ecosystems. Recently, large new peat-rich spots have been discovered around the world. In January 2017, British and Congolese scientists announced in Nature that huge tracts of peat have been hiding in a lush expanse of forest straddling the equator in the Central Congo Basin. The area is home to groups of indigenous people but difficult for outsiders to access, so nobody had surveyed its peat resources until recently. The researchers, led by Simon Lewis and Greta Dargie of University College London and the University of Leeds in England, trekked into the basin to extract “cores” to measure how deep the peat went in dozens of places. Based on those long cylindrical cross sections of soil, the researchers calculated that the peat deposits found in the jungle, some as deep as 5.9 meters, boost the global estimated amount of peat in the tropics by 36 percent. Then the team used satellite data to measure the boundaries of the peat. From there, the researchers estimated that the carbon stored in Central Congo Basin’s peat is equivalent to about 20 years of fossil fuel emissions from the United States, at current rates.
Other groups have quantified existing peatlands remotely. A study published in August 2017 in Global Change Biology used data on where water accumulates and how it flows across the landscape to predict where peat might be hiding in tropical regions.
The analyses suggest that South America may be home to far more peat than previously known. A network of smaller peatlands in the Amazon Basin adds up to 629,000 square kilometers, an even larger area than the Congo find, says study coauthor Louis Verchot of the International Center for Tropical Agriculture in Cali, Colombia. This newfound South American peat plus the Congo area and some new finds in Asia boost known tropical peatlands from 440,000 square kilometers to 1.5 million.
Logging and mining already threaten the carbon stored in the trees of tropical forests. The peat-rich soil has value as well. Out of balance When dug up, peat is inherently flammable and is used in some places as a source of fuel. But in their natural, wet state, peatlands are resistant to fires. Even after months of drought, healthy peatlands stay moist. So scientists are trying to understand what factors change that dynamic — and what that means for fires and carbon storage.
It can be hard to test the effect of drying over time in a controlled way, but in one instance, Turetsky got lucky. In 1983, part of a fen, or marshland, in Alberta, Canada, was drained for a forest management project. The water table dropped roughly a quarter of a meter, a moderate amount. Eighteen years later, a wildfire burned in the area.
Turetsky and colleagues saw an opportunity for a natural experiment to answer a few open questions. The researchers tracked how drainage followed by fire affected the peatland over time, compared with areas that burned but weren’t drained or parts that were drained but didn’t burn.
The drained area was far more vulnerable than the undrained area to big changes after a fire, the researchers reported in 2015 in Scientific Reports. The combination of drainage and wildfire invited different plant species to move in over the next decade. The new plants changed the ecosystem from fire-resilient to one that was liable to burn again and again. And the leafy canopy of the broadleaf trees that took up residence in place of the once-dominant black spruces blocked out the sunlight necessary for peat-producing mosses to return. The change Turetsky saw, from a fairly modest disturbance, was much bigger than she expected. She knew that completely drying out such a landscape would make it extremely fire-vulnerable — dramatic changes like those seen in Southeast Asia. But the change in the Alberta fen was much smaller, and yet still had a substantial effect.
Compared with areas that hadn’t been drained, the areas that had been drained lost almost 500 more years’ worth of accumulated peat, she says. (She calculated the figure based on the amount that burned and the rate at which peat accumulates.) That’s 500 additional years of locked-away carbon released back into the atmosphere in a matter of weeks.
Farming’s future Draining the land plus “slash and burn” techniques to clear areas for agriculture are the main reasons that tropical peatlands are catching fire, says Alexander Cobb, an environmental scientist at the Singapore-MIT Alliance for Research and Technology. To make room for oil palm plantations and other crops, companies will raze existing trees (the source of future peat) and drain the water to dry out the soil.
In 2017, 139 scientists signed a letter to the editor in Global Change Biology arguing that draining tropical peatlands for agriculture is unsustainable. Denying the effects that agriculture has on these landscapes will have long-term consequences, such as more frequent and more devastating fires, the researchers wrote.
Now, Indonesia is working to restore its peatlands. It’s not as simple as prohibiting crops in peat-rich areas, though. In densely populated island nations, space is at a premium and people still need to eat, says Susan Page, a tropical bog expert at the University of Leicester in England and one of the letter’s signers. Solving the problem might require finding crops that can grow in soggier soil so bogs wouldn’t have to be drained. But solutions are a long way off.
“A lot of the economic support for alternative crops doesn’t really exist yet,” Page says. “We’re in the in-between stage of knowing we want crops but not having a suitable list of species.”
Even in places where peatlands are protected from agriculture, there are other potential threats. Cobb and colleagues spent months figuring out how to bushwhack through dense trees with exposed roots as tall as a human to reach a rare, untouched peatland in Brunei, a small, wealthy Southeast Asian nation that Cobb says has been more proactive about protecting its peatlands than neighboring countries. The researchers plunged measuring devices into the soil to determine the depth of peat and how wet it was. With those data, the team created a model of the way rainfall affects the amount of peat that can build up in any particular place, published last June in Proceedings of the National Academy of Sciences.
