Despite being declared the third-hottest year on record, 2025 was a relatively quiet year for climate disasters in the US. No major hurricanes made landfall, while the total number of acres burned in wildfires last year—a way of measuring the intensity of wildfire season—fell below the 10-year average.
But starting this week, the West is experiencing what looks to be a record-breaking heat wave, while forecasting models predict that a strong El Niño event is likely to emerge later this year. These two unrelated phenomena could set the stage for a long stretch of unpredictable and extreme weather reaching into next year, compounding the effects of a climate that’s getting hotter and hotter thanks to human activity.
First, there’s the heat. Beginning this week and heading into next, a massive ridge of high-pressure air will bring record-breaking temperatures to the American West. The National Weather Service predicts that temperature records across multiple states are set to be broken in dozens of locations, stretching as far east as Missouri and Tennessee. The NWS has issued heat warnings for parts of California, Arizona, and Nevada, as well as fire warnings for parts of Wyoming, Nebraska, South Dakota, and Colorado.
“This will be the single strongest ridge we’ve observed outside of summer in any month,” says Daniel Swain, a climate scientist at the University of California Agriculture and Natural Resources.
The other remarkable thing about this heat wave, Swain says, is just how long it’s going to last. “This is not a day or two of extreme heat,” he says. “We’ve already in some of these places been seeing record highs every day for a week, and we expect to see them every day for another at least seven to 10 days.” The later end of March will be much more intense, with temperatures in some places breaking April and May records. “There aren’t that many weather patterns that can result in an 85- or 90-degree temperature in San Francisco, Salt Lake City, and Denver in the same week.”
This late winter heat wave is adding on to an already warm winter in the West—with big implications for the summer. A month ago, snowpack levels across multiple states were at record lows thanks to warmer-than-average temperatures. According to data provided by the Department of Agriculture, snowpack levels were still sitting below 50 percent of average across many Western states. Snowpack is a critical natural reservoir for rivers in the West; between 60 to 70 percent of the region’s water supply in many areas comes from melting snow. Low snowpack is a bad sign for already-stressed rivers like the Colorado, which supplies water for 40 million people in seven states.
The ongoing heat wave, Swain says, will more than likely make conditions even worse. “April 1st is typically the point at which snowpack would be, at least historically, at its peak,” he says. Even if temperatures cool off until summer, these low snowpack levels are also a worrisome sign for the upcoming fire season. Snow droughts like the one the West is experiencing can dry out soil, kill trees, and lessen stream flow: ideal conditions for a wildfire to grow. Meanwhile, the water supply in the Colorado River could drop even lower. States that rely on the river are already facing a political crisis as they attempt to renegotiate water rights; a drought would only up the ante.
Then there’s El Niño. Last week, the National Weather Service announced that there was more than a 60 percent chance of an El Niño event emerging in August or September. Various weather models suggest that this El Niño could be particularly strong. While we likely won’t know for sure until summer, “the fact that [all the models] are moving upwards is worth watching,” says Zeke Hausfather, a research scientist at Berkeley Earth.
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![Scientists Say Some Black Holes Are Born From Other Black Holes
Since LIGO’s Nobel-winning discovery of gravitational waves—ripples in spacetime—the U.S.-based detector has been picking up on hundreds of signals from black hole mergers. And, after a decade of studying gravitational waves, researchers believe a significant fraction of black holes may come from cosmic chain reactions. A recent paper published in Physical Review Letters describes an analysis of 155 pairs of binary black holes, identified by LIGO and its sisters, Virgo and KAGRA, in Italy and Japan, respectively. According to the study, about 14% of merging black holes may be what’s called “second-generation black holes,” or black holes that form from previous mergers of two smaller black holes. This “hierarchical” backstory is vastly different from the textbook version of how black holes emerge from the explosive death of a star. “Overall in the universe, black holes are merging all the time,” Cailin Plunkett, the study’s first author and a graduate student at the Massachusetts Institute of Technology, told MIT News. “Now we’re seeing a relatively consistent picture where there’s a decent percentage of black holes that are coming from this repeated pathway.”
Tracking the invisible Gravitational waves that reach Earth’s detectors typically come from extremely intense events. Over the years, LIGO has picked up some truly perplexing signals. For example, last summer it found the most colossal black hole merger ever—and if that wasn’t wild enough, the black holes that took part in the merger lie within a cosmic “dead zone” for black holes.
This zone refers to a range of black hole masses in which, physically speaking, black holes can’t form through ordinary stellar collapse. From these discoveries, astronomers realized just how little we knew about black holes, which are challenging to investigate directly. In that sense, it was a no-brainer that the ever-growing catalog of LIGO’s gravitational signals would turn up entirely new insights about black holes. “It is increasingly clear, both from individual events and population analyses, that massive black holes exist in [this] range,” the researchers wrote in the latest paper. “These observations have spurred further investigation into mechanisms that can populate this gap.”
