Each year, about this time, the Karolinska Institute and Royal Swedish Academy of Sciences — both in Stockholm, Sweden — announce three world-changing achievements. People who pioneered the work in these fields will receive the most coveted science awards on Earth: the Nobels.

The first of the 2026 prizes was awarded for finding a light switch for the brain. The second goes for developing a literally super-cool way to study elusive particles bombarding Earth from outside our solar system. And the last prize highlights the importance of being able to preferentially make certain “handed” molecules.

All three achievements opened up major new windows on — and opportunities in — biology, physics and chemistry.

Shining a light on brain function

Let’s start with the human brain. It hosts nearly 90 billion neurons. They talk amongst each other through some 100 trillion connections. This brain chatter allows our minds to learn, adapt and interact with the world around us.

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The 2026 Nobel Prize in physiology or medicine went to Karl Deisseroth, Peter Hegemann and Georg Nagel for developing ways to control nerve cells with light. The technique, called optogenetics, opened new ways to study the brain by turning individual neurons on and off. #nobel #optogenetics #sciencenews Nikk Ogasa Getty Images/Alexander Pytskiy/JONATHAN NACKSTRAND/JOHN SAEKI,LAURENCE CHU/VALENTINA BRESCHI,JONATHAN WALTER,SYLVIE HUSSON,OLIVIER THIBAULT

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To find out how, brain scientists needed a special tool. They long “dreamed” of something that might let them “turn specific neurons on or off with great precision,” notes Abdel El Manira. He spoke on Oct. 5, describing the prize for this tool.

Called optogenetics, that tool uses light to switch on specific neurons. Afterward, researchers can watch how a host’s behavior may have changed.

The path to the prize started in an unlikely place: the “eye spot” of a single-celled green alga.

In the early 2000s, biophysicists in Germany discovered a unique protein in that alga’s “eye” spot. The two researchers were Peter Hegemann (who now works at Humboldt University in Berlin, Germany) and Georg Nagel (at the Julius-Maximilians-Universität Würzburg in Germany). The protein that caught their interest had a long name: channelrhodopsin (CHAA-nel-roh-DOP-sin).

When light hits it, the protein produces an electrical impulse. This triggered the alga to move. Later research would show light caused that protein to open like a pore. That let positively charged ions flow into the cell. They are what caused the electrical impulse.

Hegemann and Nagel “had just discovered the switch neuroscientists had long dreamed of,” says El Manira.

Building on the that work, Karl Deisseroth tried using that protein to see if it could turn on brain cells. A neuroscientist, he works at Stanford University in California.

He was part of a team that inserted the gene to make channelrhodopsin into rat nerve cells. These were growing in dishes in the lab. Shining light on the cells triggered an immediate reaction.

This team also put the gene into nerve cells within the brains of living mice. The researchers inserted optical fibers at the same spots, right through the rodents’ skulls. By shining blue light through the fibers, the researchers could now control the movements of the rodents’ whiskers.

Researchers later went on to test the links between other brain circuits and behaviors.

In short order, optogenetics “transformed neuroscience,” El Manira says. It offered a window on the workings of healthy brains, he says. It helped show how brain circuits can be disrupted, too, he adds. Those findings, he notes, could help researchers treat conditions such as blindness, depression and dementia.

In fact, we didn’t have to wait long for news in one of those areas. Just two days after this Nobel was announced, other researchers described a light therapy for retinitis pigmentosa (Reh-tih-NY-tis Pig-men-TOW-sah). This blinding disease slowly kills off light-sensing cells in the eye’s retina. Optogenetics, the new report showed, helped improve light sensitivity in seven of 10 treated people.

For their pivotal role in optogenetics, all three men are sharing the 2026 Nobel in physiology or medicine.

Hunting for ‘ghost’ particles

At the South Pole, scientists have threaded one cubic kilometer (1.3 billion cubic yards) of the ice sheet with thousands of beadlike sensors. Together, the sensors make up the IceCube Neutrino Observatory. The immense instrument lets researchers detect some of the most elusive — shyest, some say — subatomic particles in the cosmos: neutrinos.

Neutrinos have no electric charge. They can pass through objects without interacting. In fact, billions of these ghostly particles pass through each of us every second.

Fusion reactions in our sun form most of them. But some had been thought to come from much farther away — in high-energy particle collisions too far off to observe.

Detecting such neutrinos from well beyond our solar system had long been a goal of scientists. Because neutrinos are not deflected by magnetic fields and rarely interact with matter, detecting their path could point back to their distant source. Scientists hoped to one day figure out where and how the universe accelerated these super-small particles to super-high energies.

