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Science | The Atlantic

theatlantic.com

From high above, Hurricane Helene’s swirling clouds seem to have taken a piece of the United States and swallowed it whole. Helene, which made landfall last night as a Category 4 storm, has drenched the Southeast from the tip of Florida all the way up to North Carolina. Even though it weakened to a tropical storm this morning, streets have transformed into rivers, dams are threatening to fail, and more flooding is still to come. At least 22 people have died in the Southeast. Millions are without power. Florida’s Big Bend region, where Helene came ashore, had never faced such a strong hurricane in recorded history.Helene arrived during an Atlantic hurricane season that forecasters had predicted would be unprecedented, thanks to record-warm ocean temperatures proffering extra fuel for storms. Since Hurricane Beryl swept over the Gulf Coast in July, the season has been quieter so far than the most dire expectations—but still unusually intense for Americans living in hurricane country. On average, one or two hurricanes make landfall in the U.S. per season. Helene is the fourth to come ashore on the Gulf Coast this year, which has occurred only a handful of times in the same year since the mid-1800s. Only six storms have ever made landfall on the U.S. mainland in a single season. This season isn’t over yet, so topping that record isn’t out of the realm of possibility.“I wouldn’t make too much of that other than bad luck,” Brian McNoldy, a senior research scientist at the University of Miami, told me of the season’s landfall count so far. Helene and most other storms this season have emerged in the western part of the Atlantic basin, which has always been more favorable for storm growth and increases the likelihood of landfall, McNoldy said. Climate change isn’t to blame for where a hurricane touches down, or if it does at all. But Helene’s strength is a different kind of bad luck—a variety that we humans inadvertently engineered. Many of the hurricanes that do reach land these days are more intense because of oceans warmed by climate change. Decades ago, Helene might have become a medium-size storm—still destructive, but not a beast. This hurricane is a sign of America’s relentless hurricane seasons to come.For months now, the waters in the Gulf of Mexico have been abnormally hot, spiking several degrees over the past decade’s average temperatures. “It is simply not within or even close to the range of natural variability to have water temperatures this far above normal in the Gulf, over this wide of an area, to that deep of a depth,” Ryan Truchelut, a meteorologist in Florida who runs the consulting firm WeatherTiger, told me. “When the other ingredients you need to form a hurricane are present, the results are explosive.” In Helene’s case, those other ingredients included the state of hurricane-slowing winds (low) and hurricane-bolstering moisture in the air (plenty), Phil Klotzbach, a meteorologist at Colorado State University, told me. Its massive size was also due to happenstance—a low-pressure system that spun over the Caribbean and Central America a few days before Helene reached the Gulf Coast. Such vortexes are quite common around this time of year, Klotzbach said.These and other factors can make or break a hurricane. If the atmosphere is too dry, or if the wind shear is too intense, storms may never spin their way into Category 1. The problem is that, when atmospheric conditions allow a storm to form, our warming, moistening world is poised to grow them into major threats. “Even 100 years ago, the Gulf would have been plenty warm to support a hurricane of Helene’s strength,” Klotzbach said. But in this century, the chances of this particular outcome are simply higher. Gulf waters may certainly be cooler than average in some years, and perhaps that will be the case next year, which is forecast to be less scorching overall. “But the odds of that go down with continued climate change,” Klotzbach said.Global warming doesn’t dictate whether storms like Beryl and Helene exist, but as Earth continues to heat up, more and more of the disasters that arrive on our shores will bear our fingerprints. “You hope, when you go into these years where the forecasts are really high, that maybe we’ll luck out; maybe we won’t get the big hurricane hits,” Michael Lowry, a hurricane specialist in Miami, told me. So far, the opposite situation is unfolding. And we still have two more months to go.When I spoke with Truchelut at the start of the season, as Beryl strengthened in the Caribbean, he invoked the importance of chance in avoiding a nightmare hurricane, warning that “we might not be so lucky next time.” This week, Truchelut’s personal luck held out: Even as parts of Florida experienced a historic storm surge—the deadliest aspect of hurricanes, and one that is expected to worsen as sea levels rise—Tallahassee, where Truchelut is based, seems to have been spared. The more Atlantic storms make landfall as hurricanes, the greater the chances that each American town or city will face disasters shaped by a combination of natural misfortune and human-made blight. In our warming world, it seems that hurricane country won’t be able to catch a break.

