Past Interglacial Temperature Regimes (PAINTER): Marine isotope stages 11 in the NE-Atlantic sector
Zusammenfassung der Projektergebnisse
Temporal and spatial SST patterns were reconstructed for MIS 11c and MIS 5e using five sediment cores from the eastern North Atlantic that described a submeridional transect from polar to subtropical latitudes. Additionally, humidity conditions in the West Africa and Mediterranean region were investigated for MIS 11c. As MIS 11c and MIS 5e are often used to test various aspects of climate change, the goal of the project was to investigate the spatial differences in ocean-atmosphere interaction during these periods and to compare them to the present day/Holocene situation. Main emphasis was placed on identifiying certain operational patterns and how they relate to processes of the North Atlantic Oscillations (NAO). Our foraminiferal- and alkenone-based SST reconstructions were supported by planktic and benthic stable isotope measurements, foraminiferal analyses down to species level, content of ice rafted debris (IRD) in middle and high latitudes, and iron concentrations as a proxy of aeolian dust input off NW Africa. When compared to the Holocene, our results from MIS 11c revealed the coexistence of a cold SST anomaly and an extended sea-ice cover in the Nordic seas with a warm SST anomaly off West Africa and in the western Mediterranean Sea implying high meridional SST gradients over the eastern North Atlantic. Additionally, it was found that humid conditions in West Africa during MIS 11c lasted considerably longer than during the Holocene. Such a situation is characteristic for a prevalence of a negative NAO index when comparatively low atmospheric pressure gradients direct the main storm track over the North Atlantic towards the Mediterranean Sea resulting in enhanced humidity over the Mediterranean region and a reduction of warm surface water flow into the Nordic seas. For 5e our SST reconstructions also indicate a warm anomaly in the low latitudes. However, in the Nordic seas the SST results are controversial. Alkenone SST estimates imply existence of a cold anomaly over MIS 5e interglaciation, whereas, warmest foraminiferal SST values during MIS 5e are close to the modern (or late Holocene) ones or even slightly higher. Therefore, additional analyses are needed to draw a conclusion about the prevailing NAO mode for MIS 5e. The higher-than-Holocene SSTs found in the middle latitudes for MIS 11 and 5e are corroborated by comparatively high relative abundances of rare thermophilic species. We consider this as evidence of an intensification of the subpolar gyre in the North Atlantic.
Projektbezogene Publikationen (Auswahl)
-
(2008). Late Holocene water mass change in the Norwegian Sea caused by different ocean-atmosphere circulation patterns In: AGU Fall Meeting, 15.12.-19.12, San Francisco, California, USA
Bauch, H. und Kandiano, E.
-
(2008). Marine temperature records from MIS 11 reveal strong climate linkages between the low and middle northern latitudes In: EPICA 2008, 10.11.-13.11, Venice, Italy
Kandiano, E., Bauch, H., Fahl, K., Helmke, J. und Röhl, U.
-
(2008). Uniform climate development between the subtropical and subpolar Northeast Atlantic across marine isotope stage 11. Climate of the Past 4, 433-457
Helmke, J. P., Bauch, H. A., Röhl, U., and Kandiano, E. S.
-
(2008). Uniform climate development between the subtropical and subpolar Northeast Atlantic across marine isotope stage [Poster] In: EGU General Assembly, 14.04.-18.04, San Francisco, California, USA
Helmke, J., Bauch, H., Röhl, U. und Kandiano, E.
-
(2009). Are MIS 11 and the Holocene really analogous? In: The XVIII International Conference on Marine Geology, 16.11.-20.11, Moscow, Russia
Kandiano, E., Bauch, H., Fahl, K., Helmke, J. P. und Röhl, U.
-
(2009). Atmospheric controls on Holocene water mass and sea-ice drift patterns in the Subarctic Nordic seas In: 3. APEX Workshop, 31.03.-03.04, Copenhagen, Denmark
Bauch, H. und Kandiano, E.
-
(2009). SST-pattern in the North Atlantic reveals pronounced differences during MIS 11 and the Holocene] In: AGU Fall Meeting, 14.12.-18.12, San Francisco, California, USA
Kandiano, E., Bauch, H., Fahl, K., Helmke, J. P. und Röhl, U.
-
(2010). Persistent seesaw SST-patterns between the Nordic seas and the adjacent North Atlantic during pronounced interglaciations In: FORAMS 2010 - International Symposium on Foraminifera, 05.09.-10.09.2010, Bonn
Kandiano, E., Bauch, H., Fahl, K. und Helmke, J. P.
-
(2010). The Eemian Climate Controversy in the Polar North In: AGU Fall Meeting 2010, 16.12.2010, San Francisco, USA
Bauch, H. A., Kandiano, E. und Van Nieuwenhove, N.
-
(2011) Climatic Bisection of the last Interglacial Warm Period in the Polar North Atlantic. Quaternary Science Reviews
Bauch, H.A., Kandiano, E.S., Helmke J.P., Andersen, N., Rosell-Mele, A., Erlenkeuser, H.
-
(2011). Variations in the Polar-Directed Oceanic Heat During Past Interglacials: Causes and Consequences. In: XVIII INQUA Congress, 21-27.07 Bern, Switzerland
Bauch, H. A., Kandiano, E. S.
-
(2011.) Intensification Changes of the Interglacial Subpolar Gyre System in the North Atlantic Region. In: XVIII INQUA Congress, 21-27.07 Bern, Switzerland
Kandiano, E., Bauch, H., Fahl, K., Helmke, J. P.
