The Brief

Ships plying the frigid waters near the Antarctic Peninsula, south of South America, will need to keep an eye on their radar for a floating island of ice: "The largest iceberg in the world, A-23a, is on the move into open ocean!" as the British Antarctic Survey recently announced.

"It's a trillion tons of ice. So it's hard to comprehend just how big a patch of ice this is," Ted Scambos, a senior research scientist at the University of Colorado Boulder, told NPR.

Iceberg A23a measures 40 by 32 nautical miles, according to the U.S. National Ice Center. For comparison, Hawaii's island of Oahu is 44 miles long and 30 miles across. And New York City's Manhattan Island is about 13.4 miles long and spans around 2.3 miles at its widest point.

When A23a was still part of an ice shelf, it held a Soviet research station — and it whisked that base off to sea when it floated away in the 1980s (more on that below). The iceberg then became grounded on the seafloor. But in recent years, it has been on the move again, after shaking loose.

Here's a quick recap of the iceberg, its history and its potential future:

It's the world's biggest iceberg

A23a hasn't always held the title. In 2021, for instance, it was supplanted by iceberg A-76, which broke from the Ronne Ice Shelf, also in the Weddell Sea. But that giant soon fractured into smaller icebergs, putting A23a back into the top spot.

"It's truly a gargantuan piece of ice," Scambos said, noting that the iceberg is likely 1,000 to 1,200 feet thick.

Its roots stretch to the austral winter of 1986, when the Filchner Ice Shelf's leading edge broke off to calve three huge icebergs: A22, A23 and A24. In late 1991, A23a became a separate iceberg.

A23a was grounded for decades

Recent satellite images have shown the migration of the mammoth iceberg known as A23a from its origins in the Weddell Sea to its current position on the edge of the open ocean.

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Worldview/NASA Earth Observing System/Screenshot by NPR

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If icebergs were humans, A23a would be a millennial. And like members of that generation who have sometimes been forced to stay home by harsh economic conditions, the iceberg has spent most of its independent existence grounded, stuck to a sandbank in shallow waters.

Little by little, the iceberg kept scouring a path over the seafloor and toward deeper water, nudged by currents, the wind and other factors. A breakthrough came in 2020, when the main bulk of A23a freed itself and started to pivot clockwise on its southeast corner. Before long, it was moving in earnest.

It took ice station Druzhnaya 1 out to sea

A map shows the locations of research stations in Antarctica, focusing on the coast of the Weddell Sea.

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U.S. Geological Survey

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Over the decades, the Filchner Ice Shelf has hosted several countries' research and mapping stations. For about 10 years, that included a Soviet station called Druzhnaya 1.

"When the A23 iceberg calved and floated off" in 1986, "Druzhnaya 1 was still on it," according to the U.S. Geological Survey.

In February 1987, a Soviet ship, the Kapitan Kondratyev, tracked the iceberg down and deployed a landing party aboard a helicopter "to salvage the most valuable equipment from the station," as researchers noted in a recent academic paper.

Life can get weird on an iceberg

If you were to set foot on A23a, Scambos said, you likely wouldn't realize it's an iceberg, floating loose at sea. Its scale would simply fill the horizon; any movement would be imperceptible. He should know. He has camped on icebergs before.

He recalls one odd thing: the disorientation.

"The ice that the base was built on would start to rotate, and that would make the sun do funny things in the sky," Scambos said. "It wouldn't be where it's supposed to be in the morning or in the evening or at night — even though it's 24 hours of daylight."

Over the years, he has heard from people who want to visit an iceberg. And Scambos says that while some of their goals were outlandish (as in, people hoping to declare unilateral sovereignty over an ice kingdom), a gigantic iceberg like A23a is pretty stable — with a big caveat.

"It's not impossible to land on it," Scambos said. "I mean, the upper surface is going to be smooth and snowy and relatively safe, at least for now."

But as the iceberg drifts north and finds warmer conditions, melting and flooding will begin.

