A long-lost photo snapped from a Navy plane in 1966 has become the unlikely key to understanding how Antarctica’s ice shelves collapse—and what it means for rising seas around the world.
Scientists at the University of Copenhagen combined these forgotten aerial images with modern satellite data to track the slow but relentless disintegration of the Wordie Ice Shelf. What they uncovered turns conventional thinking upside down: it’s not surface melt but warmer ocean water eating away from below that drives the collapse.
Old Photos Expose Antarctic Ice Secrets
On November 28, 1966, an American airplane flew over the Antarctic Peninsula, just south of Chile’s southern tip. On board was a photographer, likely from the U.S. Navy, whose mission was to map the frozen landscape below.
What he captured, though, turned out to be far more important. Among the shots he took was a photo of the Wordie Ice Shelf, an enormous slab of floating ice. That very shelf would collapse almost entirely over the next 30 years.
Its collapse released a massive plug of ice, allowing the glacier behind it to flow freely into the ocean. This process can lead to rising sea levels, especially when much larger ice shelves are involved.
Ice shelves and sea level rise
Ice shelves, like Wordie, act as a kind of brake on glaciers flowing from the ice sheet towards the sea. When an ice shelf vanishes, the glaciers lose this support and can begin to float and melt more rapidly.
As the ice mass of ice shelves is already partially or wholly in the sea, their direct contribution to sea level rise is limited. On the other hand, the glacier ice they retain is on land and, therefore, every cubic metre affects the water level of the world’s oceans.
Although Antarctica is far away, areas like Denmark are being affected significantly by sea level rise caused by ice shelf collapses resulting from gravitational forces. Before Antarctica melts, its ice mass helps pull sea waters southwards. When the ice has melted into the sea, the gravitational field has changed, causing the oceans to the north to rise proportionally more.
Wordie’s Collapse and Looming Sea-Level Peril
While Wordie was relatively small, its collapse is a warning sign. Antarctica is home to giant ice shelves like Ronne and Ross, which together hold enough land-connected ice to raise global sea levels by up to five meters if they fail.
And although Antarctica may feel far away, what happens there affects coastlines around the world. Because of gravitational forces, melting ice in the Southern Hemisphere can raise sea levels in places like Denmark and beyond.
That 1966 photo became the first in a remarkable series that documented the slow disintegration of Wordie. Now, researchers at the University of Copenhagen have combined these historical aerial images with modern satellite data to create the most detailed, time-lapsed view ever of an ice shelf collapse.
Published in Nature Communications, their study reveals how these collapses unfold over time. The data offers scientists a powerful new tool to detect early warning signs of collapse and better understand the forces that are reshaping Antarctica—and threatening coastlines across the globe.
Time-Series Dataset Revolutionizes Predictions
“We have identified several signs of incipient ice shelf collapse that we expect will be observed in other ice shelves, but perhaps more importantly, the dataset has given us a multitude of pinning points that can reveal how far advanced a collapse is. It’s a completely new tool that we can use to do reality checks on ice shelves that are at risk of collapsing or already in the process of collapsing,” says Postdoc Mads Dømgaard from the Department of Geosciences and Natural Resource Management, who is the lead author of the study.
According to the researchers, this knowledge will enhance computer models of sea level rise and lead to more accurate predictions of when the water will rise, allowing for prioritization of investments in climate change adaptation in the most effective way.
Facts: How dusty old photos became important data
In the study, the researchers used images from multiple overflights of Wordie, shot between 1966 and 1969.
In analyzing the historical aerial photos, the researchers employed the structure-from-motion photogrammetry method, which utilises overlapping photos to calculate accurate three-dimensional models of landscapes or objects.
By analyzing differences in perspective between the photos, it’s possible to measure heights and distances with high accuracy. This allows tracing how the ice surface, thickness and velocity have changed over time.
Photogrammetry Reveals Under-Ice Melting
The hundreds of historical aerial photos were analyzed using a technique known as structure-from-motion photogrammetry. The method has enabled scientists to accurately reconstruct ice thickness, as well as its extent, surface structure, and flow velocity, dating back to the 1960s.
In this way, the researchers analyzed the collapse of Wordie and learned more about the factors involved. It was previously assumed that a warmer atmosphere was the primary factor leading to the collapse, and, similarly, that the formation of meltwater lakes on the ice surface had also played a part. The new study has disproved both assumptions.
Instead, the researchers highlight melting under the ice where the sea and ice meet as definitive factors.
“Our findings show that the primary driver of Wordie’s collapse is rising sea temperatures, which have generated the melting beneath the floating ice shelf,” Mads Dømgaard says.
Slow-Motion Failures Heighten Long-Term Risks
Furthermore, the study’s findings have already altered the foundation of scientists’ knowledge about ice shelf collapse. According to co-author Anders Anker Bjørk, the new data advances our understanding of how and at what speed these collapses occur.
