At a gathering of the University of Bristol Spelaeological Society in a pub in 2008, caver Charlie Self PhD student Gina Moseley a photograph of a cave in a limestone cliff just beyond the north-western edge of the Greenland ice sheet. Thought to be the northernmost cave in the world, it had been photographed from a US military aircraft in 1958, but never explored.

But Self also gave Moseley a report about calcite flowstone, formed by trickling water, that was found in a cave in north-eastern Greenland. Today, groundwater there is frozen in permafrost, so this flowstone must have come from a warmer, wetter time. A sample could provide a climate record exceeding the 130,000 years in Greenland ice cores, Moseley thought.

Starting in 2015, Moseley and her partner, photographer Robbie Shone, mounted four expeditions to Greenland, finally reaching that northernmost known cave, pictured above. While they didn’t find any flowstone there, they did obtain some from caves in north-eastern Greenland that showed the ground there hadn’t frozen – and vegetation had even grown – during three periods between 5 million and 10 million years ago.

It was a snapshot of a past world, but also a warning about how drastically global warming could alter Greenland in the future.

“This occurred in a world with CO2 levels that we already surpassed several decades ago,” says Moseley.

In the top image, expedition member Chris Blakeley stands in the entrance of the northernmost known cave, found on the Wulff Land peninsula, after rappelling down. Below, Blakeley explores a cave in north-eastern Greenland named Crystal Palace for the hoarfrost on its ceiling.

Below, Blakeley sits in Keyhole cave, named for the shape of its entrance, where the team collected two flowstone samples.

Shone calls the caves “time machines” that may be some of the last unexplored places on Earth, as there are no current Inuit settlements in north-eastern Greenland. But the team nonetheless witnessed the effects of human-made climate change there, including summer temperatures of 16°C.

“By early evening, after a full day of sunshine on the ice cap, the rivers were huge, they were bursting and they were brown,” says Shone. “You could physically see how much water had melted on the ice cap.”

Below, the team explores another cave in the area, after a 6-metre vertical climb to get into it. A huge coating of blue ice was found on the cave’s back wall.

In the final image, below, Blakeley and researcher Gabriella Koltai scramble to board a helicopter hovering near a cave in the Wulff Land peninsula before a storm arrives. The team named the cave R66 after the model of helicopter that rushed them out of there.

Feedback is our weekly column of bizarre stories, implausible advertising claims, confusing instructions and more

Reshape your mind

One of society’s more intractable problems is unnecessary risk-taking behaviour. People do all kinds of silly things, like gambling on horses/prediction markets (delete according to age), or yelling “I love Coldplay” in a crowded biker bar.

Surely it would be better if people just didn’t do these dangerous things. The problem is how to achieve this. Perhaps some sort of public-awareness campaign, perhaps taxes on risky activities and purchases to deter people through price, perhaps a sign on the biker bar door saying “do not pick a fight”.

Or perhaps we could all just put on some shapewear. This is the startling conclusion of a little study in , highlighted to us by news editor Alexandra Thompson while, presumably, giggling like a hyena. The study indicates that wearing shapewear can make us less likely to take risks.

Feedback isn’t normally one for doing anything so responsible as actually reporting the details of an experiment, but in this case we feel readers will demand it. The authors recruited 44 volunteers, who visited the lab on two consecutive days. On one day, each person was asked to wear compressing shapewear; on the other, they were given a loose garment. They were given tests of their interoception: their ability to perceive the internal state of their body, specifically their heartbeat and their gastrointestinal system.

The volunteers were also given a test of risk-taking called the , presented online. They were shown 32 face-down cards and had to choose how many to turn over, with some giving them positive points and others taking points away. Turning over more cards is riskier than turning over just a few.

It turns out that wearing shapewear was associated with more awareness of one’s internal body state, and with less risk-taking behaviour in the card task. The idea is that enhanced interoception gives people more opportunity to pick up on subconscious warning signals.

