A coupled climate model simulation of Marine Isotope Stage 3 stadial climate

Type Article
Date 2011
Language English
Author(s) Brandefelt J.1, Kjellstrom E.2, Naslund J. -O.3, Strandberg G.2, Voelker A. H. L.4, Wohlfarth B.5
Affiliation(s) 1 : KTH, Dept Mech, Linne Flow Ctr, S-10044 Stockholm, Sweden.
2 : Swedish Meteorol & Hydrol Inst, S-60176 Norrkoping, Sweden.
3 : Swedish Nucl Fuel & Waste Management Co SKB, S-10240 Stockholm, Sweden.
4 : Unidade Geol Marinha, LNEG, P-2610143 Zambujal, Amadora, Portugal.
5 : Stockholm Univ, Dept Geol Sci, S-10961 Stockholm, Sweden.
Source Climate Of The Past (1814-9324) (Copernicus Gesellschaft Mbh), 2011 , Vol. 7 , N. 2 , P. 649-670
DOI 10.5194/cp-7-649-2011
WOS© Times Cited 16
Abstract We present a coupled global climate model (CGCM) simulation, integrated for 1500 yr to quasi-equilibrium, of a stadial (cold period) within Marine Isotope Stage 3 (MIS 3). The simulated Greenland stadial 12 (GS12; similar to 44 ka BP) annual global mean surface temperature (T-s) is 5.5 degrees C lower than in the simulated recent past (RP) climate and 1.3 degrees C higher than in the simulated Last Glacial Maximum (LGM; 21 ka BP) climate. The simulated GS12 is evaluated against proxy data and previous modelling studies of MIS3 stadial climate. We show that the simulated MIS 3 climate, and hence conclusions drawn regarding the dynamics of this climate, is highly model-dependent. The main findings are: (i) Proxy sea surface temperatures (SSTs) are higher than simulated SSTs in the central North Atlantic, in contrast to earlier simulations of MIS 3 stadial climate in which proxy SSTs were found to be lower than simulated SST. (ii) The Atlantic Meridional Overturning Circulation (AMOC) slows down by 50% in the GS12 climate as compared to the RP climate. This slowdown is attained without freshwater forcing in the North Atlantic region, a method used in other studies to force an AMOC shutdown. (iii) El-Nino-Southern Oscillation (ENSO) teleconnections in mean sea level pressure (MSLP) are significantly modified by GS12 and LGM forcing and boundary conditions. (iv) Both the mean state and variability of the simulated GS12 is dependent on the equilibration. The annual global mean T-s only changes by 0.10 degrees C from model years 500-599 to the last century of the simulation, indicating that the climate system may be close to equilibrium already after 500 yr of integration. However, significant regional differences between the last century of the simulation and model years 500-599 exist. Further, the difference between simulated and proxy SST is reduced from model years 500-599 to the last century of the simulation. The results of the ENSO variability analysis is also shown to depend on the equilibration.
Full Text
File Pages Size Access
Publisher's official version 22 1 MB Open access
Top of the page