humanitarian crisis in some regions.
While El Niño is part of a natural multiyear climate cycle, scientists have noticed that it has been rapidly strengthening like never before, intensified by human-driven climate change, and putting stressed natural systems under extra strain.
In a new update this week, the National Oceanic and Atmospheric Administration's (NOAA) Climate Prediction Center continues to forecast a 75% chance that this El Niño event will be stronger than any previous El Niño since 1950, the earliest year from which NOAA has data to make historical comparisons. Furthermore, this El Niño appears to be going "super" — something that has been expected for weeks.
Weekly NOAA data from the eastern Pacific's El Niño region reveal that sea surface temperatures have reached 3.8 degrees Fahrenheit (2.1 degrees Celsius) above average, hitting the more than 3.6 F (2 C) threshold for a very strong or "super" event. Strictly speaking, NOAA uses three-month averages to categorize strength, as weekly data is more prone to temporary anomalies. But the latest data once again signals where this El Niño is heading, with NOAA forecasting a more than 90% chance of a very strong event emerging in the fall and winter.
How will El Niño impact the U.S.?
During El Niño, warmer waters gather east of the equatorial Pacific, forcing the jet stream south. The patterns associated with El Niño bring exceptionally stormy winter weather and a higher chance of rain and snow across California and Southern states, with Northern states experiencing fewer storms and a milder winter, according to the Climate Prediction Center. El Niño can also increase the risk of high-tide flooding, particularly on the West Coast, according to NOAA.
However, as with climate change in general, El Niño doesn't have the same impacts on all regions. Furthermore, while a more intense El Niño typically increases the certainty of expected impacts, they are not guaranteed.
The last "super" El Niño happened in 2015 and 2016. Associated impacts included a historic hurricane season in the central North Pacific and record drought in the Caribbean, according to Climate.gov. Before that, the last El Niño to go super was in 1997 and 1998. That winter was marked by a variety of extreme weather events, including flooding in the Southeast, an ice storm in the Northeast and tornadoes in Florida, according to a report by the National Climatic Data Center.
Already this year, tropical storms in Hawaii have been attributed to El Niño, with warming in the waters where storms typically form there, CNN reported. Meanwhile, the strengthening of El Niño in the Pacific appears to have left the Atlantic unusually calm. Ars Technica reported that the Atlantic hurricane season passed its traditional peak without a tropical storm or hurricane in what is becoming a historic period of quiet.
What is El Niño?
The NOAA has a diagnostic flowchart for declaring El Niño. (Image credit: NOAA Climate.gov)El Niño affects the whole planet, but it begins with unusually warm waters in the eastern tropical Pacific Ocean. NOAA recognizes El Niño conditions when these waters are at least 0.9 F (0.5 C) warmer than average, while wind, surface pressure and rainfall in the region are also consistent with El Niño conditions. An El Niño is then categorized based on its strength, from weak to very strong. Very strong El Niños (above 3.6 F, or 2 C, warmer than average) are nicknamed "super" El Niños, though this isn't a scientific term.
The European Centre for Medium-Range Weather Forecasts' El Niño models suggest that temperatures are sailing past the 2 C threshold and will exceed 6.3 F (3.5 C) by the end of the year. On Sept. 20, the daily El Niño temperature was 5.5 F (3.06 C), according to The Climate Brink. But while this year's El Niño is certainly supercharged, there's still uncertainty about its impacts.
El Niño forecast
On Sept. 3, the World Meteorological Organization (WMO) released a fresh set of El Niño warnings along with a Global Seasonal Climate Update, which the WMO said offers a more refined picture of expected conditions in the coming months.
"For September-November 2026, WMO multi-model forecasts indicate an increased likelihood of above-normal temperatures across almost all land areas, alongside rainfall patterns showing a pronounced and classic atmospheric response to the strong Pacific El Niño," WMO representatives wrote in a statement.
In other words, much of the world is likely to be hotter than normal, while some areas will experience more rainfall and others will see less. The most severe El Niño impacts will likely be felt outside North America.
Liz Stephens, a professor in climate risks and resilience at the University of Reading in the U.K., recently noted that the Indian monsoon season had seen less rainfall than normal and that satellite data revealed that parts of East Africa, Central America and Southeast Asia are experiencing record-dry conditions. The human impact of such weather can be devastating.