The Nicest Eruption in the World

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theatlantic.com

Earth is an endlessly convulsing world. So much of it is in disequilibrium, riddled by heat, pressure, and chemicals trying to get from their current location to somewhere else. And these forces are powerful enough that they manifest in ways that inadvertently make us feel small: tremendous hurricanes barreling across the sea, thundering earthquakes that can tear apart mountains, tsunamis that wash over and subjugate the land with a preternatural ease. Put us surface dwellers in their path, and we are existentially vulnerable. Natural wonders become disasters.The same is true for plenty of erupting volcanoes, whether they’re exploding with cataclysmic force or oozing incandescent molten rock. But not always. In fact, most volcanic eruptions are harmless—and the latest outburst on the island of Hawaii was one of the loveliest displays of volcanism in quite some time.Earlier this month, a fissure—a thin schism in the crust—opened in a remote, crater-filled area of the Hawaii Volcanoes National Park, on the slopes of the Kīlauea volcano. The outrush of lava began on a Sunday night, but the embers were obscured by heavy rainfall; the only reason scientists at the U.S. Geological Survey’s Hawaiian Volcano Observatory knew anything was happening was because their instruments detected a spike in telltale tremors and muffled thuds, hinting at rapidly moving magma and venting vapors. During a helicopter flight the next day, volcanologists spotted that new fissure’s scar tissue between Makaopuhi Crater and Nāpau Crater, but no freshly extruded lava. Almost as soon as the volcano had started acting up, it took a little break.The pause was one of several diminuendos during this recent, multiday eruption. But each time the volcano started up again, new fissures would score blazing lines across the national park. At one point, a magnificent waterfall-like torrent of lava was seen gushing over the walls of Nāpau Crater. Then, on September 20, as suddenly as they had begun, the volcanic theatrics ended: No new lava was erupting from the site. And a few days later, the eruption was officially declared to be over.Unlike eruptions from a volcano’s clearly identifiable vent, volcanic fissures can pop up anywhere that migrating magma deems fit, which makes them somewhat stealthy and decidedly treacherous to the towns or cities built around them. In this instance, magma found its skylight in a secluded spot. And so it became one of those eruptions that are harmless to us—just the planet letting off a bit of steam. Watching molten rock twist and turn, dance and meander, can inspire a sense of awe. In a world rife with disaster, a little eruption like last week’s fireworks in Hawaii can be almost soul-soothing. Look at that! Earth’s just doing its wondrous, beautiful thing.The better that scientists understand these primeval forces, the more likely they can help everyone else maintain some of this appreciation, even when eruptions become dangerous. In Iceland, for instance, the lava that emerged from the middle of the Reykjanes Peninsula in March 2021, for the first time in eight centuries, began as a dramatic spectacle. Lava quickly fountained from a series of fissures into the sky, before pouring into several uninhabited valleys next to a mountain named Fagradalsfjall. Thousands of revelers sat atop the surrounding hills, watching the eruption as if they were audience members in a volcanic amphitheater. This eruption was followed by two additional outbursts in the same general location before the magmatic forge beneath Reykjanes decided to set up shop elsewhere on the peninsula—this time, near a crucial geothermal power plant and the town of Grindavík.That town has now been besieged by multiple incursions of lava. Lava-deflecting walls—barriers of volcanic rock, which are extended or shifted to combat new fissures—have kept it from being destroyed. But should lava overrun one of these walls, or a fissure unzip the crust in a populated area, people’s lives would be directly imperiled. For Grindavík, this has been a slow-moving disaster of sorts: The repeatedly evacuated site has been essentially a ghost town for almost a year now. Still, to date, not a single person has died as a direct result of the Reykjanes Peninsula’s new volcanism. If the last salvo of eruptions is anything to go by, this flurry of fiery rivers will keep emerging for several decades to come—a testament to both Earth’s power and our capacity to coexist with it.Volcanic eruptions are certainly complicated, but if they happen often enough and are comprehensively monitored, scientists can get rather good at tracking them. And when volcanic activity is a part of people’s daily lives, it might be feared, or marveled at, or respected, but it can also be better understood. Iceland’s volcanologists, for example, have managed to decode the seismic rumblings of the peninsula’s underworld, and track the changing shape of the ground itself, to know precisely when and where the next eruption will begin. They are, in effect, having an ongoing conversation with the volcanic creature under their feet.Kīlauea, too, can be a troublesome volcano. Lava appearing in its summit, or sneaking out of fissures on its flanks, can light up the night sky with a striking vermilion glow, threatening nobody. But in 2018, for example, a Kīlauea eruption destroyed more than 700 homes, displaced about 3,000 people, and caused hundreds of millions of dollars in damages. That molten rock deleted entire neighborhoods. And volcanologists, who have studied Kīlauea for more than a century, are still trying to working out exactly what its magmatic circulatory system looks like. But they can also use the volcano’s seismic symphonies and swelling rooftop to track the subterranean movement of magma. If it’s heading toward a populated area, or somewhere upslope from one, they can sound the alarm. If it’s merely putting on a show, as in the case of this latest conflagration, scientists can chronicle the eruption, take samples of its lava, and get some good practice for a genuine emergency—while us lucky passersby get to gleefully witness it.