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    Polar forests may have just solved a solar storm mystery

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    The strongest solar flare in recorded history burst into Earth’s atmosphere in 1859, bathing both hemispheres in brilliantly colorful aurorae as it wreaked worldwide havoc on telegraph systems. The celestial chaos was broadly witnessed, but lingering physical evidence of that storm, dubbed the Carrington event, has proven stubbornly elusive — until now, researchers report in the March 16 Geophysical Research Letters.

    Ecologist Joonas Uusitalo of the University of Helsinki and his colleagues have identified the first known traces of the Carrington event: atoms of carbon-14 preserved in tree rings in Finland’s far north. Scientists previously hadn’t detected tree ring evidence of this event, although other trees have recorded more powerful solar flares that occurred before modern recordkeeping began, such as in 774 and 993. More

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      Heat waves cause more illness and death in U.S. cities with fewer trees

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      In the United States, urban neighborhoods with primarily white residents tend to have more trees than neighborhoods whose residents are predominantly people of color. A new analysis has now linked this inequity to a disparity in heat-related illness and death, researchers report April 8 in npj Urban Sustainability. 

      Neighborhoods with predominantly people of color have 11 percent less tree cover on average than majority white neighborhoods, and air temperatures are about 0.2 degrees Celsius higher during summer, urban ecologist Rob McDonald of The Nature Conservancy and colleagues found. Trees already prevent 442 excess deaths and about 85,000 doctor visits annually in these neighborhoods. In majority white neighborhoods, trees save around 200 more lives and prevent 30,000 more doctor visits. More

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      ‘On the Move’ examines how climate change will alter where people live

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      On the MoveAbrahm LustgartenFarrar, Straus and Giroux, $30

      Ellen Herdell’s nerves were nearing a breaking point. The fortysomething, lifelong Californian had noticed her home was increasingly threatened by wildfires. After relatives lost their house to a blaze and the constant threat traumatized her 9-year-old daughter, Herdell found herself up at 3 a.m. one night in 2020 searching Zillow for homes in Vermont.

      She’s not alone. Across the United States, people facing extreme fires, storms, floods and heat are looking for the escape hatch. In On the Move, Abrahm Lustgarten examines who these people are, where they live, where climate change may cause them to move and how this reshuffling will impact the country (SN: 5/12/20). More

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      Climate change is changing how we keep time

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      Climate change may be making it harder to know exactly what time it is.

      The rapid melting of the ice sheets atop Greenland and Antarctica, as measured by satellite-based gravitational measurements, is shifting more mass toward Earth’s waistline. And that extra bulge is slowing the planet’s rotation, geophysicist Duncan Agnew reports online March 27 in Nature. That climate change–driven mass shift is throwing a new wrench into international timekeeping standards.

      The internationally agreed-upon coordinated universal time, or UTC, is set by atomic clocks, but that time is regularly adjusted to match Earth’s actual spin. Earth’s rotation isn’t always smooth sailing — the speed of the planet’s spin changes depending on a variety of factors, including gravitational drag from the sun and the moon, changes to the rotation speed of Earth’s core, friction between ocean waters and the seafloor, and shifts in the planet’s distribution of mass around its surface. Even earthquakes can affect the spin: The magnitude 9.1 earthquake in Indonesia in 2004, for example, altered the land surface in such a way that it caused Earth to rotate a tiny bit faster, says Agnew, of the Scripps Institution of Oceanography in La Jolla, Calif. More

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      How air pollution may make it harder for pollinators to find flowers

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      Air pollution may blunt the signature scents of some night-blooming flowers, jeopardizing pollination.

      When the aroma of a pale evening primrose encounters certain pollutants in the night air, the pollutants destroy key scent molecules, lab and field tests show. As a result, moths and other nocturnal pollinators may find it difficult to detect the fragrance and navigate to the flower, researchers report in the Feb. 9 Science.

      The finding highlights how air pollution can affect more than human health. “It’s really going deeper … affecting ecosystems and food security,” says Joel Thornton, an atmospheric scientist at the University of Washington in Seattle. “Pollination is so important for agriculture.” More

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      Ancient trees’ gnarled, twisted shapes provide irreplaceable habitats

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      Earth’s oldest, knotted and scarred pine trees are a boon for forest life. 

      These old mountain pines (Pinus uncinata) offer food and shelter for lichens and insects not just because they’re old, but also because of what’s allowed them to grow so old in the first place, researchers report February 5 in the Proceedings of the National Academy of Sciences. The findings highlight the broader importance of big, old trees, and suggest threats to their survival from development, fire or climate change could deliver irreparable harm in certain ecosystems.

      Old growth trees continue to decline around the world (SN: 6/18/18). In Europe, the remaining patches of forest with plentiful old trees constitute just 0.7 percent (or just under 3.5 million acres) of the continent’s forested area. This paper and others like it “are really good, because they show how important old growth is,” says Joseph Birch, an ecologist at Michigan State University in East Lansing who wasn’t involved with the research. This line of work serves as a reminder that we need to have a long-term perspective on old growth trees. “We need to be managing and conserving the forests that we have now, even if they’re younger, so that our descendants in a few hundred or even thousand years can have more old growth on the landscape,” Birch says.

      Ancient mountain pines grow twisted and crooked over their hundreds of years of growth. Dead and decaying parts of the plant, as shown in this tree in Aigüestortes i Estany de Sant Maurici National Park in Catalonia, can serve as habitats for multiple forest species. Ot Pasques

      While the pines’ old age, potentially hundreds of years old, was intriguing to plant physiologist Sergi Munné-Bosch and ecophysiologist Ot Pasques, both at the University of Barcelona, they have also been curious how aging and tree decay affect the broader forest ecosystem, with different life and decay stages providing differing habitat needs to plant, animal and lichen species.

      Prior studies tended to look at how individual trees aged. So Munné-Bosch and Pasques decided up the ante. They studied young, adult and extremely old mountain pines in five different areas of the Spanish Pyrenees mountains. The duo calculated the trees’ ages based on tree trunk girth. (The two traits are correlated, eliminating the need to bore a sample out of the trunk to count tree rings). The team also weighed and measured needles, buds and shoots, analyzed the trees’ tissues for biochemicals linked to stress, decay and growth and noted age-related physical traits in the trees — such as exposed roots, fissured bark and lightning scars. Data on other species living in or on the trees were also recorded. More

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      Here’s how many shark bites there were in 2023

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      Despite the sensationalized portrayal of sharks in movies like Jaws, the ocean’s apex predators have far more to fear from people than vice versa.

      Even though millions of people around the world swim in the ocean each year, just 91 people were bitten by sharks in 2023 and only 10 of those bites were fatal, according to a new report from the Florida Museum of Natural History in Gainesville. Out of all bites, 69 were unprovoked while 22 were provoked, defined as a human-initiated interaction such as trying to touch or feed a shark. These numbers — reported by beach safety officers, hospital staff and other emergency responders — are consistent with the five-year global average. More

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      Cold, dry snaps accompanied three plagues that struck the Roman Empire

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      For those who enjoy pondering the Roman Empire’s rise and fall — you know who you are — consider the close link between ancient climate change and infectious disease outbreaks. 

      Periods of increasingly cooler temperatures and rainfall declines coincided with three pandemics that struck the Roman Empire, historian Kyle Harper and colleagues report January 26 in Science Advances. Reasons for strong associations between cold, dry phases and those disease outbreaks are poorly understood. But the findings, based on climate reconstructions from around 200 B.C. to A.D. 600, help “us see that climate stress probably contributed to the spread and severity of [disease] mortality,” says Harper, of the University of Oklahoma in Norman.   More