Coupled atmosphere-ice-ocean dynamics during Heinrich Stadial 2

Area of Science:

• Paleoclimatology
• Climate Dynamics
• Isotope Geochemistry

Background:

• Millennial-scale climate events, like Heinrich Stadial 2 (HS2), are crucial for understanding past climate dynamics.
• Precise phase analyses and chronological frameworks are essential for accurately reconstructing these events.
• Existing chronologies for major ice sheets may require adjustments.

Purpose of the Study:

• To present high-resolution speleothem oxygen-isotope records from monsoon regions during HS2.
• To establish a precise chronological framework for HS2, enabling detailed climate phase analysis.
• To investigate the role of low-latitude hydroclimate in millennial-scale climate variability.

Main Methods:

• Analysis of nine speleothem oxygen-isotope records.
• Sub-centennial age precision and multi-annual resolution dating techniques.
• Integration with volcanic evidence and radiocarbon ages for chronological refinement.

Main Results:

• Speleothem data suggest adjustments of +320 years for Greenland and +400 years for Antarctic ice-core chronologies.
• A synchronous global onset of HS2 is identified.
• A centennial-scale "tropical atmospheric seesaw" superimposed on the "bipolar seesaw" was observed at the HS2 onset.
• An early South American monsoon shift was detected at the HS2 termination.

Conclusions:

• The study provides a refined chronology for HS2, improving our understanding of millennial-scale climate events.
• Low-latitude hydroclimate exhibits a more active role in millennial climate dynamics than previously recognized.
• The findings imply unique hydroclimate responses and feedbacks during such events.