The conclusion: Along with total rainfall, timing of that rainfall matters. If rainfall becomes more irregular, as it’s predicted to in the future, “then with the same average rainfall, the peatland can support less peat,” Cobb says. Safe if frozen Peatlands in cold places face challenges in a changing climate, too. In northern latitudes, including the Arctic, peat has been entombed for centuries in permafrost. Arctic warming is now exposing that peat, raising the risk of once-uncommon fires.
Last summer’s Greenland fire is one such example. When McCarty spotted what she thought was a fire, she posted the satellite data on Twitter. Over the coming weeks, she and other scientists virtually checked in on the fire multiple times each day, becoming convinced that the smoke was fueled by peat.
For one thing, there’s very little vegetation in the region that could provide fuel. Peat in the soil was one of the few options. Plus, the fire lingered for several weeks, but barely traveled. That’s very characteristic of a peat fire, McCarty says. If the fire’s not moving, it’s probably smoldering, slowly burning through dense organic matter with a lot of smoke and minimal flames.
Scientists have not scoped out the Greenland fire site in person, says Guillermo Rein, a fire scientist at Imperial College London. But he’s part of a team that’s trying to organize an expedition to the remote area, to study the soil and confirm that peat was the fire’s main driver.
Arctic peat has what Rein calls “dormant flammability.” That is, when it’s frozen, it’s safe. But if the permafrost begins to thaw, these long-entombed carbon stores are exposed to the air and suddenly vulnerable to burning.
It would be easy to dismiss the Greenland fire as a one-off event, a fluke. But really, it’s just one match in a whole box. Peat blazes have been recorded in Alaska and Siberia, as well as across Canada. Evidence suggests that fires like these will become more common. The National Oceanic and Atmospheric Administration’s annual Arctic Report Card, released December 12, showed that ground-level air in the Arctic is warming twice as fast as the global average surface air temperature. By the end of this century, carbon release from Arctic burning is likely to quadruple, according to a 2016 study in Environmental Research Letters. Plus, fires and permafrost thaw can start a feedback cycle that hastens future thawing, McCarty says.
The precise long-term consequences of such thawing on peat stores in the Arctic are still unclear. While peat emerging from frozen permafrost initially dries and cracks, the area might eventually flood and rewet as ice melts elsewhere, according to a 2015 paper in Scientific Reports. But until then, the dried-out peat is a fire risk.
These Arctic and high-latitude peat fires might not immediately affect as many people as tropical peat fires, because for the most part the fires aren’t in agricultural hot spots or urban centers. But the global consequences, in terms of carbon release, could be just as severe.
Some researchers expect that as climate change pushes agriculture and human populations farther north, “people are going to come more in contact with these mostly pristine landscapes” and disturb them in ways that could increase fire risk, Page says. In Canada, she says, “decades down the line, we could see a similar fire dynamic as we’re seeing in Southeast Asia” — uncontrolled fires causing irreparable damage to long-term carbon stores.
“There’s more and more talk in the north about draining northern soils,” Turetsky adds. “We already know what’s going to happen.”
The sex organs of primitive plants are inspiring precise pipettes.
Liverworts are a group of ground-hugging plants with male and female reproductive structures shaped like tiny palm trees. The female structures nab sperm-packed water droplets by surrounding them with their fronds, like an immobilized claw in an arcade machine.
Scientists have coopted that design to create a plastic pipette that can pick up and transfer precise amounts of water, researchers report March 14 in the Journal of the Royal Society Interface. Normally, the female reproductive structures of the umbrella liverwort (Marchantia polymorpha) clutch the spermy droplets beneath their fronds around the stems. But researchers flipped the umbrella-like cap upside down and stuck it onto a needle so it instead resembled a broom. That rejiggered liverwort could capture a droplet when dipped into water. Tilted at just the right angle, the drop slid back out.
Unlike traditional pipettes, which draw up liquids using suction, the liverwort relies on the surface tension of the water to hold droplets, says study coauthor Hirofumi Wada, a physicist at Ritsumeikan University in Kusatsu, Japan. Wada and his colleagues then 3-D printed plastic structures — varying the overall shape, diameter and number of fronds to adjust how much water the device could grab. Lengthening the fronds to make the water-grabber more spherical enabled it to pick up larger drops, up to a centimeter in diameter.
The invention probably won’t replace the utilitarian workhorse pipettes used in research labs around the world, but could be a low-cost alternative for educational settings, Wada says.
