Holocene to Late Pleistocene Climate Reconstruction: A snapshot from the Red Sea using Micropalaeontological Tools

Climate fluctuations and environmental changes have been integral to the Earth’s system since its formation. Studying these past changes could provide crucial insights into future climate variability, where records of environmental change within sediments can serve as keys to unlocking this information. Here, we focus on climatic shifts over the past 20,000 years based on micropaleontological data from sediment gravity cores collected from the Northern Red Sea near the Al-Wajh carbonate platform in Saudi Arabia. The Red Sea is located in the subtropical Sahara-Arabian Desert belt and is supplied with nutrients by dust. Due to its restricted connection with the Indian Ocean, the area is extremely sensitive to global Sea Level Changes and thus, ideally suited for paleoceanographic studies of what occurred since last glaciation.

It is generally accepted that the Sahara was green during the African Humid Period(5.5 – 11ka). Subsequently, to understand these shifts from humid, to arid periods, and vice-versa we incorporate a combination of methods applied to a marine sediment core. The present study comprises analysis of 56 sediment samples collected at an interval of 5-10 cm from the core PERC-002-018 (25°41'10.48"N, 36°21'17.59"E). The sampled core (water depth: 864m; core length: 286cm) belonged to a deep-sea fan formed by a paleo-channel called “Wadi al Hamd”. These sediment samples were examined for the coccolithophore assemblage, together with the analysis of sediment grain size and mineralogical composition. The results show a clear maximum in total coccolith number since the Mid-Holocene (>20,000 x 10⁶ coccolith/g sediment), and low but variable numbers during the Last Glacial Maximum (LGM) to the Early Holocene (~10,000 x 10⁶coccolith/g sediment). However, this trend is interrupted by a peak related to the formation of Sapropel RS-1b at the beginning of the Holocene. The variations in abundance and distribution of the 36 identified coccolithophore species indicate changes in the environment, with higher estimated productivity assumed during the Holocene. Moreover, two main humid periods have been identified from the study: (i) during the shift from Heinrich stadial 1 to the Bølling–Allerød warm period and (ii) at the start of the Holocene. The causes and shifts of these humid phases will be further discussed in detail.