Chronological control and centennial-scale climatic subdivisions of the Last Glacial Termination in the western Mediterranean region

The Last Glacial Termination is marked by changing environmental conditions affected by abrupt and rapid climate oscillations, such as Heinrich Stadial 1 (HS1), which is characterized by extremely low sea surface temperatures (SST) and significant changes in northern hemisphere terrestrial landscape (e.g., vegetation) and human dispersion. 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 the Padul wetland (southern Iberian Peninsula), supported by a high-resolution chronology and contrasted with other records from southern Europe and the Mediterranean region, shows 1) that the age boundaries of HS1 in this area occurred at ∼18.0 kyr BP (median age = 17,970 cal yr BP; mean age = 18,030 ± 330 cal yr BP) and ∼15.2 kyr BP (median age = 15,210 cal yr BP; mean age = 15,200 ± 420 cal yr BP) and 2) 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 pollen sampling resolution with respect to previous studies on the same Padul-15-05 sedimentary core 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 relatively humid middle phase (HS1b; ∼17.2–16.9 kyr BP), and iii) 3 sub-phases (c.1-c.3) during an arid late phase (HS1c; ∼16.9–15.7 kyr BP). This climatic subdivision is regionally supported by SST oscillations from the Mediterranean Sea, suggesting a strong land-sea coupling. A cyclostratigraphic analysis of pollen data between 20 and 11 kyr BP indicates that the climate variability and the proposed subdivisions characterized by ∼2000 and ∼800-yr periodicities could be related to solar forcing controlling climate in this area.