Planktonic foraminifera and sea surface temperture reconstruction for Red Sea sediment cores

In order to assess how insolation-driven climate change superimposed on sea level rise and millennial events influenced the Red Sea during the Holocene, we present new paleoceanographic records from two sediment cores to develop a comprehensive reconstruction of Holocene circulation dynamics in the basin. We show that the recovery of the planktonic foraminiferal fauna after the Younger Dryas was completed earlier in the northern than in the central Red Sea, implying significant changes in the hydrological balance of the northern Red Sea region during the deglaciation. In the early part of the Holocene, the environment of the Red Sea closely followed the development of the Indian summer monsoon and was dominated by a circulation mode similar to the current summer circulation, with low productivity throughout the central and northern Red Sea. The climatic signal during the late Holocene is dominated by a faunal transient event centered around 2.4 ka BP. Its timing corresponds to that of North Atlantic Bond event 2 and to a widespread regionally recorded dry period. This faunal transient is characterized by a more productive foraminiferal fauna and can be explained by an intensification of the winter circulation mode and high evaporation. The modern distribution pattern of planktonic foraminifera, reflecting the prevailing circulation system, was established after 1.7 ka BP.

Multi-sensor global compilation of mid-Holocene sea surface temperatures, based on Mg/Ca and alkenone palaeothermometry and reconstructions obtained using planktonic foraminifera and organic-walled dinoflagellate cyst

We present and examine a multi-sensor global compilation of mid-Holocene (MH) sea surface temperatures (SST), based on Mg/Ca and alkenone palaeothermometry and reconstructions obtained using planktonic foraminifera and organic-walled dinoflagellate cyst census counts. We assess the uncertainties originating from using different methodologies and evaluate the potential of MH SST reconstructions as a benchmark for climate-model simulations. The comparison between different analytical approaches (time frame, baseline climate) shows the choice of time window for the MH has a negligible effect on the reconstructed SST pattern, but the choice of baseline climate affects both the magnitude and spatial pattern of the reconstructed SSTs. Comparison of the SST reconstructions made using different sensors shows significant discrepancies at a regional scale, with uncertainties often exceeding the reconstructed SST anomaly. Apparent patterns in SST may largely be a reflection of the use of different sensors in different regions. Overall, the uncertainties associated with the SST reconstructions are generally larger than the MH anomalies. Thus, the SST data currently available cannot serve as a target for benchmarking model simulations.