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Ancient people may have survived desert droughts by melting ice in lava tubes
Bands of charcoal from fires lit long ago, found in an ice core from a New Mexico cave, correspond to five periods of drought over 800 years. More
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Ancient humans may have deliberately voyaged to Japan’s Ryukyu Islands
Long ago, ancient mariners successfully navigated a perilous ocean journey to arrive at Japan’s Ryukyu Islands, a new study suggests.
Archaeological sites on six of these isles — part of a 1,200-kilometer-long chain — indicate that migrations to the islands occurred 35,000 to 30,000 years ago, both from the south via Taiwan and from the north via the Japanese island of Kyushu.
But whether ancient humans navigated there on purpose or drifted there by accident on the Kuroshio ocean current, one of the world’s largest and strongest currents, is unclear. The answer to that question could shed light on the proficiency of these Stone Age humans as mariners and their mental capabilities overall.
Now, satellite-tracked buoys that simulated wayward rafts suggest that there’s little chance that the seafarers reached the isles by accident.Sign Up For the Latest from Science News
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Researchers analyzed 138 buoys that were released near or passed by Taiwan and the Philippine island Luzon from 1989 to 2017, deployed as part of the Global Drifter Program to map surface ocean currents worldwide. In findings published online December 3 in Scientific Reports, the team found that only four of the buoys came within 20 kilometers of any of the Ryukyu Islands, and these did so only as a result of typhoons and other adverse weather.
It is unlikely that ancient mariners would have set out on an ocean voyage with a major storm on the horizon, say paleoanthropologist Yousuke Kaifu of the University of Tokyo and colleagues. As a result, the new findings indicate that the Kuroshio current would have forced drifters away from rather than toward the Ryukyu Islands, suggesting that anyone who made the crossing did so intentionally instead of accidentally, Kaifu says.
Geologic records suggest that currents in the region have remained stable for at least the past 100,000 years. So it’s reasonable to conclude that these buoys mimic how well ancient watercraft set adrift in the same area might have fared, the researchers say.
“From a navigation perspective, crossing to the Ryukyus was so challenging that accidental-drift models are unlikely to provide an effective explanation,” agrees archaeologist Thomas Leppard of Florida State University in Tallahassee, who was not involved in the research. This new work “is, of course, not conclusive, but it is suggestive.”
Stone tools and butchered remains of a rhinoceros suggest archaic human lineages such as Homo erectus may have similarly crossed seas at least 709,000 years ago. And artifacts found in Australia suggest modern humans may have begun voyaging across the ocean at least 65,000 years ago (SN: 7/19/17). But it remains hotly debated whether humans’ ocean journeys during the Paleolithic, which lasted from roughly 2.6 million years ago to about 11,700 years ago, were generally made accidentally or intentionally.
Other data do suggest that ancient humans could have deliberately made the voyage to the Ryukyu Islands. In 2019, a team of adventurers succeeded in paddling more than 200 kilometers from Taiwan to Yonaguni in the archipelago using a dugout canoe that Kaifu and his colleagues made using stone axes modeled off Japanese Paleolithic artifacts.
Although the people of the Paleolithic are often perceived as primitive and conservative in their goals, “I feel something very different from the evidence of human presence on these remote islands,” Kaifu says. More - in Heart
Plastics are showing up in the world’s most remote places, including Mount Everest
Minuscule shreds and threads of plastic are turning up all over, including in the snow on Mount Everest.
“We’ve known that plastic is in the deep sea, and now it’s on the tallest mountain on Earth,” says Imogen Napper, a marine scientist at the University of Plymouth in England and a National Geographic Explorer. “It’s ubiquitous through our whole environment.”
Plastic plays an increasingly large role in our lifestyles: Globally, the use of plastics has shot up from around 5 million metric tons in the 1950s to more than 330 million metric tons in 2020. As they’re used and cast away, these plastic products shed tiny particles. The broken-down bits of bags, bottles and other consumer plastics, each smaller than 5 millimeters, can harm animals, such as marine crabs that get plastics stuck in their gills (SN: 7/8/14). They may also mess with ecosystems (SN: 1/31/20).
Here are some of the most extreme places where microplastics have been found.Sign Up For the Latest from Science News
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Atop the world’s tallest mountain
All of the 11 snow samples that Napper’s team analyzed from Mount Everest contained plastic, the researchers report November 20 in One Earth. “I had no idea what the results were going to look like … so that really took me aback,” says Napper.
