Control of Seasonality and Interannual to Centennial Climate Variability in the Caribbean During the Holocene—Combining Coral Records, Stalagmite Records and Climate Models - Integrated Analysis of Interglacial Climate Dynamics (INTERDYNAMIC) - page 67

(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 ).