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      Pollution mucks up the lungs’ immune defenses over time

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      The lungs’ immune defenses can wane with age, leaving older adults more susceptible to lung damage and severe bouts of respiratory infections. New research reveals one reason why this might happen: Inhaled particulate matter from pollution gunks up the works over time, weakening the lungs’ immune system, researchers report online November 21 in Nature Medicine.

      Air pollution is a major cause of disease and early death worldwide and disproportionately impacts poor and marginalized communities (SN: 7/30/20). Particulate matter — a type of pollution emitted from vehicle exhaust, power plants, wildfires and other sources —  has been tied to health harms including respiratory, cardiovascular and neurological diseases (SN: 9/19/17).

      In the new study, researchers from Columbia University analyzed lung immune tissue from 84 organ donors, ranging in age from 11 to 93 years old. The donors were nonsmokers or had no history of heavy smoking. With age, the lungs’ lymph nodes — which filter foreign substances and contain immune cells — became loaded with particulate matter, turning them a deep onyx, the research team found.

      “If the [lymph nodes] build up with so much material, then they can’t do their job,” says Elizabeth Kovacs, a cell biologist who studies inflammation and injury at the University of Colorado Anschutz Medical Campus in Aurora.

      The lymph nodes are home to an array of immune cells, including macrophages. These cellular Pac-Mans gobble up pathogens and other debris, including the particulate matter. Filled with the pollutant, the macrophages’ production of cytokines, proteins the cells secrete to activate other immune cells, decreased. The cells also showed signs of having a diminished capacity for more gobbling.

      The new study indicates that older people have accumulated so much debris, “they may not be able to accumulate more,” impairing their ability to deal with inhaled material, says Kovacs, who was not involved in the research.

      Pollution “is an ongoing and growing threat to the health and livelihood of the world’s population,” the research team writes. Their work finds that threat includes “a chronic and ubiquitous impact” on respiratory immunity with age. More

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      Tiger sharks helped discover the world’s largest seagrass prairie

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      Scientists have teamed up with tiger sharks to uncover the largest expanse of seagrasses on Earth.  

      A massive survey of the Bahamas Banks — a cluster of underwater plateaus surrounding the Bahama archipelago — reveals 92,000 square kilometers of seagrasses, marine biologist Oliver Shipley and colleagues report November 1 in Nature Communications. That area is roughly equivalent to half the size of Florida.

      The finding expands the estimated global area covered by seagrasses by 41 percent — a potential boon for Earth’s climate, says Shipley, of the Herndon, Va.–based ocean conservation nonprofit Beneath The Waves.

      Austin Gallagher, a marine biologist from ocean conservation nonprofit Beneath The Waves, surveys a seagrass field in the Bahamas Banks.Cristina Mittermeier and SeaLegacy

      Seagrasses can sequester carbon for millennia at rates 35 times faster than tropical rainforests. The newly mapped sea prairie may store 630 million metric tons of carbon, or about a quarter of the carbon trapped by seagrasses worldwide, the team estimates.

      Mapping that much seagrass was a colossal task, Shipley says. Guided by previous satellite observations, he and colleagues dove into the sparkling blue waters 2,542 times to survey the meadows up close. The team also recruited eight tiger sharks to aid their efforts. Similar to lions that stalk zebra through tall grasses on the African savanna, the sharks patrol fields of wavy seagrasses for grazing animals to eat (SN: 1/29/18; SN: 5/21/19, SN: 2/16/17).

      “We wouldn’t have been able to map anywhere near the extent that we mapped without the help of tiger sharks,” Shipley says.

      The team captured the sharks with drumlines and hauled each one onto a boat, mounting a camera and tracking device onto the animal’s back before releasing it. The sharks were typically back in the water in under 10 minutes. The team operated like “a NASCAR pit crew,” Shipley says.

      Researchers had previously suggested tracking seagrass-grazing sea turtles and manatees to locate pastures. But tiger sharks were a smart choice because they roam farther and deeper, says Marjolijn Christianen, a marine ecologist at Wageningen University & Research in the Netherlands who was not involved in the new work. “That’s an advantage.”