"During the large El Niño event of 1997/1998 the associated flooding in Somalia killed over 2000 people," Stephens said in a statement released Sept. 3. "With a bigger El Niño event on the way, and global temperatures now 0.7°C [1.26 F] higher and capable of holding even more moisture as a result of climate change, scientists are concerned that there is potential for even more severe flooding."
'> US heading for unprecedented El Niño winter: Here's what to expect
The sweet spot was 4.33 billion years ago, although Earth may have become suitable for the RNA World as early as 4.4 billion years ago, given that extreme bombardment by asteroids, comets and other rocky leftovers of planet formation had largely stopped by then, the researchers reported in a study published Tuesday (Sept. 22) in the journal Nature Communications.
The findings give a more precise estimate of the RNA World's onset than previous studies based on geochemical modeling, biomolecular analyses and simulations of early atmospheric chemistry did, study first author Oleg Abramov, a senior scientist at the Arizona-based Planetary Science Institute, told Live Science in an email.
"The timing is consistent with previous estimates of approximately 4.35 billion years ago, but our range of uncertainty is significantly narrower," Abramov explained, adding that "previous ranges included 4.46 to 4.26 billion years ago, and 4.45 to 3.9 billion years ago."
The RNA World is a hypothetical time in Earth's history before the emergence of the Last Universal Common Ancestor (LUCA), the single microbe from which all living things on Earth descend. RNA, or ribonucleic acid, is a single-stranded molecule that is structurally similar to DNA and performs vital functions in living cells. Scientists think the RNA World preceded the emergence of DNA; in that early epoch, RNA would have been the primary replicating substance, carrying genetic information across generations of basic lifeforms by copying itself independently.
RNA evolved into its more chemically stable cousin, DNA, sometime before the emergence of LUCA. Scientists think the RNA World first developed into an RNA-and-protein world, and that DNA then appeared in two distinct stages nicknamed the U-DNA and T-DNA worlds.
While researchers have suggested alternative and hybrid scenarios for the emergence of life on Earth, the RNA World is a leading hypothesis, Abramov said. To determine when it might have existed, he and his colleagues built a computer model of Earth's interior that simulated how giant impacts on the planet's surface between 4.5 billion and 3.5 billion years ago affected conditions in the crust and Earth's overall compatibility with life.
"We constructed an impact bombardment model constrained by observables such as the lunar cratering record," Abramov said. "We examined both detrimental effects of impacts, such as temperature-induced degradation of key biomolecules, and effects conducive to life, such as generation of hydrothermal systems."
The model showed that space rocks measuring hundreds of miles across — an order of magnitude larger than the asteroid that killed the dinosaurs, but far smaller than the impactor that created the moon — went on slamming into Earth and sterilizing its surface until 4.4 billion years ago. Life could not have survived such intense bombardment, which probably triggered widespread melting of the crust, ocean vaporization, extreme temperature gradients in the crust and continuous showers of burning material and rock-vapor rain at the surface, Abramov said.
However, the conditions stabilized after 4.4 billion years ago. And as a result, hydrothermal vent clusters appeared within the near-surface crust that concentrated the ingredients for RNA, including nucleotides, short amino-acid chains called peptides and fat-like compounds known as lipids, Abramov said.
"These criteria point to the Earth becoming suitable for an RNA World between 4.4 and 4.3 billion years ago, with optimal conditions at approximately 4.33 billion years ago," he said.
The results suggest there was a gap of roughly 130 million years between the heyday of the RNA World and the emergence of LUCA, which scientists think lived about 4.2 billion years ago. However, there are still large uncertainties around both events, so the interval could be as big as 240 million years, Abramov noted.
"The duration of the RNA World is highly uncertain, and our study did not explicitly constrain it," he said.
'> Scientists identify 'sweet spot' for early stage of life on Earth that preceded LUCA, the ancestor of all living things How the trenches formed wasn't clear. There is no evidence that they were created by the wind, Lipar noted. And it's.unlikely that they were carved out by flowing water, because unlike typical valleys, the trenches don't have connected streams or other signs that water once flowed through them, Lipar explained.
