Issue 6/2026, News
Why does red water flow from a glacier? The mystery of Blood Falls explained
Aug
Brine, iron, and microorganisms. This remarkable combination turned out to be the key to understanding the origin of Blood Falls in Antarctica. Scientists from California examined the water flowing from Taylor Glacier and discovered a fascinating ecosystem that offers new insights into the hidden world beneath the ice sheet and the extraordinary resilience of the organisms that live there.
Blood Falls: a remarkable sight in the land of ice
The famous explorer Ernest Shackleton described Antarctica as a landscape of monumental mountains, glaciers, and ice cliffs. Yet not every part of it glows with dazzling white. A blood-red cascade flows from Taylor Glacier in the McMurdo Dry Valleys and plunges dramatically into Lake Bonney. Where does the red water come from?
Blood Falls has fascinated scientists for decades. In the second half of the 20th century, researchers established that the glacier’s striking red color results from the unique chemical composition of the brine emerging from a crack in the ice. The water is hypersaline and exceptionally rich in iron.
Where did the red water beneath Taylor Glacier come from?
The iron compounds in the brine oxidize when exposed to air, producing the characteristic rusty-red color. But why is Blood Falls salty when it lies more than 60 km from the Ross Sea?
Research conducted during the first two decades of the 21st century revealed that a reservoir of brine lies about 400 m beneath Taylor Glacier. It is connected to the surface through a network of channels and fractures. The water remains liquid despite a temperature of -7°C. How is that possible? The high salt concentration and the pressure exerted by the glacier prevent it from freezing.
Even more intriguing, an entire ecosystem exists beneath Blood Falls. Scientists discovered a diverse community of microorganisms living in complete darkness and without oxygen, obtaining energy from chemical reactions involving iron and sulfur.
The mystery of Blood Falls under the microscope
A study by California researchers, published on August 3, 2026, in the journal Nature Geoscience, sheds new light on the origin of Blood Falls. The scientists collected 167 water, sediment, and aeolian samples from the McMurdo Dry Valleys and nearby marine sites to investigate the microorganisms living beneath the ice.
Laboratory analysis identified a distinct marine microeukaryotic community that is markedly different from the Dry Valleys environment but shows a clear affinity with the ocean. According to the researchers, the presence of a relict marine community so far inland suggests the enormous scale of ancient flooding events.
The evidence indicates that during a warmer climatic period, seawater flooded Taylor Valley. As sea level later fell, the water became trapped beneath the advancing glacier. This event may have occurred more than one million years ago, when the Antarctic ice sheet was much smaller.
Andrew E. Allen, co-author of the study and a microbial ecologist at the University of California, San Diego, emphasizes the extraordinary resilience and adaptability of these ancient microorganisms, which survived despite dramatic environmental changes. Further genetic research is expected to help determine exactly when Taylor Glacier expanded and sealed the brine beneath the ice.
The latest research on Blood Falls provides evidence of a self-sustaining microbial ecosystem, suggesting that life can persist under extreme conditions for extraordinarily long periods.
Source:
Zoumplis, A., Füssy, Z., Kaul, D. et al. Molecular evidence for a relict marine community in an Antarctic Dry Valleys subglacial brine-fed system. Nat. Geosci. (2026). https://doi.org/10.1038/s41561-026-02054-6