Feedback is honestly immediately sceptical, not least because the drop in risk-taking was apparent only for the 28 women in the study: the authors interpret this as a male-female difference in the response to compressive shapewear, whereas we suspect that shapewear might not really affect risk-taking after all.

But mostly, we can’t believe that anyone had the idea to do this in the first place. Even if we had somehow inexplicably started researching shapewear, we would never have thought of this in a million years.

Cry me a volcano

Recently, Feedback asked the big questions: are some people more prone to crying when chopping onions than others? Do people who are more sensitive to onions also have a stronger sense of smell? We reported a preliminary study with some early results.

Not that we would ever claim we are doing scientists’ work for them or anything, but based on our mailbox, this is an untapped gold mine of potential findings.

Let’s start with the idea that a better sense of smell might make you more prone to crying over onions, something the study we looked at did not support. Jackie Jones adds further disconfirming evidence. “I lost my sense of smell six years ago following treatment for cancer,” she writes. “Onions, all my life, always made my eyes hurt and run, and they still do with absolutely no sense of smell.”

Likewise, Christine Wolak is surprised “that there is any scientific uncertainty about whether different people are affected differently when chopping onions”. She reports that at family gatherings, if she starts chopping onions, it can make her eyes water so badly that someone else has to take over – inevitably “experiencing no effect at all”. In fact, her eyes are so sensitive to sulphurous chemicals that a hiking trip to the vicinity of the eruption of Kilauea was enough to bring her to tears. “People thought I was so incredibly moved by the experience,” she writes.

Christine offers an intriguing detail: “This has not always happened to me.” Only after she had laser eye surgery did onion-induced tears become a regular occurrence. “I would love to know if these are related.” On a similar note, Guy Cox reports that his late wife was, at first, unaffected by onions, until she had to swap her contact lenses for bifocal glasses and became thoroughly affected. Might contact lenses be protective?

If you don’t have easy access to contact lenses, readers Chris Evans and Jackie Jones, as well as the , all recommend storing your onions in the fridge, at least for a little while before chopping, because cold onions don’t give off the relevant volatile chemicals. Feedback is going to try that and report back.

Different strokes

It’s been a long time since we saw anything relating to the Scunthorpe problem: the fact that innocuous words can contain objectionable letter strings that may confuse moderation systems. However, a new medium for such rudenesses has come to our attention: those little boxes on social media that recommend accounts to follow.

The estimable folks at the , a British charity, found themselves recommended in the “Suggested for you” box on Meta’s Threads. Owing to the small size of the box, however, their name was stripped of the concluding “ociation”, with unfortunate results.

The Stroke Association subsequently : “Just to reiterate: we talk about medical events, not… whatever this is.”

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This unusual photograph, shot under ultraviolet light with a 13-second exposure, shows some of the damage caused on land by fishing out at sea.

Gaurav Patil’s image of a fishing net that has been carried by ocean currents and become tangled in a mangrove tree on the shore of Nandgaon village, south of Mumbai, India, has won the overall prize in the 2026 . The competition is organised by US non-profit organisation Mangrove Action Project to raise awareness of the precarious position of the world’s mangrove forests.

Mangroves less than 1 per cent of all tropical forests, but provide crucial habitat for wildlife and store up to 10 times more carbon than the same area of inland forest. Despite better recent news after decades of decline, more than half of mangrove ecosystems are to be at .

Hundreds of thousands of tonnes of lost, abandoned and discarded fishing gear litter the oceans, carried around the globe by currents and eventually getting caught up or breaking down into microplastics. This gear can severely damage mangrove ecosystems, entangling marine life and choking mangrove trees.

“This photographer has put life into a subject that normally looks dull but is deeply important for conservation. Ghost nets are a real problem,” said judge Dhritiman Mukherjee in an announcement about the prize.

Feedback is our weekly column of bizarre stories, implausible advertising claims, confusing instructions and more

Bloons and doubloons

This edition of Feedback is an exercise in time travel – in that every item is something from absolutely ages ago that we somehow missed. We would feel guilty, but it is the summer holidays (in the northern hemisphere, anyway) and many readers will have half an eye on their errant children, so we thought we could get away with it.