An aerial view of one of the trenches on the Nullarbor Plain. (Image credit: Matej Lipar)To investigate the mysterious trenches' origin, Lipar and his colleagues ran exaggerated digital models of the terrain to make the trenches easier to see and identify where the team needed to focus. Then, they used an imaging technique called electrical resistivity tomography — which measures how electrical currents flow through the ground — to distinguish rock from sediment.
The results revealed that the trenches were dips at the top of what seemed almost like canyons stretching down more than 130 feet (40 m) below the surface. They were filled with sediment, with sand dominating the upper layers and higher proportions of fine particles of silt and clay below that.
When the team looked at a database of known caves, they found that some big, deep caves were lined up along the trenches. The accessible ones can often be reached via sinkholes — also known as dolines — and contain massive passages that can stretch for hundreds of metres. Their similar orientation to the trenches suggests the caves were formed in the porous, karst limestone area by groundwater flowing toward the coast during the Oligocene (33.9 million to 23 million years ago) and Early Miocene (23 million to 16 million years ago), Lipar said.
"Over time, the cave roofs progressively collapsed, causing sagging of overlying material, eventually creating these shallow depressions at the surface," Lipar said. The work was published Sept. 17 in the journal Communications Earth and Environment.
"What this also tells you is that when the trenches end, we might still have a cave that hasn't collapsed yet," Lipar said, and that might help us locate big caves that have never been seen by human eyes before.
The team confirmed their ideas by entering Clay Dam Cave, which is accessible by a sinkhole within a trench, finding that its sagging strata and sandy sediment infill matched what they'd detected in the other trenches.
The researchers explored one of the caves beneath the plain. (Image credit: Matej Lipar)"The authors skillfully show that the linear depressions along the margin of the Nullarbor Plain are probably the surface expression of the progressive collapse of ancient underground cavities," Andrea Zerboni, an Earth scientist at the University of Milan who wasn't involved in the study, told Live Science.
The fact that some trenches are fragmented implies this process is ongoing, and there might be more collapses in the future, Lipar said.
Maximilian Dröllner, a geoscientist at the University of Göttingen in Germany who wasn't involved in the study, told Live Science that the work "could help identify similar caves elsewhere and may be particularly valuable for the study of caves and potentially habitable environments on other planetary bodies."
Similar features have been seen in other deserts, including parts of the Arabian Peninsula, where networks of collapsed caves can be recognized at the surface as elongated depressions, Zerboni noted.
And beyond Earth the implications could be particularly intriguing. "Elongated depressions on Mars have often been interpreted as collapsed lava tubes," Zerboni said. "However, this study shows that superficially similar structures may also result from the collapse of underground systems formed by karst-like rock-alteration processes."
This insight might help scientists pinpoint good places to look for signs of extraterrestrial life. "Subsurface cavities are among the most promising environments in which past life — or traces of it — might have been protected from radiation, extreme temperatures and surface weathering," Zerboni said.
'> Giant caves beneath sinkhole reveal origin of mystery trenches that score Australia's Nullarbor Plain A researcher cleans part of an ancient mosaic. The school was quite opulent, as it was funded by Philip II for educating Alexander and other Macedonian nobles. (Image credit: Copyright Hellenic Ministry of Culture)According to Plutarch, Philip II, had this school built "for the education of his son Alexander and the children of the noble Macedonians," Kottaridi told Live Science in an email. Schools in the ancient Greek world, called "gymnasia," taught students a variety of subjects and also trained them physically.
The discovery of the school was a bit indirect, Kottaridi said. "A few years ago, I identified the ancient remains next to the ancient theater of Mieza," she said, and her team began excavating the building complex in 2024. But some excavation of the complex had been done more than 20 years earlier, she explained, when a monument dedicated to the nymphs was found nearby.
Scholars supportive
Live Science reached out to scholars not involved with the excavation, and they were supportive of the idea that Alexander the Great studied at this school.
"I agree that all the evidence suggests this is the school Philip provided for Aristotle to tutor the young Alexander and his fellow students," Jeanne Reames, the director of the Ancient Mediterranean Studies program at the University of Nebraska at Omaha, told Live Science in an email. Reames hopes that more information will be released and that the discovery will "shed more light on elite education in Macedonia in the second half of the 4th century" B.C.
