Poop contains a lot of valuable scientific information. Researchers can monitor microbes, track enzyme activity or hunt for DNA to gather clues about overall health.
There’s so much one can learn from the waste product that microbiologist Aadra Bhatt at the University of North Carolina at Chapel Hill decided there should be a word for that research — something in the same vein as “in vivo” (research done in living animals) and “in vitro” (research done in a petri dish).
After some linguistic digging, she and two colleagues settled on “in fimo.” The term comes from fimus, one of several Latin words for manure or excrement. Their choice won out over the more obvious option of “in feces” because the word feces doesn’t have the same rich scatological legacy — originally it referred to the dregs in a wine cask, Bhatt says.
She and her colleagues, while already using in fimo at meetings and seminars, published their argument online December 13 in Gastroenterology. Compared with the laborious process of pulling together a scientific paper, coming up with this term was “delightful — and it wasn’t particularly drawn out,” Bhatt says. She hopes the word catches on and gains a place in the lexicon for poopetuity.
SEATTLE — Astronomers have spotted a second repeating fast radio burst, and it looks a lot like the first. The existence of a second repeating burst suggests there could be many more of the mysterious signals in the cosmos.
The burst, called FRB 180814.J0422+73, is one of 13 newly discovered fast radio bursts, or FRBs — brief, bright signals of radio energy that come from distant galaxies. The FRBs were detected over a few weeks last year by the Canadian Hydrogen Intensity Mapping Experiment, or CHIME, in British Columbia. Astronomers reported the discoveries at a meeting of the American Astronomical Society on January 7 and in the Jan. 9 Nature. Most such bursts erupt once, last for a few milliseconds, and are never seen again. So astronomers have puzzled over what causes them for years (SN: 8/9/14, p. 22).
“If you have something that flashes for a millisecond in the sky, and there’s nothing that happens for many years, it’s really hard to study,” says astronomer Shriharsh Tendulkar of McGill University in Montreal, a member of the CHIME team.
But then in 2016, astronomers discovered the first repeating FRB when they realized that a series of bursts all came from a single source, called FRB 121102 (SN: 4/2/16, p. 12). Astronomers tracked the signal to its host galaxy (SN: 2/4/17, p. 10) and determined it was coming from an extremely magnetic environment, such as the region surrounding a black hole (SN: 2/3/18, p. 6). Researchers didn’t know if FRB 121102’s repeating signal was unique. Of the more than 60 FRBs detected, no other was known to repeat — until now. Having spotted a second one, scientists are searching for more.
“Imagine you saw a unicorn,” Tendulkar says. “Then suddenly you discover another one. You know now there is a population of these. There is hope for discovering a lot more.” The CHIME team detected the first of the repeating FRB signals on August 14, with four more coming over the next two months from the same spot on the sky. It wasn’t until the third burst, on September 17, that the team realized they might have a repeater, Tendulkar says.
“Somebody pointed out, hey look, these three bursts seem to have the same properties,” he says. “Everybody got really excited.”
Calculations show that the new repeater is about 1.6 billion light-years away. The CHIME team also saw an odd similarity between the two known repeating bursts. Most FRBs are just a sharp blip, akin to a single note being played on a trumpet. But some of the individual bursts in both repeaters were made up of multiple sub-bursts that descended in frequency, like the “wah wah wah wah” of a sad trombone.
“We’ve seen this in 121102, and we can’t explain it,” says astronomer Emily Petroff of ASTRON, the Netherlands Institute of Radio Astronomy, who was not involved in the new work. “Up until now we’ve only had the one repeater, and it’s given us more questions than answers.” But the fact that both repeaters behave similarly could suggest they have similar origins, she says.
Astronomers may have already caught a third repeating burst, too. FRB 110523, discovered in 2015, has some similar features to the first known repeating FRB, so it was worth checking to see if it also repeats, said astronomer Allison McCarthy of the University of Alabama in Tuscaloosa.
Together with Andrew Seymour of the Green Bank Observatory in West Virginia, McCarthy analyzed more than 41 hours of observations of FRB 110523 taken at the Arecibo Observatory in Puerto Rico. They found one potential repeat burst, McCarthy reported January 9 in a poster at the AAS meeting, but they’re not declaring victory just yet. “It wasn’t strong enough for us to be very sure we had detected one,” McCarthy said, adding that they’re about 60 percent certain. “But it’s still a promising candidate.”
Astronomers’ theories for what causes FRBs are almost as numerous as known FRBs themselves. At one point, astronomers even considered the idea that FRBs could be signals from intelligent aliens. But it’s unclear if the repeating bursts and single bursts both come from the same kinds of sources, or even if one-offs might also repeat if watched for long enough.
“It’s the wild, wild west out there,” Tendulkar says. “We have tantalizing clues, but it’s hard to make definitive conclusions.”