The highest concentration of microplastics — 119,000 pieces per cubic meter — was in snow from Everest Base Camp, where climbers congregate, but plastic pieces also appeared at a spot 8,440 meters above sea level, near the 8,850-meter summit. The scientists also found plastics in three of eight samples of stream water from Everest. Perhaps the finding should not have been so surprising: Hundreds of people attempt to summit the mountain each year, leaving piles of trash behind. The majority of the microplastics found were polyester fibers, likely originating from climbers’ equipment and clothes.
In the deepest ocean depths
Plastic pollution in the sea goes far deeper than the floating Pacific garbage patch (SN: 3/22/18). Scientists have fished plastic fibers and fragments from the guts of critters dwelling in ocean trenches around the Pacific Rim. Of 90 crustaceans analyzed in a 2019 study, 65 contained microplastics, with the deepest coming from 10,890 meters down in the Mariana Trench. In another study, a sampling of water in the Monterey Bay suggests that plastic debris is accumulating below the surface and is most prevalent at 200 to 600 meters deep (SN: 6/6/19).
Animals are ingesting microplastics in the deepest parts of the sea. In the guts of amphipods (one shown, left) collected from nine sites on the Pacific Rim’s trenches, researchers found plastic fragments, including microfibers (right) found in a critter from 10,890 meters deep in the Mariana Trench.A.J. Jamieson et al/Roy Soc Open Society 2019
Blowing in the wind
Carried through the air, microplastics can make their way to remote areas such as a meteorological station in the Pyrenees Mountains (SN: 4/15/19). On average, an estimated 365 microplastic particles per square meter per day rained down on that site during the study period, about as much as falls from the sky in some cities. Simulations of wind directions and speed suggest the plastic fragments traveled at least 95 kilometers before landing at the site.
Embedded in Arctic ice
A 2018 study reported millions to tens of millions of microplastic pieces per cubic meter from melted Arctic ice cores. The research team identified 17 types of plastic, including some used in packaging materials and others used in paints or fibers. Another 2020 report found lower concentrations for sea ice cores, ranging from 2,000 to 17,000 plastic particles per cubic meter. The 2020 study also found that water beneath ice floes held between 0 to 18 microplastic particles per cubic meter.
In our guts
A 2019 study estimates that an average American consumes between 39,000 and 52,000 pieces of microplastic a year. Researchers came up with this number by drawing on previous studies that had surveyed plastic pieces in tap and bottled water and in certain food items, such as fish, sugar, salt and alcohol. More - in Heart
50 years ago, scientists suspected microbes flourished in clouds
Clouds may be ecosystems — Science News, November 14, 1970
Clouds in the sky may contain living microbial ecosystems…. [Research] determined that metabolic activity, in the form of CO2 uptake into organic material, occurred in [airborne] dust over a 24-hour period, whereas it did not occur in sterilized control dust.
Update
The atmosphere is rich in microbial life. One census documented some 28,000 bacterial species in samples of water from clouds above a mountain in France, scientists reported in 2017. Research building over the last decade or so has supported the claim that some bacteria may indeed be metabolically active within their hazy abodes. One species of Bacillus, for example, eats sugar floating in the atmosphere to build a coating — perhaps to shield itself from ultraviolet radiation and low temperatures (SN: 2/7/15, p. 5). Some scientists suspect cloud bacteria contribute to Earth’s carbon and nitrogen cycles, and even influence weather (SN: 6/18/11, p. 12). The microbes can spur ice crystals to form, triggering rain and snow — and a ride back to Earth’s surface. More - in Heart
Once hurricanes make landfall, they’re lingering longer and staying stronger
Atlantic hurricanes are taking longer to weaken after making landfall than they did 50 years ago, thanks to climate change. Over the past 50 years, increasingly warm ocean waters have juiced up the storms, giving them more staying power after they roar ashore, scientists report in the Nov. 12 Nature. That could potentially extend storms’ destructive power farther inland, the researchers say.
As ocean waters warm, tropical cyclones — called hurricanes in the Atlantic Ocean — are likely to gain in intensity, studies show (SN: 9/28/18). They can also hold more moisture, leading to seemingly unremitting rainfall (SN: 9/13/18). And they may move more slowly, allowing more time to dump that rain on coastal communities. All of this increases the potential hazard on land (SN: 6/6/18).
Once a storm hits land, its energy begins to dissipate. But that relief is coming later than it once did, report physicists Lin Li and Pinaki Chakraborty, both of the Okinawa Institute of Science and Technology in Japan.