Another aerial image showing more of the school where Aristotle taught Alexander. (Image credit: Copyright Hellenic Ministry of Culture)Graham Wrightson, a history professor at South Dakota State University, told Live Science in an email that "Alexander studied there under Aristotle so it is exciting to excavate the very school rooms where his teacher shaped his formative years." The discovery of "four stylus writing implements allows us to dream that one belonged to Alexander," Wrightston said, even if none of them truly did. "Still, it allows us to put ourselves in the shoes of the young Alexander and understand more how he became the famous king."
It's unsurprising that the school was so opulent given Philip II's great wealth, Elizabeth Baynham, a senior lecturer at the University of Newcastle in Australia, told Live Science in an email.
Political assassinations weren't unheard of in those days — for instance, during the Roman Empire, which arose after Alexander's death, about 20% of Rome's 82 emperors were assassinated while in office. So safety may have played a role in the school's location. The distance from the school to Macedonia's ancient capital at Pella — about 27 miles (43 kilometers) away — was "far enough away to potentially give Alexander a chance for escape if his father was assassinated," Baynham said.
The education that Alexander and his school mates received from Aristotle would have been excellent, Baynham said. "Alexander — who by all accounts was highly intelligent — was taught by one of the finest minds of the ancient world in terms of range and insight. Aristotle would have only been in his early 40s."
But more archaeological information on the site is needed, historian Miltiades Hatzopoulos told Live Science in an email. While this is likely the school where Alexander was taught, "the excavator has given interviews, but has not yet published a paper with the relevant testimonies," Hatzopoulos said.
See how much you know about Alexander the Great with our Alexander the Great quiz!
'> Nearly 2,400-year-old school where Aristotle taught Alexander the Great discovered in Greece
more than 3 million photos of the lunar surface. This week, scientists studying a few hundred of those photos announced what they're calling a
"once-in-a-century" discovery: the biggest, freshest impact crater ever seen in the solar system. It's the result of a building-size meteorite that slammed into the moon just two years ago.
The new lunar pockmark, named McGetchin crater after the late geologist and lunar scientist Tom McGetchin, is about 728 feet (222 meters) wide, on average, and 141 feet (43 m) deep — imagine a hole as long as two American football fields and deep enough to fit a 14-story building inside.
"We know generally that there's more small things in space than there are large things, so that means we tend to get a lot of small craters on the moon and very few large craters," Julie Stopar, a senior scientist at the Lunar and Planetary Institute and deputy principal investigator on the LRO's camera team, told Live Science. "So something the size of this crater, we only expect to encounter that once every 130 years, approximately."
McGetchin is nowhere near the moon's largest crater; that honor goes to the South Pole-Aitken basin, a gargantuan gouge about 10,000 times wider than the newly discovered crater. But McGetchin is the largest new crater. Appearing seemingly out of nowhere in images from spring 2024, it's the biggest one scientists have seen in the 17 years that LRO has been active. And now that it's known to the world, some intrepid skywatchers think they've spotted the crater's bright, white debris ring from Earth.
The team described their findings in two papers published Sept. 16 in the journal Science Advances. Live Science spoke with Stopar to find out what this fresh crater can teach us about lunar geology, impact rates and potential risks to the future human visitors to the moon.
Brandon Specktor: The moon is riddled with craters. What's so interesting about this new one?
Julie Stopar: On one hand, it's a nice crater because it's so fresh and new. It hasn't been weathered. On Earth, we see the remnants of impact craters, but a lot of the original details are lost through weathering and degradation and time. But the moon preserves all of that much better.
This crater, in particular, is so fresh and young — it's only about 2.5 years old. It's in really, really good condition. We can study it to understand how impact cratering occurs and all the processes that go along with it.
The other cool thing is that it impacted on the boundary between two different types of deposits on the moon. There's the volcanic mare deposits [dark patches visible from Earth] and there's the highlands, which are ancient crustal material. The highlands are brighter and tend to be hillier, more mountainous, whereas the mare are flat plains, and they're very dark. This impact seems to have occurred right on the boundary between those two areas, so that's reflected in the materials that are excavated by that crater.