CHIME is likely to catch a lot more of these fast radio bursts. The telescope was still being tested when it caught the 13 new ones, so was not operating at peak performance. “They just barely turned on the telescope,” Petroff says, “and they’re already finding things.”
SAN FRANCISCO — Seizures during sleep can scramble memories — a preliminary finding that may help explain why people with epilepsy sometimes have trouble remembering.
The sleeping brain normally rehashes newly learned material, a nocturnal rehearsal that strengthens those memories. Neuroscientist Jessica Creery and her colleagues forced this rehearsal by playing certain sounds while nine people with epilepsy learned where on a screen certain pictures of common objects were located. Then, while the subjects later slept, the researchers played the sounds to call up some of the associated memories.
This sneaky method of strengthening memories, called targeted memory reactivation, worked as expected for five people who didn’t have seizures during the process. When these people woke up, they remembered the picture locations reactivated by a tone better than those that weren’t reactivated during sleep, said Creery, of Northwestern University in Evanston, Ill. She presented the research March 25 at the annual meeting of the Cognitive Neuroscience Society.
The opposite was true, however, for four people who had mild seizures, detected only by electrodes implanted deep in the brain, while they slept. For these people, memory reactivation during sleep actually worsened memories, making the reactivated memories weaker than the memories that weren’t reactivated during sleep. The combination of seizures and memory reactivation “seems like it’s actually scrambling the memory,” Creery says, a finding that suggests that seizures somehow accelerate forgetting.
A few months back, a new storefront appeared in my small Oregon town. Its shelves were packed with tinctures, jars of salve, coffee beans, bath bombs — even beard oil. This motley collection shared a single star ingredient: CBD.
Produced by the cannabis plant, CBD is the straitlaced cousin of marijuana’s more famous component — the THC that delivers a mind-swirling high. CBD, or cannabidiol, has no such intoxicating effects on the mind. Yet the molecule has captured people’s attention in a profound way, sold as a remedy for pain, anxiety, insomnia and other ailments — all without the high.
That neighborhood shop, CBD Scientific, is far from alone in its efforts to sell people on the benefits of CBD, which is found in both marijuana and hemp, two versions of the Cannabis sativa plant. CBD is popping up in products in pet stores, coffee shops and the health and beauty sections of mainstream grocery stores. It’s even being brewed into beer. I left the shop with a $5 bottle of water infused with “5,000,000 nanograms” of CBD.
So far, messages of CBD’s purported health benefits come from people trying to sell CBD products — not from scientists, says Margaret Haney, a neurobiologist who directs the Marijuana Research Laboratory at Columbia University. A gaping chasm separates the surging CBD market and the scientific evidence backing it. While there are reasons to be excited about CBD, the science just isn’t there yet, Haney says. Scientists still don’t know all of the targets CBD hits in the human body, nor what effects it may have, if any. With the exception of tests in people with rare forms of epilepsy, large studies that compare CBD with placebos in people are rare. Much of the existing research was done with cells in the lab or in lab animals, with results that don’t necessarily translate to people.
And there’s always the chance that for some people, CBD’s magic is made not by the compound itself but by a powerful placebo effect; people who expect good outcomes are more likely to see benefits.
Researchers are stepping into the void, lured by promising early data. Small trials are under way looking at the effect of CBD on anxiety, pain, opioid addiction, depression and other health problems. National Institutes of Health funding for CBD studies went from zero in 2014 to an estimated $16 million in 2018. “We’re very interested in CBD,” says Susan Weiss, director of the Division of Extramural Research at the National Institute on Drug Abuse in Bethesda, Md. Still, she urges caution to people eager to try CBD. Because of lax oversight, there’s no telling what’s inside many of those tinctures, oils, rubs and foods for sale online and in stores. “A lot of the products that people are taking may not be what they think,” she says.
Despite the risks and warnings, it seems safe to say that the collective fascination with CBD isn’t going to wear off anytime soon. “People think it’s great for everything,” says cognitive neuroscientist Kent Hutchison of the University of Colorado Boulder. That can’t possibly be true, he says. “But I do think it’s going to be great for some things. We just need to figure out what those things are.”
Mystery molecule Each morning, Samantha Montanaro of Portland, Ore., drops a CBD tincture under her tongue. “I’m kind of testing out my own body with this,” she says. “I’m finding that it really helps with anxiety and stress.”
Montanaro isn’t alone; CBD testimonials are increasingly easy to find. In 2016, Montanaro, now 35, cofounded Tokeativity, a global cannabis community for women. Back then, “CBD wasn’t even a thing,” she says. But the first sparks of the CBD movement caught fire fast. “It’s been pretty crazy to watch how things have evolved,” she says. Some bullish analysts predict that the CBD market in the United States will balloon from hundreds of millions of dollars in 2018 to almost $20 billion by 2022.
Ziva Cooper directs UCLA’s Cannabis Research Initiative and fields a lot of questions about CBD. Her answers invariably disappoint. “When I tell [people] we don’t have very much evidence in people, they’re actually surprised,” she says. When it comes to CBD’s benefits, “there’s actually very little out there to hang our hats on.”