In the 1980s, physicist Francis Halzen of the University of Wisconsin–Madison had an insight: The South Pole should be an ideal place to look for the flashes of light created by the rare events when neutrinos collide with atomic nuclei. Ice deep within the Antarctic ice sheet could make a large, dark, transparent stage for such a neutrino light show.

This vision of Halzen’s was realized in 2011. That’s when IceCube’s construction was complete.

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Francis Halzen has won the 2026 Nobel Prize in physics for his vision and scientific leadership of the IceCube Neutrino Observatory. IceCube gave us an entirely new way to see the universe. #nobelprize #physics #sciencenews Nikk Ogasa Getty Images/MARCO BERTORELLO/NSF/Martin Wolf & Sven Lidstrom, IceCube

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In part, Halzen got this year’s physics Nobel “for his decisive contributions to [IceCube].” notes physicist Mark Pearce. But Halzen also won for “the discovery of high-energy neutrinos of astrophysical origin,” he adds. Pearce, who chairs the Nobel committee for physics, spoke during the Oct. 6 award announcement by the Royal Swedish Academy of Sciences.

IceCube had been a gamble. “Nobody knew whether a kilometer-field detector was actually large enough to discover neutrinos beyond our atmosphere from the universe,” Halzen said in a phone call during the announcement ceremony.

In fact, he noted, “It only took us two years to detect them.”

And the discoveries didn’t end there. Using IceCube data, researchers reported in 2018 that they had traced a neutrino back to the brilliant core of a distant galaxy, called a blazar. And in 2023, researchers used a decade of IceCube data to produce the first map of the Milky Way made with something other than light.

Plans for a global network of neutrino detectors are now in motion.

This year isn’t the first time a Nobel has gone for work on neutrinos. Two physicists received the prize in 2015 for demonstrating that neutrinos have mass.

On the one hand …

In nature, the building blocks of life exhibit a striking pattern. Many can exist in two mirror-image structures, much like your right and left hand. Such molecules are said to be chiral (KY-rul). However, in nature, such chiral molecules overwhelmingly occur in just one form. Amino acids, for instance, are nearly always left-handed.

Known as homochirality, this dominance of one type of handedness had long puzzled scientists.

When chemists first attempted to make chiral molecules in the lab, they ended up with roughly 50-50 mixes of right- and left-handed molecules. Why?

“It is this puzzle that this year’s laureates have solved,” said Heiner Linke. He spoke during the Oct. 7 announcement of the chemistry prize by the Royal Swedish Academy of Sciences.

Two scientists will split this Nobel prize. Henri Kagan works at the Université Paris-Saclay in France. Kenso Soai works at Tokyo University of Science in Japan.

They will share it for discovering a path to creating chiral molecules in such a way that they make one of the possible mirror-image forms. “This is the first time this had happened since the processes that led to the chirality of life billions of years ago,” says Linke. A physicist at Lund University in Sweden, he chairs the Nobel Committee for Chemistry.

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Henri Kagan and Kenso Soai won the 2026 Nobel Prize in chemistry for their work on controlling the production of mirror-image molecules. Their discoveries have helped pharmaceutical companies develop safer drugs. #nobel #chemistry #sciencenews Nikk Ogasa Getty Images/Evening Standard/Paul Fievez/Keystone/JONATHAN NACKSTRAND

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The award winners’ research has greatly aided development of medicines. A lot of active drug molecules are chiral. But while one form may have a medicinal effect, its mirror-image form might have no effect — or worse, be harmful.

Consider thalidomide (Thuh-LID-oh-myde). Thousands of babies were born in the 1950s with severe birth defects. Their mothers had been prescribed thalidomide while they were pregnant to treat anxiety and nausea. Science would later show that the left-handed form of the drug was toxic. (Even taking the “safe,” right-handed form wouldn’t solve the problem. In the body, it could morph into the left-handed form.)  

In 1986, Kagan’s team was the first to report chemical reactions that would lead to production techniques that helped solve the problem. These could make a far larger than normal share of left- or right-handed forms.

Several years later, Soai and his colleagues reported that they had figured out how to make a chiral catalyst that could, in turn, be used to form itself. That allowed his team to perform reactions that resulted in products made almost entirely of one “handed” form of a chiral molecule.

“This is not the final answer,” Soai said of this work. He had called in from Japan to the Nobel announcement ceremony. Speaking to future generations, Soai said, “the study of chirality should be more and more developed.”

