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    Fires in the Amazon forest may melt sea ice in Antarctica

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    Soot from forest fires in the Amazon might play a role in the melting of faraway ice in Antarctica.

    For decades, scientists have known that black carbon from burning fossil fuels or forests accelerates ice melt in different parts of the world. According to remote sensing researcher Sudip Chakraborty, the slash-and-burn practices encouraged by Brazil’s former president Jair Bolsonaro, who held office from 2019 to 2023, inspired his team to investigate whether black carbon from the Amazon affected ice melt in Antarctica. More

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      Spotting climate misinformation with AI requires expertly trained models

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      Conversational AI chatbots are making climate misinformation sound more credible, making it harder to distinguish falsehoods from real science. In response, climate experts are using some of the same tools to detect fake information online.

      But when it comes to classifying false or misleading climate claims, general-purpose large language models, or LLMs­ — such as Meta’s Llama and OpenAI’s GPT-4­ — lag behind models specifically trained on expert-curated climate data, scientists reported in March at the AAAI Conference on Artificial Intelligence in Philadelphia. Climate groups wishing to use commonly available LLMs in chatbots and content moderation tools to check climate misinformation need to carefully consider the models they use and bring in relevant experts to guide the training process, the findings show. More

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      A lush, green Arabian Desert may have once linked Africa and Asia

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      The Arabian Desert, today the largest expanse of windswept sand dunes on Earth, experienced recurring periods of humidity millions of years ago, researchers report April 9 in Nature. The study may explain how mammals at that time survived the trek across what is now a vast and barren landscape.

      The findings come from mineral formations deep inside caves beneath the Arabian Peninsula. These speleothems — stalagmites and stalactites, formed by dripping rainwater — provide evidence that the region underwent repeated humid periods stretching back nearly 8 million years. The scientists used uranium dating to precisely determine the ages of speleothem samples, offering one of the oldest climate records for the region. More

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      Solar geoengineering moves into the spotlight as climate concerns grow

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      Earth’s average temperature is continuing to tick inexorably upward as the world’s nations stall at reducing their atmosphere-warming emissions. In the face of that grim future, strategies to try to turn down the planet’s thermostat are gaining traction. One strategy in particular — solar geoengineering, which aims to cool the planet by reflecting solar radiation back into space — may be having a moment in the sun.

      Depending on whom you ask, it’s potentially highly dangerous, highly promising or highly uncertain. There aren’t any real guidelines. But, with the future of emissions restrictions also highly uncertain, some researchers say solar geoengineering needs to be on the table. More

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      The ozone layer shields life on Earth. We’ll soon lose a key way to monitor its health

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      Humankind will soon lose a great deal of vigilance over the ozone layer, which shields life on Earth from harmful solar radiation.

      The impending loss of NASA’s Aura and the Canadian Space Agency’s SCISAT satellites threatens scientists’ ability to closely monitor compounds that destroy ozone and alter stratospheric circulation. With no planned missions to replace either satellite, a data desert in the stratosphere appears imminent, researchers warn in the March Bulletin of the American Meteorological Society. More

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      Splitting seawater offers a path to sustainable cement production

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      A new cement-making process could shift production from being a carbon source to a carbon sink, creating a carbon-negative version of the building material, researchers report March 18 in Advanced Sustainable Systems. This process might also be adaptable to producing a variety of carbon-stashing products such as paint, plaster and concrete.

      Cement production is a huge contributor to global carbon dioxide emissions, responsible for about 8 percent of total CO2 emissions, making it the fourth-largest emitter in the world. Much of that carbon comes from mining for the raw materials for concrete in mountains, riverbeds and the ocean floor. More

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      Some trees are coping with extreme heat surprisingly well

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      Ecologist Akhil Javad felt the thrill of fieldwork quickly fade when he was faced with the prospect of scaling trees over five times his height. But for some of the trees he was studying in India’s Western Ghat mountains, that was the only way to take their temperature.

      So, Javad got climbing. Sensors that he placed on leaves in the upper canopy are providing unprecedented insights into how tropical forests are weathering global warming. The findings suggest that the trees may be in better shape than scientists thought, he and colleagues report in the February Global Change Biology.

      Ecologist Akhil Javad (shown) and colleagues found that tropical trees’ ability to photosynthesize may be more resilient to rising global temperatures than previously thought.Akhil Javad

      In the summer, which lasts from March through June in the region, daily high temperatures in the mountains can cross 37° Celsius and are projected to rise by about 4 degrees Celsius in the next 60 years. That could be a problem for trees, since leaves can get much hotter than the surrounding air.

      As the temperature of a leaf rises, its ability to harness sunlight to make sugar and oxygen becomes less efficient. On average, when leaves surpass 46.7° C, their photosynthetic machinery shuts down, lab studies have shown. When that happens, trees don’t get the energy they need. Many trees in the tropics are already experiencing temperatures beyond that average limit. More

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      Some sea turtles are laying eggs earlier in response to climate change

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      Green sea turtles are adjusting their nesting habits in response to rising global temperatures. Individual females are laying their eggs earlier in the season to cope with warmer conditions, researchers report in the February Proceedings of the Royal Society B.

      Scientists have long known that the sex of most turtle species is determined by incubation temperature — higher temperatures give life to females, and lower ones produce males. As climate change drives up temperatures, more females and fewer males are being born, potentially weakening populations. Extreme heat can also be lethal for the eggs.

      Marine biologist Mollie Rickwood kneels next to a loggerhead turtle protected nest. The females dig themselves down in the sand using their flippers, then they dig a flask-shaped chamber where they lay eggs.Mollie Rickwood

      To understand how turtles are adapting, conservation ecologist Annette Broderick and colleagues analyzed three decades of nesting data from around 600 tagged green turtles (Chelonia mydas) on the beaches of Northern Cyprus. The data included the number of successful hatchlings in each nest and temperatures during incubation. The team found that individual females nested earlier as temperatures rose, laying eggs just over six days earlier, on average, for each 1-degree-Celsius increase.

      This is “the first time anyone looked at individual turtles and looked at how they’re changing,” rather than studying nesting behavior at a population level, says Broderick, of the University of Exeter in England. More

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      Warming is chasing cloud forests steadily uphill

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      Cloud forests are strange and ghostly places — akin to coral reefs hidden high on tropical mountains. Stunted trees loom in the mist, gnarled trunks and branches crusted in moss, lichens, orchids, ferns, bromeliads and even climbing cactus vines. Arboreal frogs and salamanders spawn in fog-fed bromeliad pools, and spider monkeys pause to sip drinks.

      But these enigmatic forests are being squeezed by warming and deforestation.

      Hundreds of tree and plant species that make up Mesoamerican cloud forests are being chased uphill by rising temperatures, at an average rate of 1.8 to 2.7 meters per year, researchers report in the March 7 Science. From 1979 to 2010, these forests retreated 84 meters uphill. At the same time, cattle grazing and deforestation higher on the mountains is pushing the forests downward 6.3 meters per year — squishing these ecosystems into ever narrower bands of territory. More