"Eventually it will start to crack apart fairly rapidly towards the end," he said. "You wouldn't want to be on it at the end, because the whole thing would be breaking off in pieces and falling into the ocean."

Huge icebergs have drifted far distances

Most icebergs emerging from the Weddell Sea tend to drift slightly eastward toward South Georgia, some 1,000 miles east of the tip of South America.

If that happens to A23a, it could run aground again near South Georgia. But other icebergs, like its sibling A24, have moved more directly north, toward the Falkland Islands.

"Usually they're in the process of breaking up at that point," Scambos said, "although this one is likely to survive longer than most because it came from a colder part of Antarctica" and is thick, along with having a heavy buildup of snowfall.

If A23a doesn't get hung up in shallow and warmer waters, he added, "it could wind up drifting south of Africa into the Indian Ocean. They've even drifted all the way into the Pacific and wound up coming up on Chile, almost circumnavigating the globe. Some of the largest icebergs have done that in the past."

You can learn a lot from an iceberg

Massive icebergs like A23a scrape and scour the seafloor in shallow waters.

"There's a lot of life that lives in the bottom of the ocean that is just completely crushed, wrecked, when one of these things passes over," Scambos said. "That's it for the ecosystem that lives in that part of the ocean."

But the icebergs also give scientists an idea of the changes wrought when massive plates of ice, formed in the coldest parts of the world, suddenly find themselves in warmer conditions.

"The main scientific source of interest for the iceberg is sampling ocean surface waters behind, near, and just ahead of it," Em Newton of the British Antarctic Survey said of A23a, in a message to NPR. Researchers, she added, want "to understand the effects of temperature, changes to salinity, released nutrients, etc., along its path."

This part of the Southern Ocean is normally very poor in nutrients. An iceberg like A23a, Scambos says, can help change that by shedding nutrients it accumulated from Antarctica and stirring up deep water, possibly sparking a plankton bloom in its wake.

What about climate change?

News of the iceberg's peregrination comes after record warm temperatures and low levels of sea ice have been recorded around Antarctica in recent years.

"In February 2023, sea ice around Antarctica reached the lowest extent ever observed since the start of the satellite record in 1979," the NASA Earth Observatory said.

And in September, researchers at the National Snow and Ice Data Center reported the lowest winter maximum extent of Antarctic sea ice. It was found to be nearly 400,000 square miles below the previous low, set in 1986.

"But despite several recent years of low extents, the long-term trend for sea ice in southern polar waters is essentially flat," the NASA Earth Observatory said, adding, "it is the declines in sea ice at the other pole — in the Arctic — that are pushing the global sea ice trend downward."

Scambos agrees, noting that A23a came from a part of Antarctica that is fairly stable.

"These big icebergs are spectacular, but they're just the way Antarctica works. This is how an ice sheet works. It gathers snow, and the snow thickens and flows off into the ocean, and then pieces break off. And in Antarctica, those pieces are really, really large," he said.

"But the more important thing for people to be aware of is that Antarctica in other places is losing ice very rapidly," Scambos said, describing a dynamic that contributes to rising sea levels.

"And that actually is a much more serious problem."

Hop onto TikTok and you'll find lots of videos of young people — mostly women — fake baking under the glowing UV lights of a tanning bed. Seattle dermatologist Heather Rogers says this is an alarming trend that comes after years of decline in indoor tanning in the U.S.

She points to a 2025 survey from the American Academy of Dermatology which found 20% of Gen Z respondents prioritize getting a tan over protecting their skin. And 25% say it's worth looking great now even if it means looking worse later.

They feel like "it's better to be tan than it is to worry about skin cancer," Rogers says.

A new study in the journal Science Advances reinforces just why they should worry.

Researchers found that tanning bed users were nearly three times as likely to develop melanoma — the deadliest form of skin cancer — compared to people who'd never tanned indoors. They also had DNA damage that can lead to melanoma across nearly the entire surface of the skin.