The new Nobel scientists will each get a medal. The winners in each category will also split 12 million Swedish kroner (roughly $1.2 million).

Since June, scientists have been warning that Earth might experience an El Niño unlike any other. It now appears they were right. The periodic climate beast that emerged this year is stronger than any ever seen. And the really worrisome news: It likely hasn’t even reached its peak.

El Niños develop in the central and eastern equatorial Pacific Ocean. Over a short period, they release extraordinary amounts of ocean heat into the air. And by September 21, the daily sea-surface temperature where El Niños form was already 3.08 degrees Celsius (5.54 degrees Fahrenheit) warmer than the average from 1991 to 2020.

El Niños can fuel droughts, floods, heat waves and severe storms. The Oceanic Niño Index is a traditional measurement of their strength. Using daily sea-surface temperatures to calculate strength shows that the 2026 event is already more intense than any in recorded history.

“It has been a remarkable event,” says Nathaniel Johnson. What’s more, the climate scientist notes, this El Niño will probably strengthen even more. He expects it to peak “within the next few months.” Johnson works at the Geophysical Fluid Dynamics Laboratory in Princeton, N.J. It’s part of the National Oceanic and Atmospheric Administration (NOAA).

Ocean heat released by this El Niño could spike global land temperatures about 1.2 degrees C (2.16 degrees F) in the coming months. That may not sound like much. But by next February, it could lead to more than 450,000 additional heat-related deaths. That’s the finding of a new report out of the University of Chicago’s Climate Impact Lab.

NOAA has not yet formally called this El Niño a record-breaker. Why? It’s using a new measurement method: the Relative Oceanic Niño index. That should better capture how an El Niño’s heat will alter weather across the globe. And by this index, the El Niño in 1997 and 1998 topped the new one’s current strength.

But that record, too, is on track to be broken soon, based on a Sept. 10 forecast by NOAA’s Climate Prediction Center.

To understand what’s driving this historic event and its potential impacts, Science News spoke with two experts. One is Johnson, part of that U.S. team that produces El Niño forecasts. The other, Nathan Lenssen, is a climate scientist at the National Center of Atmospheric Research. It’s in Boulder, Colo. Their answers have been edited for length and clarity.

How much of this El Niño’s strength has been fueled by human-caused climate change?

Johnson: It’s really an unanswered question. If we look at the historical record, we have been seeing more rapid swings between El Niño and La Niña. [La Niña is the other — and opposite — extreme phase of a seesawing pair of climate patterns: Together they’re known as ENSO, or the El Niño Southern Oscillation.] There’s some evidence from computer models that increasing greenhouse-gas emissions lead to more of those extreme [ENSO] swings. But there’s no science consensus yet on how climate change is impacting El Niño. Especially an extreme one, like this.

Lenssen: There’s debate on how much we can directly attribute to climate change. But due to Earth’s warming, there is more energy in the oceans now. And El Niños release some of that ocean heat into the atmosphere.

What are the most predictable and unpredictable impacts of this El Niño?

Johnson: We see a lot of the most predictable impacts in the tropics. That’s where an El Niño develops. We’ve already seen a suppressed Atlantic hurricane season and enhanced Pacific hurricane season. We’ve also seen droughts in Central America. We tend to see droughts over northern South America and the Amazon. Meanwhile, the Indian monsoon can weaken.

By late fall, we typically see more impacts a bit farther from the equator. For instance, we tend to see more rain over the southern United States, but it’s typically drier than normal over the Pacific Northwest. And it’ll be warmer than average over the northern United States and Canada.

Lenssen: While this El Niño is quite powerful, that doesn’t necessarily mean we’re more confident about its impacts. A global warming of the oceans has made some historical changes seen at mid-latitudes less likely.

So there’s a kind of twist there. The El Niño in 2023 and 2024, for instance, didn’t lead to as much wet weather in California as expected. And some research has shown that was due to other warming ocean patterns.

How long could this El Niño last?

Johnson: El Niños typically last a year. So we’ll probably see this one weaken after winter and be over by spring or early summer. But when we have a big El Niño like this, we’re more likely to see a shift in the following year to La Niña [which also has global impacts on weather]. So that’s something we’ll be keeping our eye on.

Lenssen: It’s possible that this event could be followed by a double La Niña. Those occur back-to-back, separated by a brief period of neutral conditions. That happened in 2016 and 2017, after the strong El Niño of 2014 and 2015.

Aside from strength, what sets this event apart from past ones?

