Proxy data and model simulations of sediment core GeoB7920-2

The evolution of the northwest African hydrological balance throughout the Pleistocene epoch influenced the migration of prehistoric humans**1. The hydrological balance is also thought to be important to global teleconnection mechanisms during Dansgaard-Oeschger and Heinrich events**2. However, most high-resolution African climate records do not span the millennial-scale climate changes of the last glacial-interglacial cycle**1, 3, 4, 5, or lack an accurate chronology**6. Here, we use grain-size analyses of siliciclastic marine sediments from off the coast of Mauritania to reconstruct changes in northwest African humidity over the past 120,000 years. We compare this reconstruction to simulations of palaeo-humidity from a coupled atmosphere-ocean-vegetation model. These records are in good agreement, and indicate the reoccurrence of precession-forced humid periods during the last interglacial period similar to the Holocene African Humid Period. We suggest that millennial-scale arid events are associated with a reduction of the North Atlantic meridional overturning circulation and that millennial-scale humid events are linked to a regional increase of winter rainfall over the coastal regions of northwest Africa.

Neogene palaeoclimate reconstructions in Anatolia (Turkey)

Neogene basins are widespread in Turkey and contain important lignite deposits. In this study, we reconstruct quantitatively the Late Oligocene-Miocene climate evolution in western and central Anatolia by applying the Coexistence Approach to the palynoflora. The obtained results are compared with the data derived from the published and ongoing studies in western and central Anatolia palynofloras by application of the Coexistence Approach. The Coexistence Approach results show that the sedimentation mainly developed on terrestrial environment under the warm subtropical climatic conditions and marine influence during the Chattian and Aquitanian period in western Anatolia (16.5-21.3°C of mean annual temperature (MAT) and 5.5-13.3°C of mean temperature of coldest month (CMT)). After the regression of the sea during the Burdigalian period, the vegetation developed under the terrestrial conditions, which had started in the Burdigalian time in western and central Anatolia and continued in the early-middle Serravallian period. Warm subtropical climate is suggested during the Chattian and Aquitanian period in western Anatolia and becomes cooler in subtropical conditions because of decreasing of the P/A-ratio during the latest Burdigalian-Langhian. The climate was subtropical in western and central Anatolia during the Early-Late Serravalian due to the increasing of the subtropical elements (17.2 to 20.8°C of MAT and 9.6 to13.1°C of CMT). Besides, decreasing of the CMT and MAT values in western and central Anatolia supports the latest Chattian-earliest Aquitanian warming and middle Miocene climatic optimum that is also globally observed. Warm temperate climatic conditions are observed in the Late Miocene. During the early-middle Tortonian, the values are 15.6 to 20.8°C for the MAT, 5.5 to 13.3°C for the CMT and 823 and 1520 mm for the mean annual precipitation (MAP). They had also dry seasons due to lower boundary of MAP lying at 823mm during the middle-Late Tortonian. The palaeotopography of central Anatolia was higher when compared to that of western Anatolia because dominance of the mountain forests was present during the Middle-Late Miocene in central Anatolia. This study provides the first quantitative model for Late Oligocene-Miocene palaeoclimatic evolution in western and central Anatolia.