The grooves themselves tell a story of ice far more extensive than previously believed
Dieciocho mil años después, el fondo del Mar del Norte guarda la memoria de gigantes de hielo que surcaron sus aguas durante la última glaciación. Investigadores del British Antarctic Survey hallaron, casi por casualidad entre datos de exploración petrolera, surcos en forma de peine grabados en el lecho marino por icebergs tabulares del tamaño de ciudades. Estos vestigios no solo amplían nuestra comprensión de la extensión real de la antigua capa de hielo británico-irlandesa, sino que ofrecen un espejo en el que leer el destino de los hielos antárticos actuales.
- Surcos gigantescos en el fondo del Mar del Norte revelan que icebergs del tamaño de ciudades rozaron las costas británicas hace 18.000 años, reescribiendo el mapa de la última glaciación.
- El hallazgo surgió por accidente: datos sísmicos recopilados para exploración de petróleo y gas escondían una firma geológica que nadie había buscado allí.
- La capa de hielo británico-irlandesa resultó ser mucho más vasta de lo que los modelos anteriores sugerían, lo que obliga a revisar décadas de reconstrucciones paleoclimáticas.
- El patrón de fragmentación de aquellos icebergs antiguos replica con inquietante fidelidad lo que hoy ocurre en las plataformas de hielo de la Antártida.
- El estudio, publicado en Nature Communications, convierte el pasado geológico en una herramienta para anticipar cómo el calentamiento actual podría desencadenar colapsos similares en el futuro.
Hace dieciocho mil años, cuando gran parte de Europa permanecía sepultada bajo el hielo, masas de hielo colosales se desplazaban por las aguas frente a las costas británicas. Hoy, los científicos han encontrado las cicatrices que dejaron: surcos enormes grabados en el lecho del Mar del Norte, cada uno testimonio de un iceberg del tamaño de una ciudad arrastrándose por el fondo oceánico.
El descubrimiento fue fortuito. Investigadores del British Antarctic Survey analizaban datos sísmicos de exploración petrolera en la cuenca Witch Ground cuando detectaron algo inesperado: surcos con forma de peine esculpidos en el suelo marino. El geofísico marino James Kirkham los identificó de inmediato como la huella de icebergs tabulares, masas de hielo de cima plana que podían extenderse decenas de kilómetros. Los resultados, publicados en Nature Communications, constituyen la evidencia más clara hasta la fecha de que icebergs de semejante magnitud navegaron cerca del Reino Unido durante el último período glacial.
Lo verdaderamente revelador no es solo la existencia de esos icebergs, sino su ubicación. Los surcos demuestran que la capa de hielo británico-irlandesa fue mucho más extensa de lo que se creía, proyectando hielo hacia el océano a una escala que transformó la plataforma continental. Además, el modo en que aquellos gigantes se fragmentaron progresivamente —dejando canales cada vez más estrechos— refleja con precisión los procesos que hoy se observan en la Antártida, donde las plataformas de hielo muestran señales de colapso acelerado.
El hallazgo recuerda que la última glaciación no fue un período de quietud helada, sino un sistema dinámico donde enormes masas de hielo se desprendían, derivaban y marcaban el fondo del mar. Esas marcas permanecen intactas en el sedimento, a la espera de quien tenga las herramientas y las preguntas adecuadas para descifrarlas. A veces, la historia de la Tierra se revela donde menos se la busca.
Eighteen thousand years ago, when much of Europe lay buried under ice, something massive moved through the waters off the British coast. Researchers studying the North Sea floor have now found the scars it left behind—enormous grooves carved into the seabed, each one a record of an iceberg the size of a city grinding across the ocean bottom.
The discovery emerged almost by accident. Scientists from the British Antarctic Survey were sifting through seismic data collected for oil and gas exploration in the Witch Ground basin when they noticed something unexpected: distinctive comb-shaped furrows etched into the seafloor. James Kirkham, the marine geophysicist leading the work, recognized them immediately as the handiwork of tabular icebergs—flat-topped masses of ice that could stretch for tens of kilometers across. The findings, published in Nature Communications in 2025, represent the clearest evidence yet that icebergs of this magnitude drifted close to Britain during the last glacial period.
What makes this discovery significant is not merely that such icebergs existed, but where they existed. Previous research had documented similar scour marks in other parts of the North Sea, but this is the first clear proof that enormous ice masses also traveled the waters near the United Kingdom. The grooves themselves tell a story: they show that the British-Irish ice sheet was far more extensive than scientists had previously believed, pushing ice out into the ocean on a scale that reshaped the continental shelf.
The pattern visible in these ancient scars offers more than historical curiosity. The way the massive icebergs eventually fragmented—breaking into progressively smaller pieces and creating narrower channels as they deteriorated—mirrors processes happening today in Antarctica. As ice shelves in the Southern Ocean show signs of accelerating breakdown, the North Sea record provides a natural experiment in how such systems evolve and collapse. Understanding how ice behaved thousands of years ago when the climate was warming naturally helps scientists model what might happen as human-driven warming continues.
The research also reshapes our understanding of the ice age itself. Rather than a static period of frozen stability, the last glaciation emerges as a dynamic system where enormous masses of ice calved from continental sheets, drifted across open water, and left their mark on the seafloor. Those marks remain visible today, preserved in the sediment, waiting for someone with the right tools and the right questions to read them. The accidental discovery in oil exploration data is a reminder that the Earth's history is written everywhere—sometimes we just need to be looking in the right place when we stumble across it.
Notable Quotes
The grooves were identified as the work of tabular icebergs—flat-topped masses of ice that could stretch for tens of kilometers across— James Kirkham, marine geophysicist, British Antarctic Survey
The Hearth Conversation Another angle on the story
How do you even see something like that on the seafloor? It's not as if you can dive down and photograph it.
The seismic data does the work for you. It's the same technology oil companies use to map rock layers and find deposits. Sound waves bounce off different materials, and the patterns tell you what's down there. In this case, the grooves showed up as distinctive features in the data.
So they weren't looking for ice age evidence at all?
Not at all. They were hunting for fossil fuels. The icebergs had been gone for 18,000 years, but their fingerprints were still there in the sediment. It's one of those moments where you find something far more interesting than what you set out to find.
What does it mean that the ice sheet was bigger than we thought?
It means the ice didn't just sit on land. It extended far enough out into the ocean to calve these enormous tabular icebergs—pieces tens of kilometers wide. That's a different picture of the glacial landscape than we had before. It suggests the ice was more dynamic, more aggressive in reshaping the coastline.
And the connection to Antarctica now—is that just a comparison, or does it actually help us predict what happens next?
It's both. The way those ancient icebergs fragmented and broke apart as the climate warmed gives us a template. We're watching similar processes in Antarctica today, but in real time. If we understand how ice systems responded to warming in the past, we have a better chance of understanding what's coming.
Do these grooves tell us anything about how fast things changed back then?
The pattern of fragmentation does. You see the large grooves first, then progressively smaller channels as the ice broke apart. That sequence suggests a transition period—not instantaneous collapse, but not gradual either. Something in between. That's useful information when we're trying to model future scenarios.