Li and Chakraborty analyzed the intensity of historical Atlantic hurricanes over the first 24 hours after landfall. In 1967, a typical storm’s intensity decayed by 76 percent within the first day after landfall. But by 2018, storms were only 52 percent less intense after 24 hours. That trend, the researchers say, aligns with increasing sea-surface temperatures in the Gulf of Mexico and the western Caribbean Sea.
That’s because the intense winds of cyclones feed on moisture and heat picked up from the warm waters, and warmer air can also hold more moisture. So as the oceans heat up, they not only add more moisture, making hurricanes rainier, but also add more heat — like a portable engine the storm uses to fuel its fury for just a bit longer. More - in Heart
With Theta, 2020 sets the record for most named Atlantic storms
It’s official: 2020 now has the most named storms ever recorded in the Atlantic in a single year.
On November 9, a tropical disturbance brewing in the northeastern Atlantic Ocean gained enough strength to become a subtropical storm. With that, Theta became the year’s 29th named storm, topping the 28 that formed in 2005.
With maximum sustained winds near 110 kilometers per hour as of November 10, Theta is expected to churn over the open ocean for several days. It’s too early to predict Theta’s ultimate strength and trajectory, but forecasters with the National Oceanic and Atmospheric Administration say they expect the storm to weaken later in the week.
If so, like most of the storms this year, Theta likely won’t become a major hurricane. That track record might be the most surprising thing about this season — there’s been a record-breaking number of storms, but overall they’ve been relatively weak. Only five — Laura, Teddy, Delta, Epsilon and Eta — have become major hurricanes with winds topping 178 kilometers per hour, although only Laura and Eta made landfall near the peak of their strength as Category 4 storms.Sign Up For the Latest from Science News
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Even so, the 2020 hurricane season started fast, with the first nine storms arriving earlier than ever before (SN: 9/7/20). And the season has turned out to be the most active since naming began in 1953, thanks to warmer-than-usual water in the Atlantic and the arrival of La Niña, a regularly-occurring period of cooling in the Pacific, which affects winds in the Atlantic and helps hurricanes form (SN: 9/21/19). If a swirling storm reaches wind speeds of 63 kilometers per hour, it gets a name from a list of 21 predetermined names. When that list runs out, the storm gets a Greek letter.
While the wind patterns and warm Atlantic water temperatures set the stage for the string of storms, it’s unclear if climate change is playing a role in the number of storms. As the climate warms, though, you would expect to see more of the destructive, high-category storms, says Kerry Emanuel, an atmospheric scientist at MIT. “And this year is not a poster child for that.” So far, no storm in 2020 has been stronger than a Category 4. The 2005 season had multiple Category 5 storms, including Hurricane Katrina (SN: 12/20/05).
There’s a lot amount of energy in the ocean and atmosphere this year, including the unusually warm water, says Emanuel. “The fuel supply could make a much stronger storm than we’ve seen,” says Emanuel, “so the question is: What prevents a lot of storms from living up to their potential?”
On September 14, five named storms (from left to right, Sally, Paulette, Rene, Teddy and Vicky) swirled in the Atlantic simultaneously. The last time the Atlantic held five at once was 1971.NOAA
A major factor is wind shear, a change in the speed or direction of wind at different altitudes. Wind shear “doesn’t seem to have stopped a lot of storms from forming this year,” Emanuel says, “but it inhibits them from getting too intense.” Hurricanes can also create their own wind shear, so when multiple hurricanes form in close proximity, they can weaken each other, Emanuel says. And at times this year, several storms did occupy the Atlantic simultaneously — on September 14, five storms swirled at once.
It’s not clear if seeing hurricane season run into the Greek alphabet is a “new normal,” says Emanuel. The historical record, especially before the 1950s is spotty, he says, so it’s hard to put this year’s record-setting season into context. It’s possible that there were just as many storms before naming began in the ‘50s, but that only the big, destructive ones were recorded or noticed. Now, of course, forecasters have the technology to detect all of them, “so I wouldn’t get too bent out of shape about this season,” Emanuel says.
Some experts are hesitant to even use the term “new normal.”
“People talk about the ‘new normal,’ and I don’t think that is a good phrase,” says James Done, an atmospheric scientist at the National Center for Atmospheric Research in Boulder, Colo. “It implies some new stable state. We’re certainly not in a stable state — things are always changing.” More - in Heart
How frigid lizards falling from trees revealed the reptiles’ growing cold tolerance
After the coldest night in south Florida in a decade, lizards were dropping out of palm trees, landing legs up. The scientists who raced to investigate the fallen reptiles have now found that, despite such graceless falls, some of these tropical, cold-blooded creatures are actually more resilient to cold than previously thought.
