Biomarker analyses on sediment core BP00-07/07 from the southern Kara Sea (Arctic Ocean)

The Holocene is characterized by the late Holocene cooling trend as well as by internal short-term centennial fluctuations. As Arctic sea ice acts as a significant component (amplifier) within the climate system, investigating its past long- and short-term variability and controlling processes is beneficial for climate future predictions. This study presents the first biomarker-based (IP25 and PIP25) sea ice reconstruction from the Kara Sea (Core BP00-07/07), covering the last 8 ka. These biomarker proxies reflect conspicuous short-term sea ice variability during the last 6.5 ka that is identified unprecedentedly in the source region of Arctic sea ice by means of a direct sea ice indicator. Prominent peaks of extended sea ice cover occurred at ~3, ~2, ~1.3 and ~0.3 ka Spectral analysis of the IP25 record revealed ~400- and ~950-year cycles. These periodicities may be related to the Arctic/North Atlantic Oscillation (AO/NAO), but probably also to internal climate system fluctuations. This demonstrates that sea ice belongs to a complex system that more likely depends on multiple internal forcing.