Persistent link between Caribbean precipitation and Atlantic Ocean
circulation during the Last Glacial revealed by a speleothem record from
Puerto Rico
Abstract
The high sensitivity of tropical hydro-climate to the mean position of
the intertropical convergence zone (ITCZ) at different time scales is
well known. However, recent research suggests a more complex behaviour
of the northern hemispheric tropical rain belts in the western tropical
Atlantic. Here we present a precisely dated speleothem multi-proxy
record from a well-monitored cave from Puerto Rico, covering the period
between 46.2 and 15.4 ka BP in unprecedented resolution. This allows the
investigation of multi-decadal to millennial-scale climate variability.
The proxy records document a pronounced response of regional rainfall to
abrupt centennial to millennial-scale climatic excursions in the North
Atlantic across the Last Glacial (i.e., Heinrich Stadials and
Dansgaard/Oeschger events). In particular, we observe a strong agreement
between the speleothem proxy data and the strength of the Atlantic
meridional overturning circulation, supporting a persistent link of
regional precipitation to oceanic forcing. Spectral analysis suggests
that multi-decadal to centennial variability persisted in the regional
hydro-climate not only during stadial and interstadial conditions, but
also during the Last Glacial Maximum, supporting the hypothesis that the
Atlantic low-latitude regions respond to internal modes of climate
variability on these time scales regardless of the global climate state.
The compilation with other paleo-precipitation records enables the
reconstruction of past changes in position, strength and extent of the
ITCZ in the western tropical Atlantic in response to millennial and
orbital global climate change.