The one exception is for rare forms of childhood epilepsy. Neurologist Elizabeth Thiele of Massachusetts General Hospital in Boston had a young patient who was having over 100 seizures a day. After other treatments had failed, the boy’s parents began searching for a source of CBD oil, which they desperately wanted to try after learning about promising early results in animals. The family flew to England, so the boy could try the CBD formulation made by GW Pharmaceuticals. The child’s results, Thiele says, were remarkable. After a week of CBD, his daily seizures had fallen to single digits. That result ultimately led to clinical trials, one of which included 171 people, mostly children, with Lennox-Gastaut syndrome, a rare and severe seizure disorder. In addition to their normal medication, half of the participants got doses of CBD that were rigorously tested and standardized by the drug’s maker. The other half received their regular treatment plus a placebo. After 14 weeks, the people taking CBD saw a median drop in monthly seizure frequency of about 44 percent; seizures in people who took the placebo dropped almost 22 percent. Thiele and her colleagues published those results in March 2018 in the Lancet.
Side effects were manageable, the researchers found. Diarrhea, sleepiness, poor appetite and vomiting were more likely to occur in the people who took CBD than in those who got the placebo. Along with results from several other trials, those data were strong enough to prompt the U.S. Food and Drug Administration to approve the CBD drug, called Epidiolex, last June. Despite rigorous testing of Epidiolex, big gaps in knowledge on how the drug works in epilepsy remain. Researchers don’t know how CBD tames seizures. Because the molecule comes from cannabis, the early assumption was that CBD latches onto the same chemical receptors that THC connects to, one primarily in the brain and one mainly on immune cells. It turns out, however, that CBD doesn’t seem to hit either of those receptors.
Instead, studies in rats and mice point to two different targets. One, called TRPV1, is known to play a role in pain sensation and maybe epilepsy, too. The other, called GPR55, might change the activity level of nerve cells in the brain, a feat that may be behind CBD’s antiseizure power.
Scientists also don’t know whether CBD keeps working year after year. For some of Thiele’s patients, CBD seems to still be effective after five years of taking the drug, even allowing them to taper off some of their other medications, she says. But data from 92 other patients, presented in December at the American Epilepsy Society’s annual meeting, suggest that CBD’s benefits can start to fade after about seven months on the drug. About a third of the people in the study needed a dose increase after their CBD doses became less effective, researchers from Tel Aviv Sourasky Medical Center reported.
Research on CBD and other ailments lags way behind the epilepsy work. Early experiments, mostly on lab animals but some in small numbers of people, suggest that CBD might fight anxiety, ease schizophrenia symptoms and address pain.
One example: Healthy men who took CBD before a stressful public speaking task were calmer than those who took a placebo, researchers reported in October in the Brazilian Journal of Psychiatry. But only the 15 men who received doses of 300 milligrams were more relaxed. The 27 who took less or more CBD didn’t see benefits. Other types of studies with people, and studies of mice and rats, have turned up antianxiety effects, too. But most of these studies looked at single doses of CBD, not consistent use.
Early evidence of CBD’s promise against schizophrenia comes from a trial of 88 people with the disorder. After six weeks, people who had received a big daily dose of CBD (1,000 milligrams a day) in addition to their normal medication had more improvements in certain symptoms when compared with people who received a placebo. Those results hint that CBD might be a new type of drug for schizophrenia, researchers wrote in March 2018 in the American Journal of Psychiatry.
Studies in lab animals suggest that CBD may help relieve chronic pain. A study appearing in 2017 in Pain found that CBD could block osteoarthritis pain and nerve damage in rats. Hard data for humans are harder to find, but anecdotes abound. Pain clinician Kimberly Mauer of Oregon Health & Science University in Portland and colleagues at the OHSU Comprehensive Pain Center have seen an uptick in patients who say they’re taking CBD. Their experiences are mixed, she says: “About half the patients say they get some benefit, and about half say they didn’t notice anything.”
No easy access To answer the many outstanding questions about CBD’s effects, scientists need access to the compound. But a complex web of U.S. regulations makes that difficult. CBD is subject to rules from both the FDA and the U.S. Drug Enforcement Administration. CBD produced by the marijuana plant remains on the DEA’s list of the most restrictive class of drugs, Schedule 1, alongside LSD, ecstasy and other drugs deemed to have no accepted medical use and high potential for abuse. Access restrictions on industrial hemp, and by extension, the CBD that comes from hemp, were eliminated in the 2018 Farm Bill, signed into law in December. However, regardless of its provenance, CBD is still subject to FDA regulations, as well as any regulations imposed by states. “As easy as it’s gotten for the average person to go legally to buy recreational marijuana and consume it in many states, it’s gotten harder for scientists,” says Haney at Columbia. One of the few approved sources of CBD is a government-sanctioned cannabis facility at the University of Mississippi in Oxford. After she gets the CBD she needs for her studies, Haney is required to meticulously account for every milligram. “I have a gun safe in a locked room that I get into with my fingerprints to store both cannabidiol and marijuana.”
