Late Holocene climate oscillations and solar fluctuations from speleothem STAL‐AH‐1, Sauerland, Germany: A numerical perspective

Initial 14 C activity in a late Holocene stalagmite (a 14 C stal ) from Attahöhle (Sauerland, Germany) varies synchronously with atmospheric 14 C activity (a 14 C atm ). This observation provides independent chronological support for the correlation between a solar forcing proxy (atmospheric 14 C production rate, a 14 C prod ) and a climate proxy ( δ 18 O stal ) in this stalagmite, and eliminates the need to ‘tune’ the chronology. Monte Carlo randomizations in which 100,000 synthetic δ 18 O stal datasets were generated indicate that the correlation between a 14 C prod and δ 18 O stal is statistically robust. The absence of a significant time lag between a 14 C prod and δ 18 O stal implies rapid climate response at this site to variations in solar output. Positively correlated a 14 C prod ‐ δ 18 O stal indicates drier winter conditions during late Holocene solar minima. This supports atmospheric amplification models that predict reduced NAO indices during solar minima if kinetic enrichment of δ 18 O during dry phases outweighs the reduction of δ 18 O in rainfall that results from lower air temperatures during negative NAO phases.