"Even in skin cells that look normal, in tanning bed patients, you can find those precursor mutations" that lead to melanoma, says Dr. Pedram Gerami, one of the study's authors and the IDP Foundation professor of skin cancer research at Northwestern University.

Gerami and his collaborators compared the medical records of nearly 3,000 patients who used tanning beds to an age-matched control group of patients who didn't tan indoors. They found that the more people used the tanning beds, the higher their risk of melanoma.

"If they had 10 to 50 tanning bed exposures, their risk was twice as high as the control group," Gerami says. If they had over 200 tanning bed visits, their risk was more than eight times as high.

"If you think about it, getting 200 tanning bed exposures can happen really quickly. If you go once a week for four years, there you are," he says.

The researchers also performed genetic sequencing on normal skin cells from tanning bed users. Most were younger women, which makes sense, because studies have shown that young women in their teens and 20s are the heaviest users of indoor tanning, says study co-author Hunter Shain, an associate professor of dermatology at the UC San Francisco.

Shain says when the researchers compared these skin samples to normal skin cells from people in the general population who were twice the age of the indoor tanners, they were "stunned" by what they found.

"Women in their 30s and 40s had more mutations than people in their 70s and 80s from the general population," says Shain, whose research focuses on the biology of skin cancer. "They somehow were able to cram in two lifetimes' worth of UV damage in 30 years."

Dr. Heather Rogers, who was not involved in the study, notes that tanning beds can emit ultraviolet radiation that is 10 to 15 times stronger than what you'd get from the sun. She says that tanning beds are often marketed as being safer than the sun, but this study shows how wrong those claims are.

Dr. Pedram Gerami says many of the patients he sees at a high-risk melanoma clinic are women who started indoor tanning as teens wanting to look better for events like homecoming and prom.

"Now, as young adults, they're having to deal with frequent skin checks, frequent doctor visits, frequent biopsies, lots of anxiety, and the emotional burden of having been diagnosed with cancer at a young age," Garami says. "So they have a lot of heaviness to deal with."

He says some of these patients chose to donate skin samples to the study in hopes of helping other young people avoid the same fate.

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Nearly every pop music holiday song written in the past 80 years owes at least some of its DNA to one Christmas tune in particular: "White Christmas," written by Irving Berlin and sung by Bing Crosby, which he first recorded in 1942.

It's reportedly still one of the best-selling songs of all time in any genre, though chart data from decades ago is unreliable. Even given that murkiness, the Guinness Book of World Records named it as the best-selling physical single of all time in 2012.

"White Christmas" wrote the formula for modern secular holiday songs — despite its complex and troubling history.

Songwriter Irving Berlin wasn't destined to be a Yuletide magic maker. He was born Israel Baline in Siberia to an Orthodox Jewish family; his father was a cantor turned kosher butcher. But Berlin embraced assimilation — he married an Irish Catholic woman and had Christmas trees in his house. Even so, for Berlin, Christmas was a holiday shadowed by personal tragedy.

"On Christmas Day, 1928, his only son died. He always told members of his family that he disliked Christmas for this reason, that he could never, never get past the sadness that he experienced on Christmas Day," said author and New York Times contributing writer Jody Rosen, who wrote a book called White Christmas: The Story of an American Song.

The infant Irving Berlin Jr. died suddenly, less than a month after he was born. And at its heart, "White Christmas" is a deeply melancholic song.

Most Christmas carols and pop songs were unabashedly joyful. Berlin's song represented a turn, Rosen said: "It was strange to have a song that was all about this nose-pressed-up-to-the-glass feeling."

It also set a certain standard for Christmas songs that are about nostalgia, about some lost Christmas past. (Think, for example, of another enduring hit that came shortly after Berlin's smash: "Have Yourself A Merry Little Christmas," which Judy Garland sang in the 1944 film Meet Me in St. Louis, and which was written by Hugh Martin and Ralph Blane.)