With those restrictions, many scientists just can’t do the studies they want, Hutchison says. “The whole thing is a little bit crazy. People can sell it everywhere, but it’s very difficult for scientists to study its effects in humans.”
Hutchison and colleagues have figured out a legal work-around that doesn’t require researchers to obtain supplies of CBD. The team is avoiding the government-grown cannabis, which can be quite different from the products in circulation, by testing the effects of the cannabis products that people are actually using. To do this, the researchers created a mobile pharmacology lab they call the CannaVan. The tricked-out Dodge contains equipment to study people after they’ve taken a product containing CBD (or THC) that they bought themselves. The researchers are currently collecting data on CBD’s effects on anxiety and pain. Buyer beware FDA rules say that CBD cannot be legally added to food and sold across state lines, sold as a dietary supplement or marketed with claims of treating diseases. But aside from sending some warning letters, the FDA has, so far, let the marketplace run uninhibited. (Some local health authorities, however, are beginning to flex their might, warning restaurants in New York City, for instance, to take CBD off the menu.)
Overall, no one really knows what’s inside the bottles, rubs and coffees for sale. A study published in 2017 in JAMA gives a sense of the problem. Researchers ordered and tested 84 products sold online in 2016 as CBD-containing products. Of those, only 26 were labeled accurately (containing CBD within 10 percent of the claimed amount); 36 of the products had more CBD than their labels said; and 22 products had less. The researchers also found THC in 18 of the 84 samples. Sophie Cloyd is a 30-year-old manager for the CBD company Ablis of Bend, Ore. She is also pregnant. I met her recently at a ski lodge, where she was offering beverage tastes and describing tinctures, oils and lotions. CBD, she says, has helped her manage this pregnancy, her second. She was prescribed the anti-nausea drug Zofran early in her pregnancy, but “the research on Zofran scared me more than the lack of research on CBD,” she says.
Ablis, which makes CBD-infused fizzy drinks and other products, currently gets purified CBD from Colorado, Cloyd says. When the CBD arrives, the company sends it to an independent lab to confirm that it has the right amount of CBD, no pesticides and no THC. But not all CBD sellers test their products.
An unexpected THC dose might not be enough to get a user high, but it could still be a problem, as news reports have begun to point out. To ease his pain from psoriatic arthritis, a school bus driver in Beaverton, Ore., had been taking a daily dose of CBD oil. In early 2018, he failed a periodic drug test with high THC levels, which caused him to lose his job, Portland news channel KATU reported. Even seemingly small amounts of THC can build up in the body with repeated use.
A product might contain even worse surprises. Between December 2017 and January 2018, for example, 52 people fell ill in Utah, with symptoms such as hallucinations, vomiting and seizures, after taking what they thought was CBD. It turned out that the products, many labeled “Yolo CBD oil,” contained a synthetic cannabinoid, and it had poisoned them.
Even if product labels were always accurate, people have no idea of the correct dose of CBD (assuming the right dose would be effective). “You see it marketed in doses like 10 milligrams,” Hutchison says. “Well, 10 milligrams probably does nothing.” For comparison, people who participated in one Epidiolex study took 20 milligrams per kilogram of body weight. To reach that daily dose, I’d need to chug 254 bottles of that 5 million nanogram CBD water I bought — at a cost of $1,270.
Haney makes the same point: “You’re not getting anything resembling an effective dose when you get CBD added to your coffee, or you buy a mint with a little bit of CBD in it,” she says.
There’s even less known about CBD products that you rub on your skin. Scientists don’t know that CBD in creams, oils and ointments actually makes it into the body. “I’m not convinced that anything you’re rubbing on your body with CBD is even getting through,” Haney says. At its heart, the trouble is that most CBD use isn’t backed up by science, Haney says. “I am not against CBD,” she says. In fact, she is about to start a study looking at CBD to treat nerve pain due to chemotherapy in cancer patients. “But I don’t like marketers determining what it’s good for and what it’s not.”
Hype run amok isn’t anything new, says Mauer, the OHSU pain doctor. Consumers try lots of things before the science is definitive — keto diets, for instance, or vitamin D supplements (SN: 2/2/19, p. 16). And even if it turns out that the chemical doesn’t work, the placebo effect might be enough to help reduce symptoms.
So far, the science on CBD isn’t mature enough to weigh in, one way or another. But judging by the number of studies and clinical trials under way, this nascent research field is growing up fast, seeking to quickly fill the space between the science and what people want to know.
This research boom heartens Montanaro. Her message to the scientific community: “I would encourage curiosity,” she says. “I’m not a doctor, and I’m not a scientist, but I certainly know my own body,” and she says that CBD helps her. From her perspective, science has got some catching up to do.