“The tentative conclusion from our findings is that ice shelf collapse may be slower than we thought. This means that the risk of a very rapid development of violent sea level rise from melting in Antarctica is slightly lower, based on knowledge from studies like this one,” says Anders Anker Bjørk, Assistant Professor at the Department of Geosciences and Natural Resource Management.
But there is also a flip side to this, he explains:
“It was already a supertanker that needed to be turned to stall the melting of ice in Antarctica, but our data shows a collapse process that is even more protracted than previously assumed. And this longer process will make it harder to reverse the trend once it has started. This is an unambiguous signal to prioritise halting greenhouse gas emissions now rather than sometime in the future,” Anders Anker Bjørk says.
Reference: “Half a century of dynamic instability following the ocean-driven break-up of Wordie Ice Shelf” by Mads Dømgaard, Romain Millan, Jonas K. Andersen, Bernd Scheuchl, Eric Rignot, Maaike Izeboud, Maud Bernat and Anders A. Bjørk, 29 April 2025, Nature Communications.
DOI: 10.1038/s41467-025-59293-1
Never miss a breakthrough: Join the SciTechDaily newsletter.
Follow us on Google and Google News.
9 Comments
“Although Antarctica is far away, areas like Denmark are being affected significantly by sea level rise caused by ice shelf collapses resulting from gravitational forces.”
I thought that Scandinavia was experiencing isostatic rebound, meaning that the land is rising, creating a situation where the net result was sea level falling compared to the land.
One might suppose that the rate of isostatic rebound is less than the rate of rise in sea level. I know neither rates.
The mistake is believing sea level rise is the ultimate concern when inland flooding will devastate from within faster than rising sea levels. Why? While Antarctica ice might melt and fall into the ocean, sea level rise will be a problem but that excess water will precipitate over inland land, flooding from within faster than sea level rise
“This is an unambiguous signal to prioritise [sic] halting greenhouse gas emissions now rather than sometime in the future,”
Once again the melting is being attributed entirely to CO2, specifically anthropogenic CO2, which we have some control over, at the cost of turning our energy industry and economies on their head, with reasons to believe it will not have the desired result.
This is despite the fact that they have provided evidence that West Antarctica ice melting ISN’T resulting from the atmosphere warming! Rather, it is melting from the bottom up from old water that is cold and dense. An alternative hypothesis that is being ignored is that geothermal heating from submarine volcanoes is responsible for the melting, not tropospheric CO2. The water is already so close to the freezing/melting temperature that it wouldn’t take much warming to cross the threshold. How can someone tell us with a straight face that CO2 needs to be curtailed when they present evidence that is isn’t warming air that is responsible for West Antarctic ice melting?
What are you talking about? You don’t even seem to understand the most basic concepts related to the planets energy balance, how heat travels through the system or which way is up.
CO2 is insulating and slows the rate at which heat can radiate out to space. Literally no one thinks that is the only thing that increases the planets temperature. Why would you even pretend that was a scientific debate anywhere?
The idea that you would weigh in on a topic like this when you don’t even seem to know that heat rises or that the ocean is warmest at the surface is just sad. I can’t even imagine how someone could not know such easily observable facts.
The main ocean currents are driven by the very simple fact that most heat from the sun goes to the equator and flows to the poles where it escapes into space. A warmer planet means more heat has to travel to the poles. That’s why we’re getting more atmospheric rivers and why they travel towards the poles faster every year.
Warm surface water flows to the poles where it releases its heat and freezes. The salt doesn’t freeze and instead a current of extra cold salty water flows straight down to the bottom and heads back to the equator to pick up more heat before a return trip to the poles.
Use your brain and take the few basic science facts you can see with your own eyes. You can’t let other people think for you and you wouldn’t have come up with that post if you’d put any thought or even a 5th grade education into your “theories”
The reason I can call you out with a straight face is because you’re either playing the fool or you truly are. The planet is getting hotter every year. It’s about to melt the ice caps which will disrupt the ocean currents. If we don’t want that to happen we need to reduce the CO2 in the atmosphere so heat can escape faster. Pretending that earth’s heat in the ocean and in the air aren’t the exact same thing in regards to our planets energy balance is a frustrating example of the lack of basic science and math skills they teach in elementary school. You are literally unable to figure out where the equal sign goes in a basic equation but insulting everyone who is talking about what that equation tells us. I’m embarrassed for you but dismayed at schools that can’t seem to teach even the most basic math to some people.
Eric, you come across as rude and pretentious and not all that smart.
Most CO2 also goes into the ocean so not only does the heat in the air get stored in the oceans but that co2 also makes the oceans more acidic.
Your argument is like claiming the CO2 in your yard isn’t warming the poles and therefore we just have to ignore the problem.
“the heat in the air get stored in the oceans ”
Bwahaha..
The ocean heats the air, not the reverse.
I can’t believe this fundamentally flawed junk science still has so many gullible followers
we need more CO2 in the air, at the end of the last ice age levels had fallen to 182ppm, 150ppm is an extinction level event, all vegetation would die
evolution tells us the route to survival is adaptation, not sticking your head in the sand