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    Climate change is coming for your cheese

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    By affecting cows’ diets, climate change can affect cheese’s nutritional value and sensory traits such as taste, color and texture. This is true at least for Cantal — a firm, unpasteurized cheese from the Auvergne region in central France, researchers report February 20 in the Journal of Dairy Science.

    Cows in this region typically graze on local grass. But as climate change causes more severe droughts, some dairy producers are shifting to other feedstocks for their cows, such as corn, to adapt. “Farmers are looking for feed with better yields than grass or that are more resilient to droughts,” but they also want to know how dietary changes affect their products, says animal scientist Matthieu Bouchon.

    For almost five months in 2021, Bouchon and colleagues at France’s National Research Institute for Agriculture, Food and Environment tested 40 dairy cows from two different breeds — simulating a drought and supplementing grass with other fodder, largely corn, in varying amounts.

    The research team tested climate-adapted diets on cows, like the one seen here, at France’s National Research Institute for Agriculture, Food and Environment.INRAE/Matthieu Bouchon

    The team sampled milk from all cows at regular intervals. Milk’s fatty acid and protein profiles impact cheese formation, melting qualities and nutrition, so the researchers chemically identified distributions of those molecules with a technique called gas chromatography. They also identified beneficial microbes in the milk by making Petri dish cultures.

    They found that a corn-based diet did not affect milk yield and even led to an estimated reduction in the greenhouse gas methane coming from cows’ belching. But grass-fed cows’ cheese was richer and more savory than that from cows mostly or exclusively fed corn. Grass-based diets also yielded cheese with more heart-healthy omega-3 fatty acids and higher counts of probiotic lactic acid bacteria. The authors suggest that to maintain cheese quality, producers should include fresh vegetation in cows’ fodder when it is based on corn. 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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      Ancient rocks reveal when rivers began pouring nutrients into the sea

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      Rivers may have operated on a global scale around 3.5 billion years ago.

      The new find comes courtesy of ancient rocks in China and South Africa. A change in rock chemistry around that time provides the earliest known chemical evidence for the weathering of Earth’s continents and the subsequent delivery of nutrients from land to ocean, geobiologist Kurt Konhauser and colleagues report December 12 in Geology.

      Water chips away at rocks on land, removing minerals and washing them away. “As soon as you get weathering, you’ve got a nutrient influx to the oceans, which can lead to … life thriving in coastal waters,” says Konhauser, of the University of Alberta in Edmonton, Canada. More

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      Another danger looms after the LA fires: Devastating debris flows

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      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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      What leads rivers to suddenly change course?

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      Shifting is in a river’s nature. But when a river breaks free of its channel and carves a new path across the landscape, devastating floods may descend upon communities with little to no warning.

      For decades, researchers have struggled to explain exactly how river channels become primed for such sudden diversions, or avulsions. A study published September 18 in Nature may have finally quelled the debate, showing how two factors work together to stage the rerouting of a river. Building on their findings, the researchers also developed a promising algorithm that can predict the new path of a river that has avulsed. More

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      Squall line tornadoes are sneaky, dangerous and difficult to forecast

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      Meteorologist Thea Sandmael watched the storm close in. It was near enough for her to spot a rotating dome of clouds emerging from its dark underbelly — the quickening of a tornado. By the time the spinning mass was 10 minutes away, Sandmael and her colleagues had shut down their radar instruments and evacuated their post.

      “Just keep going,” she advised her colleague behind the wheel, who was rightly focused on maneuvering their SUV down the remote Alabama road. Following behind was another colleague in a truck carrying their cumbersome radar equipment. Evacuating was a good decision, she reflects: “We were sitting on the west side of the road, and the tornado touched down in our exact location.” More

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      in Space & Astronomy

      A weaker magnetic field may have paved the way for marine life to go big

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      Earth’s magnetic field protects life from harmful cosmic radiation. But sometime between about 590 million and 565 million years ago, that security blanket seems to have been much thinner — with far-reaching effects for the development of life on Earth, researchers suggest.

      A weaker magnetic field could account for the higher levels of oxygen recorded in the Earth’s atmosphere and oceans around that time — and for the ensuing proliferation of macroscopic marine animals, the team reports in the May 2 Communications Earth & Environment. More

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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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      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