This story appears in the March 30, 2019 issue of Science News with the headline, “The Allure of CBD: People seek health benefits despite lack of evidence.”
Robot revolution? Educational robots could help students learn new skills and good study habits. But researchers still have a lot to learn about the potential risks involved when young kids keep close company with such robots, Maria Temming reported in “Robots are becoming classroom tutors. But will they make the grade?” (SN: 2/16/19, p. 16).The story reminded reader A. Bogart of Isaac Asimov’s novel The Naked Sun, in which robots and humans live side by side. Asimov “raised the specter of some of the same issues with which scientists are now grappling,” Bogart wrote. Although Asimov had a positive view of science and innovation, all inventions are force multipliers, Bogart noted. “That means they can be used to multiply the effects of good and evil,” Bogart wrote. “Even at this early stage, it is well to think about negative impacts as well as positive ones.” Dogged questions Bone fragments of dogs and other animals unearthed from Shubayqa 6, the site of an ancient settlement in Jordan, suggest that dogs may have helped humans devise new ways of hunting small game around 11,500 years ago, Bruce Bower reported in “Dogs may have helped ancient Middle Easterners hunt small game” (SN: 2/16/19, p. 13).
Reader Eric Hobday took issue with the researchers’ conclusion that dogs assisted with hunting. “I will accept as fact that the bones in Shubayqa show signs of having passed through a dog’s digestive system. However, this in no way indicates that the dog in Shubayqa was any more involved in hunting the animal than my dog was,” Hobday wrote. He suggested that the dogs could have been feral and scavenged villagers’ leftovers. “No evidence of domestication was presented, yet the article says the findings offer new insights into domestication,” Hobday wrote. “Really?”
By comparing bones of modern Afghan hounds, greyhounds, gray wolves and golden jackals, researchers have determined that the Shubayqa 6 bones likely came from domesticated dogs, Bower says. “As pointed out in the story, the presence of numerous dogs at the site fits with observations of modern foragers who use dogs to locate small prey during hunts,” he says. “Reconstructions of ancient behavior are always provisional.” Soil science High demand for sparkling wine may be depleting 400 million kilograms of soil every year from northeastern Italy’s vineyards, Cassie Martin reported in “Prosecco production takes a toll on northeast Italy’s environment” (SN: 2/16/19, p. 5).
“The best wine grows in poor soil conditions,” reader Jonathan Quint wrote. “Is erosion even a concern for a vineyard?”
Soil erosion isn’t necessarily a bad thing. It can help generate new soils to keep an ecosystem healthy. But such a high rate of soil erosion in Italy is a big concern, says Jesús Rodrigo Comino, a geographer at the University of Málaga’s Institute of Geomorphology and Soils in Spain. The current rate is unsustainable and could actually harm vineyards there. A few simple changes, like leaving grass between rows of vines as well as planting hedges around vineyards and vegetation along rivers and streams, might help prosecco vineyards reduce their soil loss, scientists suggest.
On the rise Deaths involving a type of antianxiety medication rose 830 percent from 1999 to 2017 in U.S. women ages 30 to 64, Aimee Cunningham reported in “Overdose deaths tied to antianxiety drugs like Xanax continue to rise” (SN: 2/16/19, p. 12).
Reader Dan Furtado asked if benzodiazepines alone cause overdose deaths. He thought that the drugs, such as Xanax and Valium, could cause an overdose only if a person had additional medical issues or combined the drugs with opioids or similar substances.
“An overdose of benzodiazepines alone can cause death,” Cunningham says. “The drugs depress the central nervous system, so a person who overdoses can stop breathing. But overdose deaths are more likely to happen when benzodiazepines are taken with opioids or alcohol,” she says.
Just beyond the tip of the Antarctic Peninsula lies an iceberg graveyard.
There, in the Scotia Sea, many of the icebergs escaping from Antarctica begin to melt, depositing sediment from the continent that had been trapped in the ice onto the seafloor. Now, a team of researchers has embarked on a two-month expedition to excavate the deposited debris, hoping to discover secrets from the southernmost continent’s climatic past.
That hitchhiking sediment, the researchers say, can help piece together how Antarctica’s vast ice sheet has waxed and waned over millennia. And knowing how much the ice melted in some of those warmest periods, such as the Pliocene Epoch about 3 million years ago, may provide clues to the ice sheet’s future. That includes how quickly the ice may melt in today’s warming world and by how much, says paleoclimatologist Michael Weber of the University of Bonn in Germany. Weber and Maureen Raymo, a paleoclimatologist at Lamont-Doherty Earth Observatory in Palisades, N.Y., are leading the expedition, which set sail on March 25.