The Red Sea is invading the Mediterranean.… So far about 140 life-forms, mostly animal and mostly invertebrate, have crossed the Isthmus of Suez.… It is possible that this … will result in the loss of a few native fish and invertebrate populations to stiff competition from the newcomers. — Science News, March 30, 1968
Update Whether the movement of creatures through the Suez Canal, called the Lessepsian migration, is good or bad has been debated from the time the waterway opened in 1869. The number of species invading the Mediterranean from the Red Sea now tops 400, scientists estimate. Some of these aliens have an unusual way of making the journey. At least 10 species of foraminifera hitch rides inside the guts of rabbitfish, which defecate out the still-living protists in the Mediterranean. The rabbitfish devour algal forests and the tiny interlopers carpet the seafloor, driving out some native species. In 2015, the Egyptian government widened part of the canal, allowing for more ship traffic — and unwanted invaders.
People who reached what’s now Canada’s Pacific coast around 13,000 years ago made some lasting impressions — with their feet.
Beach excavations on Calvert Island, off British Columbia’s coast, revealed 29 human footprints preserved in clay-based sediment, says a team led by archaeologist Duncan McLaren. About 60 centimeters below the sandy surface, the deposits contained the footprints of at least three individuals, the Canada-based researchers report March 28 in PLOS ONE.
Smudged remains of many more footprints surrounded these discoveries. Ancient people walking on the shoreline apparently trampled those footprints and distorted their shapes, the scientists say. Radiocarbon dating of bits of wood from shore pine trees found in the clay sediment narrowed the age of the footprints from 13,317 to 12,633 years old. Who these footprints belonged to is unknown. Their arrival roughly coincided with the North American appearance of Clovis people, makers of distinctive spearpoints who may have entered the New World via an ice-free, inland route (SN: 5/13/17, p. 8). But stone tools unearthed with the Calvert Island footprints were not made by Clovis people, says McLaren of the Hakai Institute, a research organization in Heriot Bay, and the University of Victoria.
“This discovery places Clovis-age people on the British Columbia coast, far from a so-called ‘ice-free corridor’ and where no Clovis technology has ever been found,” says archaeologist Jon Erlandson of the University of Oregon in Eugene. A long-standing idea that Clovis people were the first Americans, already challenged by recent finds, “is dead in the water,” he argues. Recent challenges to the Clovis-first proposal include evidence that humans inhabited Florida’s Gulf Coast about 14,550 years ago (SN: 6/11/16, p. 8) and South America as early as 18,500 years ago (SN: 12/26/15, p. 10). A 14,500-year-old child’s footprint has also been unearthed in South America. People disembarking from canoes or other vessels may have created the Calvert Island footprints when preparing to move from an ancient shoreline to drier ground, the researchers propose. No sets of tracks made by individuals walking in any particular direction were found.
“Only an expanded excavation can capture how the track makers were moving,” says biological anthropologist Neil Roach at Harvard University. Patterns in the tracks indicate that people repeatedly walked across Calvert Island’s shoreline, but whether they came to gather food or for some other reason is unknown, Roach adds.
The new discoveries add to evidence that people inhabited Canada’s Pacific coast 14,000 years ago or more, as the last ice age wound down and glaciers retreated from coastal areas. Evidence of mastodon hunting dates to around 13,800 years ago at a coastal site in Washington state.
Some researchers suspect that initial settlers of the Americas came from northeast Asia and traveled down the Pacific coast, making inland forays along the way. Rising sea levels from melting ice sheets presumably submerged coastal campsites of these ancient people, erasing most evidence of them.
Between 14,000 and 11,000 years ago, the sea level was two to three meters lower on Calvert Island than today, McLaren’s group estimates. The researchers looked for archaeological remains at shoreline spots exposed at low tide and underwater at high tide. Excavations in 2014 revealed a suspected human footprint. Continued digging in 2015 and 2016 uncovered 28 more footprints.
Many foot impressions included toe marks, indicating that individuals who made the prints were not wearing shoes. Digital enhancement of a footprint with no clear toe marks showed drag marks made by two toes, apparently while slipping on soft ground.
An unknown killer preying on pigs in China has been identified as a new kind of coronavirus. And like the deadly SARS virus, this one also got its start in bats.
In late 2016, pigs mysteriously started having intense diarrhea and vomiting on farms in China’s southeastern Guangdong province. By May 2017, the disease had killed 24,693 piglets. Tests failed to pin the outbreak, which has since waned, on common pig viruses.
By analyzing samples from sick piglets, researchers pieced together the genetic blueprint of the virus causing swine acute diarrhea syndrome, or SADS. It shares 95 percent of its genetic code with another coronavirus, HKU2, detected in horseshoe bats in 2007. Evidence suggests these two coronaviruses share a common ancestor and that SADS jumped from bats to pigs, researchers report April 4 in Nature. No farm workers tested positive for SADS, so the disease doesn’t appear to infect humans. But the first documented human cases of SARS, or severe acute respiratory syndrome, emerged 100 kilometers from the pig farms hit by SADS. The study adds to evidence that keeping an eye on bat viruses could reduce future viral outbreaks — in pigs and humans.
