Climatic subdivision of Heinrich Stadial 1 based on centennial-scale paleoenvironmental changes observed in the western Mediterranean area

Abstract. Heinrich Stadial 1 (HS1) is one of the most extreme climate periods of the last glacial cycle, generating extremely low sea surface temperatures (SST) and significant changes in terrestrial landscape (e.g., vegetation). Previous studies show that overall cold/dry conditions occurred during HS1, but the lack of high-resolution records precludes whether climate was stable or instead characterized by instability. A high-resolution paleoclimatic record from Padul (southern Iberian Peninsula), supported by a robust chronology, shows that climate during HS1 was non-stationary and centennial-scale variability in moisture is superimposed on this overall cold climatic period. In this study we improve the resolution and suggest a novel subdivision of HS1 in 7 sub-phases, including: i) 3 sub-phases (a.1–a.3) during an arid early phase (HS1a; ∼18.4–17.2 kyr BP), ii) a humid middle phase (HS1b; ∼17.2–16.7 kyr BP), and iii) 3 sub-phases (c.1–c.3) during an arid late phase (HS1c; ∼16.7–15.6 kyr BP). This climatic subdivision is regionally supported by SST oscillations from the Mediterranean Sea, suggesting a strong land-ocean relationship. A cyclostratigraphic analysis of our pollen data indicates that HS1 climate variability, and thus this subdivision, is characterized by &sim:2000 and ∼800-yr periodicities, suggesting solar forcing controlling climate in this area.