“By looking at material carried by icebergs that calved off of the continent, we should be able to infer which sectors of the ice sheet were most unstable in the past,” Raymo says. “We can correlate the age and mineralogy of the ice-rafted debris to the bedrock in the section of Antarctica from which the bergs originated.” Icebergs breaking off from the edges of Antarctica’s ice sheet tend to stay close to the continent, floating counterclockwise around the continent. But when the bergs reach the Weddell Sea, on the eastern side of the peninsula, they are shunted northward through a region known as Iceberg Alley toward warmer waters in the Scotia Sea.
Because so many icebergs from all around the continent converge in one region, it is the ideal place to collect sediment cores and take stock of the debris that the bergs have dropped over millions of years.
“That area in the Scotia Sea is so exciting, because it’s a focus point between South America and the Antarctic Peninsula where the currents flow through, and there are a lot of icebergs,” says Gerhard Kuhn, a marine geologist at the Alfred Wegener Institute in Bremerhaven, Germany. “You get a picture of more or less [all of] Antarctica in that area,” says Kuhn, who has studied the region but is not aboard the current cruise. The expedition, known as leg 382 of the International Ocean Discovery Program, plans to drill at six different sites in the Scotia Sea. At three sites, the team plans to penetrate about 600 meters into the seafloor. “That would likely bring us back to the mid-Miocene, which could translate into 12 million to 18 million years back in time,” Weber says.
At another site, the team plans to drill even deeper, 900 meters, to go further back in time, in hopes of finding sediments that date to the opening of the Drake Passage about 41 million years ago. That passage, a body of water that now lies between South America and Antarctica, opened a link between the Atlantic and Pacific oceans and may have played a role in building up Antarctica’s ice sheets at different times in its history.
A graveyard turned crystal ball How much a melting Antarctica might have contributed to global sea-level rise following the last great ice age, which ended about 19,000 years ago, has been a subject of debate. Seas rose by about 130 meters from 19,000 to 8,000 years ago, Weber says, and much of the melting happened in the northern hemisphere.
But Antarctica may have played a larger role than once thought. In a study published in Nature in 2014, Kuhn, Weber and other colleagues reported that ice-rafted debris from that time period, as recorded in relatively short sediment cores from Iceberg Alley, often occurred in large pulses lasting a few centuries to millennia. Those data suggested that the southernmost continent was shedding lots of bergs much more quickly during those times than once thought.
Now, the researchers want to see even further into the past, to understand how quickly Antarctica’s ice sheet might have melted during even warmer periods, and how much it may have contributed to episodes of past sea-level rise.
The new drilling expedition targets several periods when the climate is thought to have warmed dramatically. One is a warm period in the middle Pliocene about 3.3 million to 3 million years ago, when average global temperatures were 2 to 3 degrees warmer than today; another is the ending of an older ice age about 130,000 years ago, when sea levels rose by about 5 to 9 meters.
Such periods may serve as analogs to the continent’s future behavior due to anthropogenic global warming. Currently, global average temperatures on Earth are projected to increase by between about 1.5 degrees and 4 degrees Celsius relative to preindustrial times, depending on greenhouse gas emissions to the atmosphere over the next few decades (SN: 10/22/18, p. 18).
“The existing [ice core] record from Iceberg Alley taught us Antarctica lost ice through a threshold reaction,” Weber says. That means that when the continent reached a certain transition point, there was sudden and massive ice loss rather than just a slow, gradual melt.
“We have rather firm evidence that this threshold is passed once the ice sheet loses contact with the underlying ocean floor,” he says, adding that at that point, the shedding of ice becomes self-sustaining, and can go on for centuries. “With mounting evidence of recent ice-mass loss in many sectors of West Antarctica of a similar fashion, we need to be concerned that a new ice-mass loss event is already underway, and there is no stopping it.”
For 40 years, they’ve held the front line in Florida’s fight against mosquito-borne diseases. And it turns out that the chickens standing sentinel in cities, marshes, woodlands and residential backyards are clucking good at their job.
Last year, chickens in 268 coops in over a third of Florida’s counties provided scientists weekly blood samples that revealed whether the birds had been bitten by mosquitoes carrying West Nile virus or the Eastern equine encephalitis or St. Louis encephalitis viruses. If a chicken’s blood tests positive for antibodies to one of those viruses, authorities know that the pathogen is circulating. And if enough birds have the antibodies, state officials can ratchet up mosquito-killing measures such as pesticide spraying to help halt disease spread.
The sentinel chicken surveillance programs are “a really good way of monitoring” for certain virus activity, says Thomas Unnasch, a biologist who studies vector-borne diseases at the University of South Florida in Tampa. The birds “are sampling literally hundreds or thousands of mosquitoes every day,” he says. (The chickens can’t keep tabs on dengue or Zika; the mosquitoes carrying those viruses prefer to bite people rather than birds.) In 2018, 833 chickens tested positive for West Nile virus antibodies in Florida, but only 39 people did, according to data from the state’s health department. For Eastern equine encephalitis virus, 154 chickens tested positive in 2018, compared with only three people. Chickens that test positive for the viruses being surveyed don’t transmit them, and people don’t either. Both are considered “dead-end hosts,” meaning that the viral concentration in the blood doesn’t get high enough to infect another mosquito after it bites. Infected cardinals, robins and other backyard birds are the animal reservoirs that help keep the three viruses spreading in the area. Sentinel chickens, by detecting where and when disease-carrying mosquitoes are buzzing, are also providing valuable data on how a virus can spread. Data from 2005 to 2016 revealed that Eastern equine encephalitis virus is active year-round in the Florida panhandle, making the area a source from which the virus moves elsewhere in the state and along the eastern United States, Unnasch and his colleagues report online March 11 in the American Journal of Tropical Medicine and Hygiene.