BS: The meteorite that made this crater was the size of a three-to-six-story building, according to your team's estimates. Could we have seen this impact from Earth?
JS: Yes. This is a relatively large impact, and from Earth, we have observed flashes associated with smaller impacts. So I think it's possible, under good conditions, that this may have made a flash. We don't know if anyone was watching, though — so if somebody out there has videos that they can dig through, they could go back and look for it.
A global view of the moon made from hundreds of images taken by the Wide-Angle Camera aboard NASA's Lunar Reconnaissance Orbiter. The black arrow shows the location of McGetchin crater. (Image credit: NASA Lunar Reconnaissance Orbiter)BS: This impact happened in April or May 2024. One of your colleagues discovered the crater in LRO data in October 2025. Why did it take so long?
JS: LRO orbits the moon about 12 times each day. While we're going around, we can only image a really small portion of the moon on each pass. So you can imagine it takes many, many orbits to go around the moon and to reimage each part of the surface. When we don't have an impact flash to help us decide where to look for these craters, it's basically a random search.
Over time, we eventually will get repeat imaging [of the same area], but it takes years to get that. On top of that, the processing that it takes to make the before and after images
takes a lot of work; basically, you're looking through all the images that have been taken of the moon under the right conditions, and it just takes a lot of time and effort to process that.
BS: Your colleague, Robert Wagner, says he "stopped and dropped everything" when he discovered the crater in LRO's data. What was your reaction when he first showed it to you?
JS: I was surprised that it was so large! But I've seen a lot of similar craters on the moon, so my actual first thought was, "Oh my gosh; this crater might actually help me constrain how old all of these other craters are!"
BS: So because you know this crater is so fresh, it's helping you date other craters you've seen too?
JS: Yes, I've been looking at a bunch of craters, which I think look morphologically [their shape] and albedo-wise [how much light they reflect into space] very fresh. They have the bright ejecta [the material that gets blasted out from the meteor impact]; they have crisp rims. But I don't know how old they are, because they were there before the LRO. I think they're young, but I don't have any proof of age. So that was my first thought: "Oh my gosh; this makes me feel so much better if all these other craters I'm studying are still in really good condition like this one is."
McGetchin crater, circled in white, as seen in a 2025 LRO image (left) compared to an image of the same part of the moon taken in 2011 (right). Scientists think the crater formed between April and May of 2024. (Image credit: NASA Lunar Reconnaissance Orbiter)BS: What, specifically, do you hope to learn about the moon from this crater?
JS: There's hope that we can use this to help understand the current impact cratering rate. How much and how often do different sizes of debris in the solar system impact the moon?
And that's important, because people want to go to the surface for exploration, send landers, start building moon bases and so forth, and there's some concern that impactors will be a hazard. So it would be helpful to have a better idea of whether that's a really frequent concern or only a once-in-a-while concern. We can also study things like how the impact angle, the target materials, and the velocity and type of impactor play a role in forming craters.
This crater will help us better interpret all of the others as well. I think this would be a really good crater to go get samples from, because we know when it formed and we have a lot of questions we can answer with that.
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BS: How do you see human-made impacts fitting into this? In recent years, several spacecraft have crashed into the moon. Do you see any risks there or more opportunities to study craters?
JS: At this point, it's not too much of a concern to myself about human-made objects destroying natural habitats on the moon. Other spacecraft impacts, like the boosters from the Apollo program, made craters a long time ago. But I think, as there are more people and countries and even companies going to the moon, they'll have to get coordinated so as to not interfere with each other's activities — because that would be a problem. It's just a reminder like, "Hey, guys; you need to talk to each other and get coordinated and make sure you're keeping track of these impacts and your debris, and you're working together."
Otherwise, those craters are interesting because we know the impactor's mass and shape beforehand. It gives us a new insight into how craters form when you have irregularly shaped masses, like hollow cylinders and things like that. They'll also tell us about the moon's surface as well, because it's a different type of impact and it's got a different kind of energy to it and a different shape. So we do learn a lot about the cratering process in general from those.
This interview has been condensed and edited lightly for clarity.
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'> 'Once every 130 years': A huge new crater on the moon could be a giant leap for lunar science, researcher says