But there's other stuff going on too. Irving Berlin was a hit machine as a Tin Pan Alley and Broadway songwriter. As a New Yorker and an immigrant himself, he was intimately familiar with a particular genre of songs, Rosen said: "That tradition of so-called 'home songs,' you know, songs that pine for a lost place, a lost ideal. These songs are so huge because we have an immigrant population, lots of people who've done a lot of moving. So there were songs about Irish people longing for Ireland and Italians longing for the old country there."

He said Berlin took that genre and flipped it into a Christmas song.

That's especially true of a largely forgotten, tongue-in-cheek introductory verse Berlin originally wrote for "White Christmas." The narrator is a New Yorker stuck in California (as Berlin frequently was, churning out songs for Hollywood): "The sun is shining, the grass is green, the orange and palm trees sway ... but it's December the 24th, and I am longing to be up north!" the protagonist sings.

Rosen said most people listening to "White Christmas" are missing additional subtext. He said that much of that nostalgic vibe in "White Christmas" — all that longing for a pristine, innocent Christmas of yore — is a reference to explicitly racist minstrel songs like Stephen Foster's "Old Kentucky Home," sung by Al Jolson and others — music that was still a staple in Berlin's day.

Foster was inspired by the Harriet Beecher Stowe novel Uncle Tom's Cabin and the song, hailed by Frederick Douglass and Paul Robeson, was meant to be empathetic to the abolitionist cause — the narrator is longing to be reunited with his wife and children, but their family has been torn apart by slaveholders. It later became a popular tune at minstrel shows, with its saddest lines omitted and its meaning twisted.

In "Old Kentucky Home," Rosen said, "You have, grotesquely, the freed Black man longing for life back below the Mason-Dixon line, back on the plantation. Here, instead of a Black man in the north longing for the sultry south, we have a well-to-do white person longing for the wintry north."

But the racial dynamics of "White Christmas" aren't just a matter of subtle references to older songs. Irving Berlin had great commercial expectations for "White Christmas." He built a whole movie around it: 1942's Holiday Inn, starring Bing Crosby and Fred Astaire.

Holiday Inn is stuffed with racist stereotypes and an entire blackface number. (That scene is usually excised from TV broadcasts today, but the whole film is available to stream online.) As Crosby and his love interest, played by Marjorie Reynolds, prepare to perform a song about Abraham Lincoln, Crosby spreads greasepaint on her face, as the orchestra plays "White Christmas" underneath. Not only is "White Christmas" the movie's biggest hit, it's also the film's romantic theme.

Blackface on stage and on screen was very much a recent memory for 1940s audiences, said scholar Brynn Shiovitz. She's the author of the book Behind the Screen: Tap Dance, Race, and Invisibility During Hollywood's Golden Age.

In Holiday Inn, Shiovitz said, "We get a pairing of nostalgia for Christmas, but also nostalgia for blackface, because so many of the people that were watching Holiday Inn when it premiered in the theaters grew up watching vaudeville, grew up watching their parents maybe even perform in blackface."

Audiences loved the song "White Christmas" and its spotlight in Holiday Inn — and American GIs stationed abroad during World War II clamored for the Armed Forces Radio Service to play the song. "White Christmas" was so sturdily successful that Hollywood made another movie centering the song in 1954 — also called White Christmas — this time starring Bing Crosby, Danny Kaye, Rosemary Clooney and Vera-Ellen.

Since then, legions of musicians have recorded their own versions of "White Christmas" — including The Drifters, Elvis Presley, Iggy Pop and Sabrina Carpenter. And of course, each generation adds new layers of meaning to the song as it is stitched into our holiday season each year, said Shiovitz.

"With all of these other memories that people have of Christmas, whether it's being piped in while you're shopping, or it's playing on the radio in the car as you're driving to visit family — it's easy to kind of separate it from its history. People develop new memories with it. People have their own ideas of what the song represents, so it's just incredibly complex," Shiovitz said.

Today's audiences and artists don't necessarily hear or even know about the song's racist history, Shiovitz said — but that doesn't mean it's not there.
This story was edited for radio and digital by Jennifer Vanasco.
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