DO CENTENNIAL-SCALE HYDROLOGICAL CHANGES RECORDED IN THE BLACK SEA AND NORTHERN RED SEA DURING THE HOLOCENE REFLECT LONG-TERM CHANGES IN THE NORTH ATLANTIC/ARCTIC OSCILLATION?

The most prominent mode of Northern Hemisphere interannual to decadal climate variability is the North Atlantic Oscillation/Arctic Oscillation (NAO/AO). There is however little known about longer-term variations of this atmospheric circulation pattern during the Holocene. Proxy data for past surface ocean properties and continental rainfall based on two high resolution sediment cores from the south-western Black Sea and the northernmost Gulf of Aqaba were used to infer hydrological changes in northern Anatolia and the northern Red Sea region during the last 7500 years. Spatial correlations of the NAO/AO index with instrumental records of precipitation demonstrate that NAO/AO presently affects these regions in an opposite manner. In the south-western Black Sea sediments are generally warved, with frequent intercalations of homogeneous clay layers which are interpreted as suspension fallout events from the Sakarya river plume related to increased winter-rain in western Anatolia. The frequency of these layers shows distinct variations on centennial time-scales, which imply long-term changes in Anatolian rainfall throughout the last ca. 7500 years. In the northernmost Gulf of Aqaba, Holocene aridity variations are documented by distinct changes in the eolian dust content. Multi-species stable oxygen isotope data indicate concomitant variations in the local hydrography. The opposite pattern found in instrumental data is also clearly present on centennial time-scales. Consistent with a “NAO/AO-like” pattern, the records from the Black Sea and northern Red Sea additionally correspond to surface ocean changes in the northern North Atlantic. This correspondence suggests a broad teleconnective response to Holocene variations in the NAO/AO anomaly, linking colder ice-bearing surface waters in high northern North Atlantic latitudes with less arid conditions in the northernmost Red Sea area and reduced precipitation in western Anatolia, possibly controlled by solar variability.