Publication Date:
2019-07-17
Description:
Proxy reconstructions of tropical Atlantic sea surface temperature (SST) that extend beyond the period of
instrumental observations have primarily focused on centennial to millennial variability rather than on seasonal
to multidecadal variability. Here we present monthly-resolved records of Sr/Ca (a proxy of SST) from
fossil annually-banded Diploria strigosa corals from Bonaire (southern Caribbean Sea). The individual corals
provide time-windows of up to 68 years length, and the total number of 295 years of record allows for
assessing the natural range of seasonal to multidecadal SST variability in the western tropical Atlantic during
snapshots of the mid- to late Holocene. Comparable to modern climate, the coral Sr/Ca records reveal
that mid- to late Holocene SST was characterised by clear seasonal cycles, persistent quasi-biennial and
prominent interannual as well as inter- to multidecadal-scale variability. However, the magnitude of SST
variations on these timescales has varied over the last 6.2 ka. The coral records show increased seasonality
during the mid-Holocene consistent with climatemodel simulations indicating that southern Caribbean SST
seasonality is induced by insolation changes on orbital timescales,whereas internal dynamics of the climate
system play an important role on shorter timescales. Interannual SST variability is linked to ocean–
atmosphere interactions of Atlantic and Pacific origin. Pronounced interannual variability in the western
tropical Atlantic is indicated by a 2.35 ka coral, possibly related to a strengthening of the variability of the
El Niño/Southern Oscillation throughout the Holocene. Prominent inter- to multidecadal SST variability is
evident in the coral records and slightly more pronounced in the mid-Holocene. We finally argue that our
coral data provide a target for studying Holocene climate variability on seasonal and interannual to multidecadal
timescales, when using further numerical models and high-resolution proxy data.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
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isiRev