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      Camera-equipped tiger sharks like this one helped uncover the world’s largest seagrass bed, penetrating areas too deep or remote for divers.

      Shipley and colleagues plan to collaborate with other animals — including ocean sunfish — to uncover more submarine meadows (SN: 5/1/15). “With this [approach], the world’s our oyster,” he says. More

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      Sharks face rising odds of extinction even as other big fish populations recover

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      After decades of population declines, the future is looking brighter for several tuna and billfish species, such as southern bluefin tuna, black marlins and swordfish, thanks to years of successful fisheries management and conservation actions. But some sharks that live in these fishes’ open water habitats are still in trouble, new research suggests.

      These sharks, including oceanic whitetips and porbeagles, are often caught by accident within tuna and billfish fisheries. And a lack of dedicated management of these species has meant their chances of extinction continue to rise, researchers report in the Nov. 11 Science. 

      The analysis evaluates the extinction risk of 18 species of large ocean fish over nearly seven decades. It provides “a view of the open ocean that we have not had before,” says Colin Simpfendorfer, a marine biologist at James Cook University in Australia who was not involved in this research.

      “Most of this information was available for individual species, but the synthesis for all of the species provides a much broader picture of what is happening in this important ecosystem,” he says.

      In recent years, major global biodiversity assessments have documented declines in species and ecosystems across the globe, says Maria José Juan-Jordá, a fisheries ecologist at the Spanish Institute of Oceanography in Madrid. But these patterns are poorly understood in the oceans.

      To fill this gap, Juan-Jordá and her colleagues looked to the International Union for Conservation of Nature’s Red List, which evaluates changes in a species’s extinction risk. The Red List Index evaluates the risk of extinction of an entire group of species. The team specifically targeted tunas, billfishes and sharks — large predatory fishes that have influential roles in their open ocean ecosystems. 

      Red List Index assessments occur every four to 10 years. In the new study, the researchers built on the Red List criteria to develop a way of tracking extinction risk continuously over time, rather than just within the IUCN intervals.

      Juan-Jordá and her colleagues did this by compiling data on species’ average age at reproductive maturity, changes in population biomass and abundance from fish stock assessments for seven tuna species, like the vulnerable bigeye and endangered southern bluefin; six billfish species, like black marlin and sailfish; and five shark species. The team combined the data to calculate extinction risk trends for these 18 species from 1950 to 2019.

      The team found that the extinction risk for tunas and billfishes increased throughout the last half of the 20th century, with the trend reversing for tunas starting in the 1990s and billfishes in the 2010s. These shifts are tied to known reductions in fishing deaths for these species that occurred at the same time.

      The results are positive for tunas and billfishes, Simpfendorfer says. But three of the seven tunas and three of the six billfishes that the researchers looked at are still considered near threatened, vulnerable or endangered. “Now is not the time for complacency in managing these species,” Simpfendorfer says.

      But shark species are floundering in these very same waters where tuna and billfish are fished, where the sharks are often caught as bycatch. 

      Many open ocean sharks — like the silky shark (Carcharhinus falciformis) (pictured) — continue to decline, often accidentally caught by fishers seeking other large fish.Fabio Forget

      “While we are increasingly sustainably managing the commercially important, valuable target species of tunas and billfishes,” says Juan-Jordá, “shark populations continue to decline, therefore, the risk of extinction has continued to increase.”

      Some solutions going forward, says Juan-Jordá, include catch limits for some species and establishing sustainability goals within tuna and billfish fisheries beyond just the targeted species, addressing the issue of sharks that are incidentally caught. And it’s important to see if measures taken to reduce shark bycatch deaths are actually effective, she says. 

      “There is a clear need for significant improvement in shark-focused management, and organizations responsible for their management need to act quickly before it is too late,” Simpfendorfer says.  More

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      Greenland’s frozen hinterlands are bleeding worse than we thought

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      Sea level rise may proceed faster than expected in the coming decades, as a gargantuan flow of ice slithering out of Greenland’s remote interior both picks up speed and shrinks.