In people, the viral diseases monitored by the chickens are relatively rare, but can be deadly. The chickens don’t get especially sick, though. “You don’t usually see any symptoms at all,” Unnasch says.
Any chicken whose blood tests positive for the antibodies is removed from the coops since that bird can no longer alert authorities to a new infection. For these chickens, retirement may be spent on a farm, with school or 4-H clubs, or in a backyard coop, depending on the county. The sentinel chicken programs are ready with replacements, raising chicks to supply new birds to signal “where we have a threat to human health,” Unnasch says.
A world-spanning network of telescopes called the Event Horizon Telescope zoomed in on the supermassive monster in the galaxy M87 to create this first-ever picture of a black hole.
“We have seen what we thought was unseeable. We have seen and taken a picture of a black hole,” Sheperd Doeleman, EHT Director and astrophysicist at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., said April 10 in Washington, D.C., at one of seven concurrent news conferences. The results were also published in six papers in the Astrophysical Journal Letters.
“We’ve been studying black holes so long, sometimes it’s easy to forget that none of us have actually seen one,” France Córdova, director of the National Science Foundation, said in the Washington, D.C., news conference. Seeing one “is a Herculean task,” she said. That’s because black holes are notoriously hard to see. Their gravity is so extreme that nothing, not even light, can escape across the boundary at a black hole’s edge, known as the event horizon. But some black holes, especially supermassive ones dwelling in galaxies’ centers, stand out by voraciously accreting bright disks of gas and other material. The EHT image reveals the shadow of M87’s black hole on its accretion disk. Appearing as a fuzzy, asymmetrical ring, it unveils for the first time a dark abyss of one of the universe’s most mysterious objects.
“It’s been such a buildup,” Doeleman said. “It was just astonishment and wonder… to know that you’ve uncovered a part of the universe that was off limits to us.”
The much-anticipated big reveal of the image “lives up to the hype, that’s for sure,” says Yale University astrophysicist Priyamvada Natarajan, who is not on the EHT team. “It really brings home how fortunate we are as a species at this particular time, with the capacity of the human mind to comprehend the universe, to have built all the science and technology to make it happen.” (SN Online: 4/10/19)
The image aligns with expectations of what a black hole should look like based on Einstein’s general theory of relativity, which predicts how spacetime is warped by the extreme mass of a black hole. The picture is “one more strong piece of evidence supporting the existence of black holes. And that, of course, helps verify general relativity,” says physicist Clifford Will of the University of Florida in Gainesville who is not on the EHT team. “Being able to actually see this shadow and to detect it is a tremendous first step.”
Earlier studies have tested general relativity by looking at the motions of stars (SN: 8/18/18, p. 12) or gas clouds (SN: 11/24/18, p. 16) near a black hole, but never at its edge. “It’s as good as it gets,” Will says. Tiptoe any closer and you’d be inside the black hole — unable to report back on the results of any experiments. “Black hole environments are a likely place where general relativity would break down,” says EHT team member Feryal Özel, an astrophysicist at the University of Arizona in Tucson. So testing general relativity in such extreme conditions could reveal deviations from Einstein’s predictions.
Just because this first image upholds general relativity “doesn’t mean general relativity is completely fine,” she says. Many physicists think that general relativity won’t be the last word on gravity because it’s incompatible with another essential physics theory, quantum mechanics, which describes physics on very small scales. The image also provides a new measurement of the black hole’s size and heft. “Our mass determination by just directly looking at the shadow has helped resolve a longstanding controversy,” Sera Markoff, a theoretical astrophysicist at the University of Amsterdam, said in the Washington, D.C., news conference. Estimates made using different techniques have ranged between 3.5 billion and 7.22 billion times the mass of the sun. But the new EHT measurements show that its mass is about 6.5 billion solar masses.
The team has also determined the behemoth’s size — its diameter stretches 38 billion kilometers — and that the black hole spins clockwise. “M87 is a monster even by supermassive black hole standards,” Markoff said.
