Past polar sea ice variability

Sea ice is a fundamental component of the Earth's climate system. Changes in sea ice extent and thickness have a strong influence on albedo, the hydrologic cycle, ocean and air currents, ocean-atmosphere energy exchange, water mass stratification and formation, and biological productivity. Accurate documentation of past sea ice variations is a significant prerequisite for understanding the interactions between the ice, ocean, and atmosphere and their influence on climate change.

AWI has a long-standing expertise in micropaleontological and, more recently, biomarker-based reconstruction of sea ice, which provides important information on:

•     natural (non-anthropogenically induced) sea ice variability and associated climate variability;
•     Changes in marine primary production induced by changing sea ice conditions;
•     Multi-proxy comparisons and proxy-integrating model studies.

Knowledge of sea ice decline and expansion during past climate variability (e.g., during the Last Glacial Maximum, Deglacial, or Holocene) helps assess the role of sea ice as a driving mechanism for polar amplification of global climate change. In particular, complementary (multi-proxy) studies based on micropaleontological, sedimentological, and organic-geochemical methods allow a detailed investigation of ice-ocean-atmosphere feedback mechanisms and their influence on (pre)Quaternary climate variability. These data sets serve as a valuable basis for the synthesis of proxy and model approaches. At AWI, we use biomarkers (geochemical fossils) and fossil diatoms (diatoms) to reconstruct sea ice cover.