Johnson: We’ve seen such a dramatic change in the equatorial Pacific Ocean. The move has been very rapid, from a La Niña last winter to a very strong El Niño — all in less than a year. That might be the fastest transition that we’ve seen.

Is there any sort of silver lining here?

Lenssen: Though more work is needed to understand this, some research suggests future El Niños may actually become more predictable as the world continues to warm. That might give us months of additional lead time to prepare for their impacts. And that would be great.

A warming climate has been helping drive a global rise in sea levels. A new analysis now finds that hundreds of major studies missed just how much sea levels have risen. Past estimates were too low, the new study shows. On average, true sea levels are 20 to 30 centimeters (8 to 12 inches) higher than what past studies reported.

This means that the toll of future sea level rise is even greater than expected.

Katharina Seeger and Philip Minderhoud did the research. They work at Wageningen University in the Netherlands. These physical geographers evaluated data from 385 global and regional studies. All had been published between 2009 and 2025.

Some 99 percent of the studies had incorrectly estimated ocean height, they found. And 45 of the studies were used a few years ago in a major report. It was issued by a global panel of climate experts convened by the United Nations.

Knowing the rate of ocean rise is crucial for coastal planners around the world. It helps them predict when sea water will start to flood — and permanently cover — large swaths of land. The errors in past studies, the researchers say, mean that coastal land may disappear faster than expected. In some places, it could vanish as much as a century sooner than thought.

The team shared its findings in the April 16 Nature.

A one-meter (39-inch) rise in sea level — which could happen within a century — could submerge an area more than 30 percent bigger than scientists thought. That would take away land from 77 to 132 million people. That’s 48 to 68 percent more people than previous estimates.

Sea level rise is slow. But it’s also dangerous if you ignore it, says Anders Levermann. “That’s basically what we’ve done, unknowingly,” he says. “These estimates now tell us that we are much further in the future than we thought we were.” A climate scientist, Levermann works at the Potsdam Institute for Climate Research in Germany.

One problem: geoids

Some of the analyzed studies had focused on sea level rise. Others had focused on storm surges, tsunamis or other coastal hazards. And a common mistake emerged in nine out of every 10 of the studies, the researchers say.

It had to do with the type of data used.

Researchers usually gauge coastal flood hazards by comparing a site’s land elevation to sea levels. Ideally, those sea levels come from actual measurements. Those can come from satellites. Or they could be from tidal gauges, ocean buoys or other tools.

But few of the studies Seeger and Minderhoud reviewed had included such direct sea-level measurements. Instead, the studies had relied on wonky, digital shapes called geoids (GEE-oids).

Geoids are imaginary shapes. They’re meant to approximate Earth’s sea level. They don’t show big ice sheets or giant mountain peaks. Instead, they show Earth as a sort of irregular ball of water with an undulating surface.

But there are two key problems to using geoids to gauge sea level, Seeger and Minderhoud say. First, geoids can be off by several meters. Gravity data are key for making geoids. So geoids are less accurate where gravity data are poor. Those areas include the Global South.

Second, geoids do not account for many other things that can affect sea level. These include ocean circulation and currents. Winds, tides and water temperatures also play roles.

It’s possible to correct for these geoid problems, Minderhoud said at a March 3 news briefing. But the new research shows that few scientists studying coastal hazards make those fixes.

Geoid assumptions led to errors in 90 percent of the reviewed studies. Another 9 percent did not align measurements of sea level and land elevation properly. Fewer than one percent of the studies properly aligned such data, Seeger said.

Average errors varied by region

To see how far off sea-level numbers had been in most studies, Seeger and Minderhoud turned to satellite data. These data measured sea-surface heights globally. Compared to these, geoid-based studies had underestimated coastal sea level by an average of 24 to 27 centimeters (about 10 inches).

Errors were more than three times that size for some places. Among these were parts of Southeast Asia and the Indo-Pacific.

For a few places, estimates of sea levels had actually been too high. These regions included the northern Mediterranean and Antarctica.  That was also true for some islands in the Atlantic and Pacific.

Study estimates were closest for eastern North America and northern and western Europe. Overall, though, most measured sea levels were higher than what past studies had published.

This means the advance of the oceans “is even worse than what’s been reported,” says Patrick Barnard. A coastal geologist, he works at the University of California, Santa Cruz. The new work, he says, is important for planners. It suggests they should be cautious when using findings from big-picture studies to guide local efforts to adapt to sea level rise.

To help future studies, Seeger and Minderhoud have publicly shared coastal sea-level data. These include the most recent actual measurements.