The finding sheds light on how some species might respond to extreme weather events caused by human-caused climate change (SN: 12/10/19). Although climate change is expected to include gradual warming globally, scientists think that extreme events such as heat waves, cold snaps, droughts and torrential downpours could also grow in number and strength over time.
The idea for the new study was born after evolutionary ecologist James Stroud received a photo of a roughly 60-centimeter-long iguana prone on its back on a sidewalk from a friend in Key Biscayne, an island town south of Miami. The previous night, temperatures dropped to just under 4.4° Celsius (40° Fahrenheit).
“When air temperatures drop below a critical limit, lizards lose the ability to move,” says Stroud, of Washington University in St. Louis. Lizards that sleep in trees “may lose their grip.” Stunned lizards on the ground are likely easy prey for predators, he notes.Sign Up For the Latest from Science News
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Realizing that the cold snap could be used to study how future instances of extreme weather might affect such animals in the wild, Stroud and colleagues rushed to collect live specimens of as many different kinds of lizards as they could in the Miami area (SN: 8/27/20). The researchers then tested how well the six reptile species they captured tolerated cold by sticking thermometers on the animals, placing them in a large cooler of ice and observing how cold they got before becoming too stunned to right themselves after getting flipped on their backs.
Stroud and colleagues had previously run similar tests on these lizard species as part of research on invasive species. That work in 2016 suggested that the reptiles might not easily withstand cold snaps like the recent one — cold tolerances ranged from as low as about 7.7° C for the Puerto Rican crested anole (Anolis cristatellus) to roughly 11.1° C for the brown basilisk (Basiliscus vittatus).
Some tropical, cold-blooded lizards, such as this brown basilisk (Basiliscus vittatus), are more resilient to cold than previously thought, a new study finds.John Sullivan/iNaturalist (CC BY-NC 4.0)
The new study, however, revealed that the reptiles now could withstand temperatures roughly 1 to 4 degrees C colder. Oddly, the lizards, on average, could all endure cold down to the same lowest temperature, about 5.5° C, the researchers report in the October Biology Letters. Given the great variation in size, ecology and physiology between these species, “this was a really unexpected result,” and one that the researchers don’t have an explanation for, Stroud says.
Natural selection may be behind the change, meaning that abnormally cold temperatures are killing off those individuals that could not survive and leaving behind those that happen to be better able to tolerate cold. Alternatively, the reptiles’ bodies could have changed in some way to acclimate to the colder temperatures. Stroud hopes in the future to measure the cold tolerance of lizards immediately before a forecasted cold snap and then examine the same reptiles immediately afterward to look for signs of acclimation.
Scientists have long thought that tropical species, which have typically evolved in thermally stable environments, might prove especially vulnerable to major shifts in temperature (SN: 5/20/15). This new study reveals a way in which species can either rapidly evolve or acclimate, which “may provide ecosystems with some resilience to extreme climate events,” says Alex Pigot, an ecologist at University College London who did not take part in the research.
One remaining question “is whether this resilience also applies to extreme heating events,” Pigot adds. “Previous evidence has suggested that species’ upper thermal limits may be less flexible than their lower thermal limits.” More - in Heart
Even the deepest, coldest parts of the ocean are getting warmer
Things are heating up at the seafloor.
Thermometers moored at the bottom of the Atlantic Ocean recorded an average temperature increase of about 0.02 degrees Celsius over the last decade, researchers report in the Sept. 28 Geophysical Research Letters. That warming may be a consequence of human-driven climate change, which has boosted ocean temperatures near the surface (SN: 9/25/19), but it’s unclear since so little is known about the deepest, darkest parts of the ocean.
“The deep ocean, below about 2,000 meters, is not very well observed,” says Chris Meinen, an oceanographer at the U.S. National Oceanic and Atmospheric Administration in Miami. The deep sea is so hard to reach that the temperature at any given research site is typically taken only once per decade. But Meinen’s team measured temperatures hourly from 2009 to 2019 using seafloor sensors at four spots in the Argentine Basin, off the coast of Uruguay.
Temperature records for the two deepest spots revealed a clear trend of warming over that decade. Waters 4,540 meters below the surface warmed from an average 0.209° C to 0.234° C, while waters 4,757 meters down went from about 0.232°C to 0.248°C. This warming is much weaker than in the upper ocean, Meinen says, but he also notes that since warm water rises, it would take a lot of heat to generate even this little bit of warming so deep.
It’s too soon to judge whether human activity or natural variation is the cause, Meinen says. Continuing to monitor these sites and comparing the records with data from devices in other ocean basins may help to clarify matters. More
