Blood Falls on the Taylor Glacier in Antarctica: Pressure surges drive iron-rich brine to the surface. (archive photo)Image: imago stock&people
In the middle of the eternal ice of Antarctica, blood-red water suddenly flows out of a glacier. A new study now shows for the first time what triggers the mysterious outbreaks.
July 11, 2026, 7:52 p.mJuly 11, 2026, 7:52 p.m
Ellen Ivits / t-online
In the middle of the icy landscape of Antarctica, deep red water suddenly flows over a white glacier. It remains liquid even at temperatures well below freezing. Since the Australian geologist Griffith Taylor discovered the Blood Falls in 1911, scientists have been puzzled about the unusual natural phenomenon. A new study now provides detailed insights into the eruptions of red water for the first time – and shows how the glacier changes as a result.
Researchers have long assumed that algae turns the Blood Falls red. However, it is actually caused by iron-rich brine that has been trapped under the northern end of the Taylor Glacier for at least 1.5 million years.
The reservoir was created when an ancient seawater basin was cut off from the outside world by the advance of the glacier. Since then, the salt content has continued to rise. Today it is a highly concentrated brine that remains liquid even at the sub-zero temperatures that are common in Antarctica.
When the brine finally reaches the surface, it comes into contact with oxygen for the first time in more than a million years. The iron dissolved in it oxidizes – similar to how rust occurs – and turns the escaping water deep red.
“Happy combination of observations” reveals secret
For a long time, the question of how the brine actually got to the surface from a depth of several hundred meters was at least as puzzling as the red color. It was only in 2018 that a research team from the University of Alaska Fairbanks managed to trace the path of the water using radar measurements. According to this, the brine flows through an approximately 300 meter long network of pressurized channels inside the glacier.
The one now in the trade magazine Antarctic Science The published study provides detailed insights into this process for the first time. In September 2018, researchers at Taylor Glacier almost coincidentally operated three independent measurement systems at the same time: a GPS station to measure the glacier surface, a time-lapse camera at Blood Falls, and temperature sensors in Lake Bonney below.
None of the instruments were specifically designed to observe a brine eruption. But as the authors write, a “fortunate combination of observations” meant that the event could be documented almost completely.
The Blood Falls eruptions in Antarctica
For the researchers, this results in a coherent picture: pressure builds up in the trapped brine beneath the glacier over a long period of time. If this becomes too large, the liquid presses itself to the surface in spurts. The underground reservoir briefly loses volume – and the glacier above sinks measurably while its movement temporarily slows down. The cycle then begins again.
Why the water under the glacier remains liquid
The fact that liquid water can permanently exist within the glacier is due to the high salt content of the brine. It lowers its freezing point so much that it does not freeze completely even in the extreme temperatures in the glacier. If ice still forms, heat is released. This warms the surrounding ice and prevents the canals from freezing over completely.
“Even if it sounds contradictory at first: water releases heat when it freezes, and this heat warms the surrounding, colder ice,” explained glaciologist Erin Pettit at the time. The Taylor Glacier is therefore “the coldest known glacier with permanently flowing water”.
Cut off from the outside world for 1.5 million years
The Blood Falls are not only a geological mystery, but also a biological one. Several hundred meters beneath the ice, a community of microorganisms lives in the enclosed brine – completely shielded from sunlight and the atmosphere. The reservoir has been isolated from the outside world for at least 1.5 million years.
After microbiologist Jill Mikucki managed to take a suitable sample of the brine for the first time in several years, she came across a surprisingly diverse and active microbial ecosystem. The organisms do not need sunlight or oxygen. Instead, they get their energy from chemical reactions with sulfate compounds dissolved in the brine.
This is precisely why the Blood Falls are now considered one of the most extraordinary natural laboratories on earth. Scientists use them as a model to study how life can arise and persist under extreme conditions – for example in the hidden oceans beneath the ice crusts of Jupiter’s moon Europa or Saturn’s moon Enceladus.