A wobbly imprint The latest research represents one such investigation. During mergers, the two black holes spiral toward each other along an orbital plane. When one or both black hole spins are misaligned, the orbital plane can wobble, or “precess,” the researchers explained to MIT News. The degree to which the disk wobbles acts as a parameter from which researchers can measure the masses and spins of the merging black holes. One telling sign of hierarchical mergers is that they’re “lopsided,” meaning one of the pair has a much higher spin and mass than the other. For the study, the team created an analytic model to capture the kind of wobble that would have emerged from second-generation black holes. Around 14% of merging black holes followed this pattern, and the second-generation black holes identified had a very specific range of masses, at around 20 solar masses or 40 solar masses and above. Of mysterious origins To be fair, that might not sound like a whole lot. But it demonstrates that a sizeable portion of known black holes indeed follow this pattern. As for why, the team suspects hierarchical mergers emerge from dense stellar environments. Simply, when multiple neighboring stars die and collapse into black holes, the dense environment can make it easier for those black holes to find each other and merge. That could further lead to the formation of second-generation black holes. Theoretically, this could “repeat potentially ad infinitum, by virtue of the fact that you have a ton of stars and black holes in this really dense environment,” Plunkett said.
But an ensuing mystery concerns those black holes in the 40-and-above regime, which coincides with the aforementioned “death zones” for black hole masses. According to stellar evolution theory, black holes born of supernovas shouldn’t leave any black holes above roughly 45 solar masses, explained Plunkett. “Yet we have seen black holes that are that massive,” she mused. “And the question is: Where did they come from?” For now, it’s hard to say when we’ll get an answer to that question, if ever. But one thing seems to be clear: black holes are a lot weirder than we could ever imagine. #Scientists #Black #Holes #Born #Black #HolesBlack holes,Gravitational wave,LIGO Scientists Say Some Black Holes Are Born From Other Black Holes
Since LIGO’s Nobel-winning discovery of gravitational waves—ripples in spacetime—the U.S.-based detector has been picking up on hundreds of signals from black hole mergers. And, after a decade of studying gravitational waves, researchers believe a significant fraction of black holes may come from cosmic chain reactions. A recent paper published in Physical Review Letters describes an analysis of 155 pairs of binary black holes, identified by LIGO and its sisters, Virgo and KAGRA, in Italy and Japan, respectively. According to the study, about 14% of merging black holes may be what’s called “second-generation black holes,” or black holes that form from previous mergers of two smaller black holes. This “hierarchical” backstory is vastly different from the textbook version of how black holes emerge from the explosive death of a star. “Overall in the universe, black holes are merging all the time,” Cailin Plunkett, the study’s first author and a graduate student at the Massachusetts Institute of Technology, told MIT News. “Now we’re seeing a relatively consistent picture where there’s a decent percentage of black holes that are coming from this repeated pathway.”
Tracking the invisible Gravitational waves that reach Earth’s detectors typically come from extremely intense events. Over the years, LIGO has picked up some truly perplexing signals. For example, last summer it found the most colossal black hole merger ever—and if that wasn’t wild enough, the black holes that took part in the merger lie within a cosmic “dead zone” for black holes.
This zone refers to a range of black hole masses in which, physically speaking, black holes can’t form through ordinary stellar collapse. From these discoveries, astronomers realized just how little we knew about black holes, which are challenging to investigate directly. In that sense, it was a no-brainer that the ever-growing catalog of LIGO’s gravitational signals would turn up entirely new insights about black holes. “It is increasingly clear, both from individual events and population analyses, that massive black holes exist in [this] range,” the researchers wrote in the latest paper. “These observations have spurred further investigation into mechanisms that can populate this gap.”
A wobbly imprint The latest research represents one such investigation. During mergers, the two black holes spiral toward each other along an orbital plane. When one or both black hole spins are misaligned, the orbital plane can wobble, or “precess,” the researchers explained to MIT News. The degree to which the disk wobbles acts as a parameter from which researchers can measure the masses and spins of the merging black holes. One telling sign of hierarchical mergers is that they’re “lopsided,” meaning one of the pair has a much higher spin and mass than the other. For the study, the team created an analytic model to capture the kind of wobble that would have emerged from second-generation black holes. Around 14% of merging black holes followed this pattern, and the second-generation black holes identified had a very specific range of masses, at around 20 solar masses or 40 solar masses and above. Of mysterious origins To be fair, that might not sound like a whole lot. But it demonstrates that a sizeable portion of known black holes indeed follow this pattern. As for why, the team suspects hierarchical mergers emerge from dense stellar environments. Simply, when multiple neighboring stars die and collapse into black holes, the dense environment can make it easier for those black holes to find each other and merge. That could further lead to the formation of second-generation black holes. Theoretically, this could “repeat potentially ad infinitum, by virtue of the fact that you have a ton of stars and black holes in this really dense environment,” Plunkett said.
But an ensuing mystery concerns those black holes in the 40-and-above regime, which coincides with the aforementioned “death zones” for black hole masses. According to stellar evolution theory, black holes born of supernovas shouldn’t leave any black holes above roughly 45 solar masses, explained Plunkett. “Yet we have seen black holes that are that massive,” she mused. “And the question is: Where did they come from?” For now, it’s hard to say when we’ll get an answer to that question, if ever. But one thing seems to be clear: black holes are a lot weirder than we could ever imagine. #Scientists #Black #Holes #Born #Black #HolesBlack holes,Gravitational wave,LIGO](https://gizmodo.com/app/uploads/2026/07/black-hole-hierarchial-mergers-1280x853.jpg)
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