Aurelia Butler

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    Hotter cities? Here come the rats

    If your city is getting rattier, climate change may be partially to blame.

    In an analysis of 16 cities around the world, those that saw the biggest temperature rises over the years also had more rat complaints over time, researchers report January 31 in Science Advances. Increased urbanization was also connected with more rat reports. The results suggest that higher temperatures may make rats — and the diseases they can spread — even harder to keep at bay. More

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    Another danger looms after the LA fires: Devastating debris flows

    The Los Angeles wildfires were still burning when scientists started scouting the freshly charred burn scars to search for signs of another danger that’s yet to come — roaring torrents of rock and mud and water that can sweep downhill with deadly momentum.

    Triggered by intense bouts of rainfall, these debris flows — as well as flash floods — become more likely to occur after an intense wildfire has scorched an area’s slopes and vegetation. While flash floods can be devastating, debris flows surge with even greater ferocity. At least half of their volume is sediment, and it’s mixed with burned trees, cars and boulders. More

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    Unearthed ice may be the Arctic’s oldest buried glacier remnant

    On a remote island in the Canadian Arctic, researchers have discovered the remains of an ancient glacier that could be over a million years old. The discovery represents what may be the oldest glacier ice ever found buried in permafrost — ground that has been frozen for at least 2 years straight — in the Arctic, researchers report in the January 1 Geology. For researchers keen on studying the glacier, the clock is ticking, as human-caused climate change has exposed the long-preserved ice to melting.

    Like notes in the pages of a logbook, the gas bubbles, compounds and particulates trapped in a glacier’s icy layers can yield information about the atmospheres and climates of bygone millennia. But there are precious few reports of such ice older than the last great expansion of the ice sheets, 26,000 to 20,000 years ago. The newfound ice could thus provide researchers with a rare chance to study the climate of the early Pleistocene epoch, during which the Earth underwent episodic ice ages separated by warm periods known as interglacial periods. “These [Pleistocene climate shifts] are analogs for what we can see in the future,” says geomorphologist Daniel Fortier of the University of Montreal.

    In 2009, Fortier and colleagues were studying a buried fossilized forest on Bylot Island, in Canada’s Nunavut Territory, when they stumbled across the sites of some recent landslides that had been triggered by the thawing of permafrost. The slides had exposed translucent, layered bodies of ice that had been buried a few meters underground, just above the fossil forest. Much to Fortier’s surprise, radiocarbon dating of organic matter in the ice revealed it was over 60,000 years old. “I was not expecting that at all,” he says.

    Researchers are shown digging into the remnant glacier ice, which became exposed by the thawing and slumping of previously frozen ground.Stéphanie Coulombe

    What’s more, in the sediment layers overlying the ice, the researchers discovered a flip in the alignment of magnetic minerals that corresponded with a reversal of Earth’s magnetic field roughly 770,000 years old, indicating the ice was at least that old. And previous research had dated the fossil forest upon which the glacier rested to around 2.8 to 2.4 million years ago, providing a maximum possible age for the ice.

    The discovery is a testament to the resilience of permafrost, Fortier says. While climate projections suggest permafrost will completely thaw in many regions by the end of the century, this preserved glacier has persisted through interglacial periods that were warmer than today, he notes. “I don’t think permafrost will disappear so fast. The system is more resilient than we think.” More

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    A podcast challenges us to reassess our relationship with wildfires

    United by FireDenver Museum of Nature & ScienceAvailable wherever you get your podcasts

    For hundreds of millions of years, wildfires were directed solely by the weather, vegetation and terrain. But in the last century in the United States, people have sought to suppress even those beneficial fires that would otherwise clear out dead vegetation, which can fuel wildfires, and stimulate new growth. Now, catastrophic megafires erupt each year, and in some places, climate change has extended the fire season. Clearly something has to give — our society must change its relationship with fire. More

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    Humans, not climate change, may have wiped out Australia’s giant kangaroos

    The demise of most of Australia’s kangaroo species by 40,000 years ago may have had less to do with climate-caused dietary pressures and more to do with human hunters.

    Dental analyses of ancient kangaroos reveal they weren’t such picky eaters as once thought, researchers report in the Jan. 10 Science. Instead, when it came to climate-related changes in food availability, the animals might have rolled with the punches, the scientists suggest.