      By the end of the century, the ice stream’s deterioration could contribute to nearly 16 millimeters of global sea level rise — more than six times the amount scientists had previously estimated, researchers report November 9 in Nature.

      The finding suggests that inland portions of large ice flows elsewhere could also be withering and accelerating due to human-caused climate change, and that past research has probably underestimated the rates at which the ice will contribute to sea level rise (SN: 3/10/22).

      “It’s not something that we expected,” says Shfaqat Abbas Khan, a glaciologist at the Technical University of Denmark in Kongens Lyngby. “Greenland and Antarctica’s contributions to sea level rise in the next 80 years will be significantly larger than we have predicted until now.”

      In the new study, Khan and colleagues focused on the Northeast Greenland Ice Stream, a titanic conveyor belt of solid ice that crawls about 600 kilometers out of the landmass’s hinterland and into the sea. It drains about 12 percent of the country’s entire ice sheet and contains enough water to raise global sea level more than a meter. Near the coast, the ice stream splits into two glaciers, Nioghalvfjerdsfjord and Zachariae Isstrøm.

      While frozen, these glaciers keep the ice behind them from rushing into the sea, much like dams hold back water in a river (SN: 6/17/21). When the ice shelf of Zachariae Isstrøm collapsed about a decade ago, scientists found that the flow of ice behind the glacier started accelerating. But whether those changes penetrated deep into Greenland’s interior remained largely unresolved.

      “We’ve mostly concerned ourselves with the margins,” says atmosphere-cryosphere scientist Jenny Turton of the nonprofit Arctic Frontiers in Tromsø, Norway, who was not involved in the new study. That’s where the most dramatic changes with the greatest impacts on sea level rise have been observed, she says (SN: 4/30/22, SN: 5/16/13).

      Keen to measure small rates of movement in the ice stream far inland, Khan and his colleagues used GPS, which in the past has exposed the tortuous creeping of tectonic plates (SN: 1/13/21). The team analyzed GPS data from three stations along the ice stream’s main trunk, all located between 90 and 190 kilometers inland.

      The data showed that the ice stream had accelerated at all three points from 2016 to 2019. In that time frame, the ice speed at the station farthest inland increased from about 344 meters per year to surpassing 351 meters per year.

      The researchers then compared the GPS measurements with data collected by polar-orbiting satellites and aircraft surveys. The aerial data agreed with the GPS analysis, revealing that the ice stream was accelerating as far as 200 kilometers upstream. What’s more, shrinking — or thinning — of the ice stream that started in 2011 at Zachariae Isstrøm had propagated more than 250 kilometers upstream by 2021. 

      “This is showing that glaciers are responding along their length faster than we had thought previously,” says Leigh Stearns, a glaciologist from the University of Kansas in Lawrence, who was not involved in the study.

      Khan and his colleagues then used the data to tune computer simulations that forecast the ice stream’s impact on sea level rise. The researchers predict that by 2100, the ice stream will have singlehandedly contributed between about 14 to 16 millimeters of global sea level rise — as much as Greenland’s entire ice sheet has in the last 50 years.

      The findings suggest that past research has probably underestimated rates of sea level rise due to the ice stream, Stearns and Turton say. Similarly, upstream thinning and acceleration in other large ice flows, such as those associated with Antarctica’s shrinking Pine Island and Thwaites glaciers, might also cause sea levels to rise faster than expected, Turton says (SN: 6/9/22, SN: 12/13/21).

      Khan and his colleagues plan to investigate inland sections of other large ice flows in Greenland and Antarctica, with the hopes of improving forecasts of sea level rise (SN: 1/7/20).

      Such forecasts are crucial for adapting to climate change, Stearns says. “They’re helping us better understand the processes so that we can inform the people who need to know that information.” More

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      Wind turbines could help capture carbon dioxide while providing power

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      Wind turbines could offer a double whammy in the fight against climate change.

