HR: 09:45h
AN: PP31A-08    [PDF]
TI: Arctic/North Atlantic Oscillation impact on sea-surface temperature trends during the Holocene: alkenone thermometry, instrumental data and coupled atmosphere-ocean climate simulations
AU: * Kim, J
EM: jungkim@allgeo.uni-bremen.de
AF: University Bremen, FB5 Geowissenschaften, Klagenfurterstraáe, Bremen, 28359 Germany
AU: Lorenz, S J
EM: lorenz@dkrz.de
AF: Max-Planck-Institute for Meteorology, Model and data group, Bundesstrasse 55, Bremen, 20146 Germany
AU: Rimbu, N
EM: nrim@geo.palmod.uni-bremen.de
AF: University Bremen, FB5 Geowissenschaften, Klagenfurterstraáe, Bremen, 28359 Germany
AU: Lohmann, G
EM: gerrit@palmod.uni-bremen
AF: University Bremen, FB5 Geowissenschaften, Klagenfurterstraáe, Bremen, 28359 Germany
AU: Schneider, R R
EM: r.schneider@epoc.u-bordeaux1.fr
AF: Universit‚ de Bordeaux I, D‚partement de G‚ologie et Oc‚anographie, Talence Cedex, 33405 France
AB: To better assess anthropogenic impact on post-industrial climate, it is essential to reconstruct reliable surface temperature distribution patterns in a long-term perspective. Here we show a global spatial pattern of long-term sea-surface temperature (SST) trends over the last 7,000 years solely based on alkenone-derived SST records and coupled atmosphere-ocean transient climate simulations. Our modelling strategy uses a technique for transient simulations with a state-of-the-art general circulation model, where we accelerate the very slow time scale of the Earth's orbital parameters to enable simulations of the whole Holocene. Reconstructed alkenone SST records in the North Atlantic realm show that a continuous SST decrease in the Northeast Atlantic over the last 7,000 years was accompanied by a persistent warming over the western subtropical Atlantic, the eastern Mediterranean Sea, and the northern Red Sea. Our transient ensemble simulations over the last 7,000 years show similar spatial distribution pattern. Based on the analysis of the instrumental data and of model experiments, we show that SSTs during the Holocene can be attributed to a continuous weakening of a Northern Hemisphere atmospheric circulation pattern similar to that of the Arctic/North Atlantic Oscillation (AO/NAO) at present. This implies that the AO/NAO plays not only an important role for short-term climate changes for the present but also for long-term climate trends during the Holocene.
DE: 1600 GLOBAL CHANGE (New category)
DE: 1620 Climate dynamics (3309)
DE: 3339 Ocean/atmosphere interactions (0312, 4504)
DE: 3344 Paleoclimatology
DE: 4267 Paleoceanography
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting