Persistent Link Between Caribbean Precipitation and Atlantic Ocean Circulation During the Last Glacial Revealed by a Speleothem Record From Puerto Rico

Sophie F Warken,Andrea Schröder‐Ritzrau,Denis Scholz,Amos Winter,Christoph Spötl,Rolf Vieten,Thomas E Miller,Augusto Mangini,Klaus P Jochum

doi:10.1029/2020pa003944

Abstract

AbstractThe sensitivity of tropical Atlantic precipitation patterns to the mean position of the Intertropical Convergence Zone (ITCZ) at different time scales is well‐known. However, recent research suggests a more complex behavior of the northern hemispheric tropical rain belt related to the ITCZ in the western tropical Atlantic. Here we present a precisely dated speleothem multi‐proxy record from a well‐monitored cave in Puerto Rico, covering the period between 46.2 and 15.3 ka. The stable isotope and trace element records document a pronounced response of regional rainfall to abrupt climatic excursions in the North Atlantic across the Last Glacial such as Heinrich stadials and Dansgaard/Oeschger events. The annual to multidecadal resolution of the proxy time series allows substructural investigations of the recorded events. Spectral analysis suggests that multidecadal to centennial variability persisted in the regional hydroclimate mainly during interstadial conditions but also during the Last Glacial Maximum. 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 oceanic forcing to regional precipitation. Comparison to 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‐scale global climate change.

Highlights

Last Glacial precipitation reconstructions from the tropical Atlantic region have documented pronounced rainfall variability on centennial to orbital timescales (Deplazes et al, 2013; Hodell et al, 2008; Peterson et al, 2000)
We observe a strong agreement between the speleothem proxy data and the strength of the Atlantic meridional overturning circulation, supporting a persistent link of oceanic forcing to regional precipitation
In the case of the prominent Heinrich events, the latitudinal displacements of the Intertropical Convergence Zone (ITCZ) resulted from a weakening of the Atlantic Meridional Overturning Circulation (AMOC) (Henry et al, 2016; Lynch‐Stieglitz et al, 2014; McManus et al, 2004)

Summary

Introduction

Last Glacial precipitation reconstructions from the tropical Atlantic region have documented pronounced rainfall variability on centennial to orbital timescales (Deplazes et al, 2013; Hodell et al, 2008; Peterson et al, 2000). These observations are interpreted to reflect a variable position of the Intertropical Convergence Zone (ITCZ) in response to changes in cross‐equatorial temperature gradients The influence of ocean circulation on changes in Last Glacial tropical rainfall, for example, associated with D/O events, is still under debate (Burckel et al, 2015; Henry et al, 2016; Roberts & Hopcroft, 2020; Them Il et al, 2015; Waelbroeck et al, 2018)

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