So, cast your minds back to 2008. This, obviously, was the year of the 20th Canadian Conference on Computational Geometry, . A large amount of research was at this conference, but reporter Matthew Sparkes recently stumbled across a by Erik Demaine, Martin Demaine and Vi Hart. It presents “a general mathematical and algorithmic theory for balloon-twisting structures”.

If you didn’t grasp that, allow us to clarify: it’s about the geometry of balloon animals. The authors develop a mathematical framework that allows them to calculate how many balloons you need to generate a particular shape, whether it is a dog (one) or some complicated polyhedron like a dodecahedron (10). These, naturally, are referred to as “Platonic balloons”.

Throughout the paper, the authors use the term “bloon” to refer to a mathematical entity equivalent to a balloon. Feedback wasn’t clear why this neologism was necessary, until we realised that they were therefore able to refer to a balloon of twice the usual length as a “doubloon”.

Curious to know what the authors had been up to since, Feedback went a-searching. Hart became a science populariser on YouTube, then a senior manager at Microsoft. Meanwhile, Martin and Erik are father-and-son researchers and artists, both fascinated by the mathematics of folding.

Erik, a professor at the Massachusetts Institute of Technology, has been in New Scientist a lot. Recent papers include “” and ““. More from Erik, please.

Testing times

Continuing on the topic of being very late to things, reader Derek Long flagged a paper from 2018, “ and major trauma when jumping from aircraft: randomized controlled trial”. It reports on a study called “PArticipation in RAndomized trials Compromised by widely Held beliefs aboUt lack of Treatment Equipoise (PARACHUTE)”.

(Side note: that is a truly excellent scientific acronym. We haven’t had any of those in a while.)

The problem posed is one of evidence. “Parachutes are routinely used to prevent death or major traumatic injury among individuals jumping from aircraft. However, evidence supporting the efficacy of parachutes is weak and guideline recommendations for their use are principally based on biological plausibility and expert opinion.” If readers haven’t yet twigged: the paper is satirical, poking fun at the idea that even the most common-sense interventions should be tested in a full randomised controlled trial.

As the authors write: “In seminal work published in the BMJ in 2003, a systematic search by Smith and Pell for randomized clinical trials evaluating the efficacy of parachutes during gravitational challenge yielded no published studies.”

Feedback actually ran across that back in 2004. The authors noted they were “unable to identify any randomised controlled trials of parachute intervention” and suggested that “everyone might benefit if the most radical protagonists of evidence based medicine organised and participated in a double blind, randomised, placebo controlled, crossover trial of the parachute”. Oof.

Fifteen years later, they did do a trial. This showed that “parachute use did not significantly reduce death or major injury”, with the slight caveat that “the trial was only able to enroll participants on small stationary aircraft on the ground”. This was helpfully illustrated by a photo of one of the participants jumping, parachute-less, out of a grounded plane. As the authors say: “Our findings should give momentary pause to experts who advocate for routine use of parachutes for jumps from aircraft in recreational or military settings.”

Witty Zwicky

Some concepts can’t be traced back to their origins. One such is the spherical cow joke, which illustrates the difficulties of working with highly simplified and abstract models of complicated, real-world situations. It involves a physicist who figures out how to improve productivity on a dairy farm, but their solution only works for spherical cows in a vacuum. Nobody seems to know who came up with this: the oldest references place it , but the origin stories are all vague and one reference the cows with chickens.

However, another sphere-based physicist joke seems to be older. Feedback has just learned, many decades after the fact, about an insult deployed by Fritz Zwicky, who, in the 1930s, produced some of the first evidence for dark matter. A noted curmudgeon, Zwicky was fond of referring to people he disliked as “spherical bastards”. Such a person is a bastard no matter which way you look at them.

Feedback will be using that from now on. But we also want to know the etymology (if that is quite the term) of spherical bastards, chickens and cows. Any insights welcome.

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You can send stories to Feedback by email at feedback@newscientist.com. Please include your home address. This week’s and past Feedbacks can be seen on our website.