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    20 years after Hurricane Katrina, is the U.S. better prepared? 

    In late August 2005, Hurricane Katrina devastated the U.S. Gulf Coast. The storm cut a deadly swath through Louisiana, Mississippi and Alabama, deluging coastal towns as surges of ocean water swept relentlessly ashore, driven by powerful winds. The sheer force of the surging waters overpowered levees meant to protect low-lying New Orleans from floodwaters; the levees failed, and about 80 percent of the city was inundated.

    In all, the hurricane caused more than 1,800 fatalities, displaced hundreds of thousands of people from their homes and was responsible for about $125 billion in property damage. It’s one of the two costliest Atlantic hurricanes on record, tied with 2017’s Hurricane Harvey. More

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    Useful metals get unearthed in U.S. mines, then they’re tossed

    Many useful metals unearthed from U.S. mines are discarded.

    When mining operations dig for valuable metals, they often exhume ore containing other metals too. These by-product elements are usually treated as waste, but recovering even small fractions could offset the need to import them, researchers report August 21 in Science. For instance, recovering just 1 percent of rare earth elements from this material could replace imports.

    “We’re used to skimming cream off the top,” says Elizabeth Holley, a mining geologist from the Colorado School of Mines in Golden. “We need to be better at recovering more from what we’re using.” More

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    A glacier burst, flooding Juneau. Again. This one broke records

    A glacial outburst has sent floodwaters rushing through the town of Juneau, Alaska, forcing residents to evacuate parts of the state capital. The unusual event, called a glacial lake outburst flood, or GLOF, happened as water spilled out of an ice-dammed lake and gushed downstream through melted tunnels in the underside of a large glacier.

    The people of Juneau have experienced at least one such flood every summer for the last 15 years.

    “It’s a story about glacier change,” says Jason Amundson, a glaciologist at the University of Alaska Southeast in Juneau, who is monitoring the event. The warming climate has caused glaciers here to shrink and separate from one another. That’s left an empty valley along the edge of Mendenhall Glacier, which now fills with rain and meltwater each summer. At some point, the water collects deep enough that its pressure forces an opening under the edge of the glacier — allowing it to escape. More

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    Warm autumns could be a driver in monarch butterflies’ decline

    Toastier fall weather might cause migrating monarch butterflies to wing it and change their flight plans, starting the countdown toward death. 

    Eastern monarchs captured during their autumn migration and exposed to warm temperatures in the lab came out of their usual reproductive hiatus, evolutionary biologist Ken Fedorka and colleagues report August 12 in Royal Society Open Science. Breaking that hiatus means the butterflies will likely die sooner than they normally would.

    “Once you decide to go reproductive, your clock starts ticking,” says Fedorka, of the University of Central Florida in Orlando. More

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    See how aerosols loft through Earth’s sky

    The sky abounds with aerosols, tiny particles with large sway over Earth’s temperature. A new NASA visualization reveals how these airborne particles swirl through the atmosphere.

    The agency’s Goddard Earth Observing System tracks major aerosol types — sulfates, black carbon, dust and sea salt. It combines satellite and ground-based observations with advanced computer simulations to show how aerosols can affect air quality and visibility far from their sources. See where they loft in this visualization spanning August 1 to September 14, 2024. More

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    The mystery of melting sea stars may finally be solved 

    A mysterious disease has been turning sea stars into goo since 2013. Now, there’s a leading suspect behind the killings — a bacterium called Vibrio pectenicida, researchers report August 4 in Nature Ecology & Evolution. Knowing the identity of the killer could help scientists protect both captive and wild populations of sea stars.

    The disease, known as sea star wasting disease, is characterized by twisted arms, lesions and rapid death. One of the worst hit species is the sunflower sea star (Pycnopodia helianthoides), which lost almost 91 percent of its population — over a billion individuals — to repeated outbreaks in 2015, 2018 and 2023. This decline has consequences for ocean ecosystems, as sunflower sea stars are predators that keep sea urchin populations in check. In their absence, sea urchins have mowed down kelp forests, which absorb atmospheric carbon dioxide and support fish, otters, sea lions and other animals.  More

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    A Midwest ‘megaflash’ is the longest lightning on record

    A massive bolt of lightning that lit up the sky from Dallas to Kansas City, Mo., in October 2017 is officially the longest single flash ever recorded.

    A reanalysis of satellite data collected during the storm revealed that this megaflash spanned 829 kilometers and lasted 7.39 seconds, says Michael Peterson, an applied physicist at Georgia Tech in Atlanta. A study describing the event was published online July 31 in the Bulletin of the American Meteorological Society.   More

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    What to know about the extreme U.S. flooding — and ways to stay safe

    July has washed across the United States with unusually destructive, deadly torrents of rain.

    In the first half of the month alone, historically heavy downpours sent rivers in Central Texas spilling far beyond their banks, causing at least 130 deaths. Rains prompted flash flooding across wildfire-scarred landscapes in New Mexico and flooded subway stations in New York City. Roadways in New Jersey turned into rivers, sweeping two people to their deaths as the floodwaters carried away their car. A tropical depression dumped up to 30 centimeters of rain in one day on parts of North Carolina, leading to at least six more deaths. More