      Besides harnessing wind to generate clean energy, turbines may help to funnel carbon dioxide to systems that pull the greenhouse gas out of the air (SN: 8/10/21). Researchers say their simulations show that wind turbines can drag dirty air from above a city or a smokestack into the turbines’ wakes. That boosts the amount of CO2 that makes it to machines that can remove it from the atmosphere. The researchers plan to describe their simulations and a wind tunnel test of a scaled-down system at a meeting of the American Physical Society’s Division of Fluid Dynamics in Indianapolis on November 21.

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      Addressing climate change will require dramatic reductions in the amount of carbon dioxide that humans put into the air — but that alone won’t be enough (SN: 3/10/22). One part of the solution could be direct air capture systems that remove some CO2 from the atmosphere (SN: 9/9/22).

      But the large amounts of CO2 produced by factories, power plants and cities are often concentrated at heights that put it out of reach of machinery on the ground that can remove it. “We’re looking into the fluid dynamics benefits of utilizing the wake of the wind turbine to redirect higher concentrations” down to carbon capture systems, says mechanical engineer Clarice Nelson of Purdue University in West Lafayette, Ind.

      As large, power-generating wind turbines rotate, they cause turbulence that pulls air down into the wakes behind them, says mechanical engineer Luciano Castillo, also of Purdue. It’s an effect that can concentrate carbon dioxide enough to make capture feasible, particularly near large cities like Chicago.

      “The beauty is that [around Chicago], you have one of the best wind resources in the region, so you can use the wind turbine to take some of the dirty air in the city and capture it,” Castillo says. Wind turbines don’t require the cooling that nuclear and fossil fuel plants need. “So not only are you producing clean energy,” he says, “you are not using water.”

      Running the capture systems from energy produced by the wind turbines can also address the financial burden that often goes along with removing CO2 from the air. “Even with tax credits and potentially selling the CO2, there’s a huge gap between the value that you can get from capturing it and the actual cost” that comes with powering capture with energy that comes from other sources, Nelson says. “Our method would be a no-cost added benefit” to wind turbine farms.

      There are probably lots of factors that will impact CO2 transport by real-world turbines, including the interactions the turbine wakes have with water, plants and the ground, says Nicholas Hamilton, a mechanical engineer at the National Renewable Energy Laboratory in Golden, Colo., who was not involved with the new studies. “I’m interested to see how this group scaled their experiment for wind tunnel investigation.” More

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      Landslides shaped a hidden landscape within Yellowstone

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      DENVER — A hidden landscape riddled with landslides is coming into focus in Yellowstone National Park, thanks to a laser-equipped airplane.

      Scientists of yore crisscrossed Yellowstone on foot and studied aerial photographs to better understand America’s first national park. But today researchers have a massive new digital dataset at their fingertips that’s shedding new light on this nearly 1-million-hectare natural wonderland.

      These observations of Yellowstone have allowed a pair of researchers to pinpoint over 1,000 landslides within and near the park, hundreds of which had not been mapped before, the duo reported October 9 at the Geological Society of America Connects 2022 meeting. Most of these landslides likely occurred thousands of years ago, but some are still moving.

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      Mapping Yellowstone’s landslides is important because they can cripple infrastructure like roadways and bridges. The millions of visitors that explore the park each year access Yellowstone through just a handful of entrance roads, one of which recently closed for months following intense flooding.

      In 2020, a small aircraft flew a few hundred meters above the otherworldly landscape of Yellowstone. But it wasn’t ferrying tourists eager for up close views of the park’s famous wolves or hydrothermal vents (SN: 7/21/20, SN: 1/11/21). Instead, the plane carried a downward-pointing laser that fired pulses of infrared light at the ground. By measuring the timing of pulses that hit the ground and reflected back toward the aircraft, researchers reconstructed the precise topography of the landscape.

      Such “light detection and ranging,” or lidar, data reveal details that often remain hidden to the eye. “We’re able to see the surface of the ground as if there’s no vegetation,” says Kyra Bornong, a geoscientist at Idaho State University in Pocatello. Similar lidar observations have been used to pinpoint pre-Columbian settlements deep within the Amazon jungle (SN: 5/25/22).

      The Yellowstone lidar data were collected as part of the 3D Elevation Program, an ongoing project spearheaded by the United States Geological Survey to map the entirety of the United States using lidar.