    Between 65,000 and 40,000 years ago, more than 90 percent of Australia’s large animal species went extinct. Over half were kangaroos. The primary suspects behind these extinctions were thought to be human hunters, who had arrived sometime between 70,000 and 50,000 years ago, and rapid changes in the climate, which may have dramatically reduced the animals’ dietary options. More

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    California wildfire season should be over. So why is L.A. burning?

    Unusually dry conditions and hurricane-force seasonal winds are fueling multiple fast-moving and destructive wildfires in Los Angeles County. Gusts that reached over 145 kilometers per hour (90 miles per hour) quickly drove the blazes into urban areas, forcing more than 100,000 people to evacuate from their homes and killing at least two people as of January 8.

    The largest of the blazes, known as the Palisades fire, erupted the morning of January 7 on the west side of Los Angeles and has since burned more than 6,400 hectares (15,800 acres) and destroyed around 1,000 structures. The second largest, called the Eaton fire, ignited near Pasadena that night and had burned more than 4,290 hectares by the next morning. A third blaze, the Hurst fire near Sylmar, has burned more than 200 hectares. More

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    More new geckos have been found hiding in Southeast Asia’s limestone towers 

    Landscapes in Southeast Asia once thought to stifle biological evolution may instead stoke its fires.

    Karst ecosystems have been referred to as arks of biodiversity, a term that highlights their biological richness but also implies they merely preserve ancient lineages. These landscapes, with their isolated caves, cliffs and sinkholes, were thought to shelter species from extinction without contributing much to evolution.

    But the discovery over the past several years of nearly 200 gecko species in such regions reveals that karsts are far from stagnant. “They’re not museums, but centers of speciation,” says evolutionary biologist Lee Grismer of La Sierra University in Riverside, Calif.

    Some geckos from the Cyrtodactylus genus, like this newfound one from Cambodia, are uniquely adapted to thrive in the karst landscapes in Southeast Asia. Their specialized bodies allow them to cling to sheer rock faces.L. Lee Grismer

    When Grismer first explored Myanmar’s karst landscapes in 2017, the richness of life hidden within the limestone towers and caves left him stunned. During a 19-day expedition, these ancient rock formations, rising abruptly from the surrounding farmland, revealed geckos so distinct and unexpected that his team identified 12 new species.

    Since then, Grismer and his colleagues have ventured into similar formations across Southeast Asia, delving into the evolutionary secrets they harbor. In early 2024, an expedition to western Cambodia uncovered three new species of bent-toed geckos and a slender gecko — all detailed in upcoming papers — bringing the number of gecko species he has described to around 185. “The biodiversity in these landscapes is just off the charts,” Grismer says.

    The gecko discoveries highlight this dynamism. Many karst-dwelling geckos belong to Cyrtodactylus, the third largest vertebrate genus in the world with close to 400 species described so far. Geckos of this genus discovered by Grismer and his team are among the most recently evolved members of their groups. They exhibit unique adaptations, such as elongated limbs, larger eyes and flatter heads, that enable them to cling to sheer rock faces, much like expert climbers.

    Researchers discovered the Sanpel Cave bent-toed gecko, Cyrtodactylus sanpelensis, in a limestone cave in Myanmar. It was hiding under water running down a stalactite, says evolutionary biologist Lee Grismer. “This has never been observed before,” he says.
    L. Lee Grismer

    Grismer likens the karst formations to islands in an archipelago. Each formation, he says, serves as an evolutionary microcosm, producing species entirely distinct from neighboring karsts. “Species are coming from completely different species groups and different times throughout history.”

    The true extent of gecko diversity in the karsts remains unknown. Grismer and his colleagues have surveyed only about 20 percent of the formations in western Cambodia, and he plans to return there and to Myanmar in 2025. “It wouldn’t surprise me if there are another 200 species out there.” More

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    ‘Forever chemicals’ are causing health problems in some wildlife

    “Forever chemicals” are pervasive, and researchers have in recent years been ringing the alarms about the negative impacts on human health. But humans aren’t the only animals to be concerned about.

    Freshwater turtles in Australia exposed to per- and polyfluoroalkyl substances, or PFAS, experienced changes to their metabolic functions, environmental biochemist David Beale and colleagues report in the Dec. 15 Science of the Total Environment. “We found a whole range of biomarkers that are indicative of cancer and other health problems within reptiles,” says Beale, of the Commonwealth Scientific and Industrial Research Organisation in Dutton Park, Australia. More