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(Fensterer et al.
2010
,
2012
,
2013
). Dating uncertainties are between 0.01 and 0.1
thousand years (ka), but are larger (up to 0.8 ka) for a few samples that contain
relatively large amounts of detrital Th. Stalagmites were microsampled at a reso-
lution of approximately 2, 4
13
C. The
stalagmites grew continuously during the last 1.3 ka and almost continuously during
the last 12.5 ka. Stalagmite
18
O and
-
10, and 15 years, and analyzed for
δ
δ
18
O on seasonal to interannual timescales mainly
δ
18
O of precipitation, which in turn is mainly controlled by the amount
effect (Fensterer et al.
2012
,
2013
).
Several numerical experiments were performed for three periods of the Holocene
using the Earth system model COSMOS (Wei et al.
2012
): Pre-industrial [0 ka
before present (BP)], mid-Holocene (6 ka BP) and early Holocene (9 ka BP).
Con
re
ects the
δ
gurations with different boundary conditions, i.e., orbital parameters, green-
house gas concentration, land-sea distribution and freshwater
flux from melting of
the Laurentide ice sheet (Wei and Lohmann
2012
; Wei et al.
2012
), allowed to
investigate their in
uence on the climate variability of the Caribbean region during
the Holocene on seasonal and interannual to millennial timescales.
3 Key Findings
18
O records indicate
that mid- to late Holocene SST and SSS were characterized by persistent quasi-
biennial and prominent interannual to multidecadal variability (Fig.
1
) (Giry et al.
2012
,
2013
). The amplitudes of SST and SSS variations on these timescales have
varied since the mid-Holocene. On these timescales, warmer conditions were
accompanied by more saline conditions at the sea surface, and vice versa. Potential
forcing mechanisms include the wind-induced advection of surface waters from the
south and variations in the strength of the Atlantic Meridional Overturning Cir-
culation (AMOC) (Giry et al.
2013
). SST variability on inter- to multidecadal
timescales was more pronounced during the mid-Holocene compared to the late
Holocene and accompanied by enhanced SSS variability (Giry et al.
2012
,
2013
), a
In the southern Caribbean, monthly resolved coral Sr/Ca and
δ
finding that was not detected in the COSMOS simulations. An increased amplitude
of the SSS annual cycle and a slightly increased amplitude of the SST annual cycle
were reconstructed for the mid-Holocene, which are consistent with the COSMOS
simulations (Giry et al.
2012
,
2013
). These reconstructed changes are mainly
attributed to orbitally induced insolation changes that also favor a northward shift of
the Intertropical Convergence Zone (ITCZ), resulting in more precipitation in the
Caribbean (Fig.
2
), especially during summer. Anomalous sea-surface conditions
occurred around 2.35 ka BP, characterized by enhanced interannual SST variability
at typical El Ni
ñ
o-Southern Oscillation (ENSO) periods, increased amplitude of the
SST annual cycle, and a reversal of the SSS annual cycle (Giry et al.
2012
,
2013
).
Such anomalous time intervals were not detected in the COSMOS simulations,
which rather suggest a quasi-persistent ENSO in
uence on the Caribbean during the
Holocene (Wei and Lohmann
2013
).
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