      Bornong and geomorphologist Ben Crosby analyzed the Yellowstone data — which resolve details as small as about one meter — to home in on landslides. The team searched for places where the landscape changed from looking relatively smooth to looking jumbled, evidence that soil and rocks had once been on the move. “It’s a pattern-recognition game,” says Crosby, also of Idaho State University. “You’re looking for this contrast between the lumpy stuff and the smooth stuff.”

      The researchers spotted more than 1,000 landslides across Yellowstone, most of which were clustered near the periphery of the park. That makes sense given the geography of Yellowstone’s interior, says Lyman Persico, a geomorphologist at Whitman College in Walla Walla, Wash., who was not involved in the research. The park sits atop a supervolcano, whose previous eruptions blanketed much of the park in lava (SN: 1/2/18). “You’re sitting in the middle of the Yellowstone caldera, where everything is flat,” says Persico.

      But steep terrain also abounds in the national park, and there’s infrastructure in many of those landslide-prone areas. In several places, the team found that roads had been built over landslide debris. One example is Highway 191, which skirts the western edge of Yellowstone.

      An aerial image of U.S. Highway 191 near Yellowstone shows barely perceptible signs of a long-ago landslide. But laser mapping reveals the structure and extent of the landslide in much greater detail (use the slider to compare images). It’s one of more than 1,000 landslides uncovered by new maps.

      It’s worth keeping an eye on this highway since it funnels significant amounts of traffic through regions apt to experience landslides, Bornong says. “It’s one of the busiest roads in Montana.”

      There’s plenty more to learn from this novel look at Yellowstone, Crosby says. Lidar data can shed light on geologic processes like volcanic and tectonic activity, both of which Yellowstone has in spades. “It’s a transformative tool,” he says. More

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      Heat waves in U.S. rivers are on the rise. Here’s why that’s a problem

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      U.S. rivers are getting into hot water. The frequency of river and stream heat waves is on the rise, a new analysis shows.

      Like marine heat waves, riverine heat waves occur when water temperatures creep above their typical range for five or more days (SN: 2/1/22). Using 26 years of United States Geological Survey data, researchers compiled daily temperatures for 70 sites in rivers and streams across the United States, and then calculated how many days each site experienced a heat wave per year. From 1996 to 2021, the annual average number of heat wave days per river climbed from 11 to 25, the team reports October 3 in Limnology and Oceanography Letters.

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      The study is the first assessment of heat waves in rivers across the country, says Spencer Tassone, an ecosystem ecologist at the University of Virginia in Charlottesville. He and his colleagues tallied nearly 4,000 heat wave events — jumping from 82 in 1996 to 198 in 2021 — and amounting to over 35,000 heat wave days. The researchers found that the frequency of extreme heat increased at sites above reservoirs and in free-flowing conditions but not below reservoirs — possibly because dams release cooler water downstream.

      Most heat waves with temperatures the highest above typical ranges occurred outside of summer months between December and April, pointing to warmer wintertime conditions, Tassone says.

      Human-caused global warming plays a role in riverine heat waves, with heat waves partially tracking air temperatures — but other factors are probably also driving the trend. For example, less precipitation and lower water volume in rivers mean waterways warm up easier, the study says.

      “These very short, extreme changes in water temperature can quickly push organisms past their thermal tolerance,” Tassone says. Compared with a gradual increase in temperature, sudden heat waves can have a greater impact on river-dwelling plants and animals, he says. Fish like salmon and trout are particularly sensitive to heat waves because the animals rely on cold water to get enough oxygen, regulate their body temperature and spawn correctly.

      There are chemical consequences to the heat as well, says hydrologist Sujay Kaushal of the University of Maryland in College Park who was not involved with the study. Higher temperatures can speed up chemical reactions that contaminate water, in some cases contributing to toxic algal blooms (SN: 2/7/18). 

      The research can be used as a springboard to help mitigate heat waves in the future, Kaushal says, such as by increasing shade cover from trees or managing stormwater. In some rivers, beaver dams show promise for reducing water temperatures (SN: 8/9/22). “You can actually do something about this.” More