450,000 Years of Climate Variability: A Speleothem Composite from the Northern European Alps

Understanding continental climates across multiple glacial-interglacial cycles remains fundamentally limited by the scarcity of continuous, high-resolution terrestrial archives. During glacial periods, many terrestrial records are interrupted by prolonged depositional hiatuses. Although Greenland ice cores provide exceptional high-resolution records, they reach back only about 128,000 years, leaving earlier key climate intervals poorly constrained. Here, we present a composite record of subglacial speleothems from the European Alps spanning nearly half a million years (0-450 ka BP), providing a quasi-continuous, high-resolution record of continental climate variability supported by well-constrained chronologies.

Alpine and subglacial speleothems offer a unique paleoclimate window because they record both interglacial warmth during conventional growth phases and glacial conditions during deposition beneath ice cover, thereby capturing the full range of Quaternary climate states within a single archive type. Our Alpine composite reveals coherent oxygen isotope patterns across multiple cave systems and elevational gradients, reflecting regional-scale changes in temperature, precipitation, and moisture sources over five glacial-interglacial cycles.

Millennial-scale variability persists throughout the entire 450,000-year record, suggesting that rapid climate oscillations—often considered characteristic of the last glacial cycle—are instead a persistent feature of Quaternary glaciation dynamics. Orbital-scale forcing is clearly expressed across all cycles, albeit with notable deviations from the hemispheric trend. Most critically, beyond 250 ka BP, Alpine climate dynamics increasingly decoupled from global ice-volume signals while showing a strengthened coherence with global greenhouse gas concentrations.

Based on 37 speleothem records from 10 caves, this composite demonstrates that alpine and subglacial speleothems represent a transformative but underutilized terrestrial climate archive. Their ability to bridge the temporal gap between ice-core and marine records, combined with sub-millennial resolution and exceptional chronological control, opens new possibilities for reconstructing and understanding terrestrial climate evolution across extended Quaternary timescales.