Remarkable Find: Norwegian Cave Reveals Secrets of Arctic Fauna Extinct for 75,000 Years

How did the arctic species react to past climate upheavals? This question becomes crucial at a time when global warming quickly transforms polar ecosystems. A recent study, conducted by an international team bringing together the University of Oslo, Bournemouth University, the University Museum of Bergen and the Norwegian University of Life Sciences, brings elements of concrete response. Published in the Revue Proceedings of the National Academy of Sciences (PNAS), this research is based on the analysis of animal remains found in an isolated cave in northern Norway.

A window open to the Arctic of the past

Access to Arne Qvamgrotta cave, located in the county of Nordland, does not result from a scientific project. It is a mining drill made over thirty years ago. Long ignored, this cavity remained out of reach until Norwegian and British researchers initiated excavations between 2021 and 2022. This site, which remained safe from the sun and temperature variations, has preserved an exceptional biological archive in frozen soil. It can be compared to a natural freezer.

© Trond Klungseth Lødøen

The remains found, dated approximately 75,000 years, come from a period called Marine 5A isotopic stadium. Concretely, a temperate episode between two glacial phases of the Pleistocene. This era, although distant, is still poorly known in northern Europe. Arne Qvamgrotta's cave thus constitutes one of the few direct testimonies of an Arctic Environment at this period.

Scientists have uncovered more than 170 fragments of bone and teeth, belonging to at least 46 animal species, analyzed by radiation and DNA sequencing. This unusual diversity indicates the coexistence, in the same coastal environment, of terrestrial mammals such as the reindeer or the polar fox, of marine animals such as the ringed seal, the Morse or the boreal whale, but also of birds, including the puffy monk, and of fish like the cod of the Atlantic. These elements show that the cave acted as a natural trap or a refuge frequented by fauna. This unique paleontological deposit document for the first time a complete ecosystem of the Arctic High during a key climatic phase.

A softer climate … but unstable

The period revealed by the discoveries of the cave of Arne Qvamgrotta therefore corresponds to a relatively hot phase of the Pleistocene, which occurred between two glacial episodes. This moment is characterized by global warming marked to cause a temporary decline in glacial caps in Scandinavia. This allowed the emergence of an unusually rich environment for the region. Namely: a coastal tundra punctuated by rivers, wetlands and lake formations, conducive to various biodiversity.

The species found in the cave reveal an adaptation to this softer climate, but also a fragile balance. The presence of reindeer indicates seasonal terrestrial migrations. The discovery of freshwater fish, such as the cold water chabot, confirms the existence of river systems free of ice for part of the year. These favorable conditions have enabled Arctic species, now confined to high latitudes, to settle much further south than at present.

However, this climatic respite was short -lived. When temperatures have brutally relapsed, many of these species could not migrate to refuge areas. The DNA analysis of bones shows that certain genetic lines found in the cave are no longer present in current populations. This suggests local, even global extinction. Professor Sanne Boessenkool stresses that this inability to respond to rapid climate change questions the supposed resilience of Arctic fauna. “” These data show that ecological specialization can become an evolutionary trap during the instability “She explains to Eurekalert.

Missing species and fragmented ecosystem

Among the most unexpected discoveries from Arne Qvamgrotta cave is the necklace lemming (Dicrostonyx), now extinguished in Europe. Never previously reported in Scandinavia, its presence proves that the region hosted species 75,000 years ago whose distribution was much wider than currently. This little rodent, adapted to cold and dry environments, indicates a relatively stable tundra landscape, but also an ecological network today disappeared. For Dr Sanne Boessenkool, this discovery ” illustrates the extent of past arctic biodiversity, far beyond what we observe today “Reports Phy.org.

© Sam Walker

Bone fragment.

Another marking index: the presence of remains of common porpoises (Phocoena Phocoena). Indeed, this species tends to avoid the enclosed areas. Their appearance in the strata dated from the interstade 5A confirms that the Norwegian coast was, at least partially, free from seasonal ice. Species like Morse, bearded seal and boreal whale complete this painting of diversified marine fauna. A fauna dependent on a fragile balance between free sea and ice floe.

© Trond Klungseth Lødøen

Polar bear bone.

But these formerly connected ecosystems remain deeply fragmented today. Dr. Sam Walker, paleoecologist at Bournemouth University, underlines that ” Arctic species then could move to large territories without major obstacle ». On the other hand, the modern era requires borders: roads, human installations, rapid warming, he recalls. Morse, for example, already undergoes a loss of access to the essential glacial platforms for its rest. The boreal whales, on the other hand, see their migratory roads disturbed. For researchers, these comparisons illustrate a brutal decline in ecological resilience, exacerbated by contemporary human pressures.

A warning for the present

The study of the cave of Arne Qvamgrotta is not limited to natural history. It raises urgent ecological issues. By analyzing the responses of species to past climatic variations, the researchers point to a constant. Specialized species do not survive fast upheavals. Professor Sanne Boessenkool affirms it bluntly at Mirage News. “” What we observe is the limited resilience of specialized species in the face of rapid upheavals ».

At the documented time, it was a brutal cooling. Today is the opposite: accelerated warming. However, the mechanism is the same. A rapid climate transition forces the species to adapt, migrate or disappear. The fossils of the cave show that many have not crossed this milestone in the past, even with then continuous habitats. Today, this continuity has disappeared.

Some species present in fossil layers still exist in the Arctic. But their situation is weakening. Their habitats are reduced and their biological cycles are disturbed. “” If these species suffered during cooling, how will they survive the rise in unprecedented temperatures? Asks Boessenkool. This climatic asymmetry – modern, rapid and global warming – places species in an unprecedented evolving dead end.

Norwegian discovery goes beyond scientific interest. It reintroduces the past as a warning tool for the future. By reconstructing a full ecosystem of the Pleistocene, the study provides a concrete basis to assess the current vulnerability of Arctic fauna. As sums up by Dr. Sam Walker: ” This frozen past tells us about the future ». A lucid way to connect the memory of the climate to the immediate challenges of biodiversity.

Source: Walker, Samuel J. et al., “A 75,000-y-Ob Scandinavian Arctic Cave Deposit Reveals Past Faunal Diversity and Paleoenvironment”. Proceedings of the National Academy of Sciences (2025).