FN Archimer Export Format
PT J
TI Internal ice-sheet variability as source for the multi-century and millennial-scale iceberg events during the Holocene? A model study
BT 
AF BUGELMAYER-BLASCHEK, Marianne
   ROCHE, Didier M.
   RENSSEN, Hans
   ANDREWS, John T.
AS 1:1;2:1,2;3:1;4:3,4;
FF 1:;2:;3:;4:;
C1 Vrije Univ Amsterdam, Fac Earth & Life Sci, Earth & Climate Cluster, Amsterdam, Netherlands.
   Univ Paris Saclay, CEA CNRS UVSQ, LSCE IPSL, Lab Sci Climat & Environm, F-91191 Gif Sur Yvette, France.
   Univ Colorado, INSTAAR, Boulder, CO 80309 USA.
   Univ Colorado, Dept Geol Sci, Boulder, CO 80309 USA.
C2 UNIV VRIJE AMSTERDAM, NETHERLANDS
   UNIV PARIS SACLAY, FRANCE
   UNIV COLORADO, USA
   UNIV COLORADO, USA
IF 4.797
TC 5
UR https://archimer.ifremer.fr/doc/00421/53253/54711.pdf
   https://archimer.ifremer.fr/doc/00421/53253/54729.zip
LA English
DT Article
CR IMAGES V LEG 1-MD114
   IMAGES V LEG 4-MD114
BO Marion Dufresne
DE ;Greenland ice sheet;Holocene;Bond events;Icebergs;Climate modeling
AB The climate of the Holocene, the current interglacial covering the past 11,700 years, has been relatively stable compared to previous periods. Nevertheless, repeating occurrence of rapid natural climate changes that challenged human society are seen in proxy reconstructions. Ocean sediment cores for example display prominent peaks of enhanced ice rafted debris (IRD) during the Holocene with a multidecadal to millennial scale periodicity. Different mechanisms were proposed that caused these enhanced IRD events, for example variations in the incoming total solar irradiance (TSI), volcanic eruptions and the combination of internal climate variability and external forcings. We investigate the probable mechanisms causing the occurrence of IRD-events over the past 6000 years using a fully coupled climate- ice sheet - iceberg model (iLOVECLIM). We performed 19 experiments that differ in the applied forcings (TSI, volcanic) and the initial atmospheric conditions. To explore internal ice sheet variability one further experiment was done with fixed climate conditions. All the model runs displayed prominent peaks of enhanced iceberg melt flux (IMF), independent of the chosen experimental set-up. The spectral analysis of the experiments with the ice-sheet- climate model coupled displays significant peaks at 2000, 1000 years in all the experiments and at 500 years in most runs. The experiment with fixed climate conditions displays one significant peak of about 1500 years related to internal ice sheet variability. This frequency is modulated to 2000 and 1000 years in all the experiments with a coupled climate- ice sheet due to interactions between the climate components. We further investigate the impact of minimum TSI events on the timing and occurrence of enhanced IMF. In the experimental set-up that was forced with idealized sinusoidal TSI variations (+/- 4 Wm(-2)), we find a significant occurrence of an increased iceberg melt flux about 60 years after the minimum TSI value. Yet, we also see a significant time lag of 80 years between reconstructed TSI minima and the simulated enhanced iceberg melt flux in some of the experiments without TSI forcing. The fact that also model runs that are not forced with TSI variations display an 80 year time lag indicates that the relationship between TSI and IMF is due to internal dynamics of the coupled system. From our experiments we conclude that internal ice sheet variability seems to be the source of the multi-century and millennial-scale iceberg events during the Holocene. 
PY 2016
PD APR
SO Quaternary Science Reviews
SN 0277-3791
PU Pergamon-elsevier Science Ltd
VL 138
UT 000374369700010
BP 119
EP 130
DI 10.1016/j.quascirev.2016.01.026
ID 53253
ER

EF