EHT trained its sights on both M87’s black hole and Sagittarius A, the supermassive black hole at the center of the Milky Way. But, it turns out, it was easier to image M87’s monster. That black hole is 55 million light-years from Earth in the constellation Virgo, about 2,000 times as far as Sgr A. But it’s also about 1,000 times as massive as the Milky Way’s giant, which weighs the equivalent of roughly 4 million suns. That extra heft nearly balances out M87’s distance. “The size in the sky is pretty darn similar,” says EHT team member Feryal Özel. Due to its gravitational oomph, gases swirling around M87’s black hole move and vary in brightness more slowly than they do around the Milky Way’s. “During a single observation, Sgr A* doesn’t sit still, whereas M87 does,” says Özel, an astrophysicist at the University of Arizona in Tucson. “Just based on this ‘Does the black hole sit still and pose for me?’ point of view, we knew M87 would cooperate more.”
After more data analysis, the team hopes to solve some long-standing mysteries about black holes, such as how M87’s behemoth spews a bright jet of charged particles thousands of light-years into space.
This first image is like the “shot heard round the world” that kicked off the American Revolutionary War, says Harvard University astrophysicist Avi Loeb who isn’t on the EHT team. “It’s very significant; it gives a glimpse of what the future might hold, but it doesn’t give us all the information that we want.” Hopes are still high for a much-anticipated glimpse of Sgr A*. The EHT team was able to collect some data on the Milky Way’s behemoth and are continuing to analyze that data, in the hopes of adding its image to the new black hole portrait gallery.
Since the appearance of that black hole changes so quickly, the team is having to develop new techniques to analyze the data. “We’re very excited to work on Sgr A*,” Daniel Marrone, an astrophysicist at the University of Arizona in Tucson, said in the Washington, D.C., news conference. “We’re doing that shortly. We’re not promising anything but we hope to get that very soon.”
Studying such different environments could reveal more details of how black holes behave, Loeb says. “The Milky Way is a very different galaxy from M87.” The next look at the M87 and Milky Way behemoths will have to wait.
Scientists got a lucky stretch of good weather at all eight sites that made up the Event Horizon Telescope in 2017. Then bad weather in 2018 and technical difficulties, which cancelled the 2019 observing run, stymied the team.
The good news is that by 2020, there will be more observatories to work with. The Greenland Telescope joined the consortium in 2018, and the Kitt Peak National Observatory outside Tucson, Ariz., and the NOrthern Extended Millimeter Array (NOEMA) in the French Alps will join EHT in 2020.
Adding more telescopes could allow the team to extend the image, to better capture the jets that spew from the black hole. The researchers also plan to make observations using light of slightly higher frequency, which can further sharpen the image. And even bigger plans are on the horizon: “World domination is not enough for us; we also want to go to space,” Doeleman said.
These extra eyes may be just what’s needed to bring black holes into even greater focus.
Black holes have been beguiling from the very beginning.
Hinted at as early as the 1780s and predicted by Einstein’s general theory of relativity, they didn’t get the name we know today until the 1960s. Bizarre beasts that squash gobs of matter into infinitely dense abysses, black holes were once thought to be merely a mathematical curiosity.
But astronomers tallied up evidence for black holes’ existence bit by bit, puzzling over where these behemoths live, how they gulp down matter and what their existence means for other physics theories.
For more than a decade, a team of researchers has been engrossed in an ambitious effort to snap a picture of a black hole for the very first time. And now they’ve done it. What better time to think back to black holes’ origins and the journey so far?
WASHINGTON — In 2021, wildfires pillaged the world’s carbon-rich snow forests.
That year, burning boreal forests released 1.76 billion metric tons of carbon dioxide, researchers reported March 2 in a news conference at the annual meeting of the American Association for the Advancement of Science.
That’s a new record for the region, which stores about one-third of the world’s land-based carbon. “It’s also roughly double the emissions in that year from aviation,” said earth system scientist Steven Davis of the University of California, Irvine. The trend, if it continues, threatens to make fighting climate change even more difficult. Boreal forests are part of the taiga, a vast region that necklaces the Earth just south of the Arctic Circle. Blazes in tropical forests like the Amazon tend to garner more attention for their potential to contribute large amounts of climate-warming gases to the atmosphere (SN: 9/28/17). But scientists estimate that on a per area basis, boreal forests store about twice as much carbon in their trees and soils as tropical forests.
Climate change is causing the taiga to warm about twice as fast as the global average. And wildfires are growing more widespread in the region, releasing more of the trapped carbon, which in turn can worsen climate change (SN: 5/19/21).
Davis and his colleagues analyzed satellite data on carbon emissions from boreal regions from 2000 to 2021. In 2021, emissions from boreal wildfires made up a whopping 23 percent of all the CO2 emitted by wildfires around the world, the researchers report in the March 3 Science. In contrast, CO2 emissions during an average year from 2000 to 2021 were about 10 percent.
The record-breaking emissions coincided with widespread heat waves and droughts in Siberia and northern Canada, probably fueled by human-caused climate change.
There’s no data yet to show if 2022 saw a similar surge in emissions. But, Davis said, “there’s not actually that much evidence that this record will stand for long.”
