Reconstructing Late Miocene Arctic Climate from North Greenland Speleothems

Reconstructing terrestrial climate conditions in the high Arctic during the Late Miocene (∼11.6–5.3 Ma) is essential for understanding how polar environments respond to warmer-than-present global climates. However, direct land-based climate archives from the Arctic are rare, limiting understanding of terrestrial climate sensitivity under greenhouse-gas concentrations comparable to present and near-future conditions. Here we present a terrestrial proxy record from speleothems collected in a cave in eastern North Greenland (∼80.3°N). Speleothem growth phases indicate repeated intervals of sustained permafrost absence, implying significantly warmer and wetter conditions than today under moderate atmospheric CO₂ forcing and elevated regional sea-surface temperatures. Trace-element variability further suggests episodic glaciation in North Greenland during the Late Miocene, pointing to a highly dynamic cryosphere. Together, these results highlight pronounced terrestrial climate variability in the Arctic under warm background conditions broadly relevant to future climate trajectories. This new archive provides an important benchmark for assessing high-latitude climate sensitivity and feedbacks in a warming world.