Speleothem Paleoclimatology for the Caribbean, Central America, and North America

Abstract

Speleothem oxygen isotope records from the Caribbean, Central, and North America reveal climatic controls that include orbital variation, deglacial forcing related to ocean circulation and ice sheet retreat, and the influence of local and remote sea surface temperature variations. Here, we review these records and the global climate teleconnections they suggest following the recent publication of the Speleothem Isotopes Synthesis and Analysis (SISAL) database. We find that low-latitude records generally reflect changes in precipitation, whereas higher latitude records are sensitive to temperature and moisture source variability. Tropical records suggest precipitation variability is forced by orbital precession and North Atlantic Ocean circulation driven changes in atmospheric convection on long timescales, and tropical sea surface temperature variations on short timescales. On millennial timescales, precipitation seasonality in southwestern North America is related to North Atlantic climate variability. Great Basin speleothem records are closely linked with changes in Northern Hemisphere summer insolation. Although speleothems have revealed these critical global climate teleconnections, the paucity of continuous records precludes our ability to investigate climate drivers from the whole of Central and North America for the Pleistocene through modern. This underscores the need to improve spatial and temporal coverage of speleothem records across this climatically variable region.Quaternary 2019, 2, 5 2 of 33 original authors. The challenges found while compiling such data are discussed in [1]. The database archives speleothem oxygen and carbon isotope data, detailed chronologic and analytical information, and important metadata for each cave site and speleothem such as bedrock geology, overburden thickness, and whether cave monitoring was conducted, among other pieces of information that are essential for working with and interpreting speleothem isotope records.Of the 376 records included in SISAL_v1, 42 are from cave sites in Central and North America and the Caribbean [2]. These records cover a vast region, spanning the tropics to mid-latitudes and bordering two oceans, with climate controls that are highly variable both in the modern and through time. Speleothem records from this region have revealed critical climate teleconnections between the polar regions, the tropics, and the mid-latitudes at decadal to orbital timescales [3][4][5][6]. These records have provided evidence for the effects of climate variability on ancient civilizations [7-9], and contributed toward open questions and key debates regarding Earth's climate system [3,10]. Here, we discuss the spatial and temporal coverage of North and Central American and Caribbean speleothem records included in SISAL_v1 and the predominant controls on δ 18 O spel variability in each region. We review the most salient discoveries arising from regional records included in SISAL_v1 and conduct a statistical analysis to underscore observed spatial relationships. O...

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

“…Similarly, the δ 18 O values of PR-LA-1 show decreasing amplitudes of centennial to millennial oscillations after 30 ka compared to NGRIP and Cariaco with weak or even absent excursions across GIs 2-5 ( Figure 6). This suggests a progressive weakening of the connection between Caribbean precipitation and North Atlantic forcing as previously suggested by other studies (Oster et al, 2019;Warken et al, 2019), highlighting the complex climatological patterns in this region and arguing for regionally diverse expansions/contractions of the zonal mean of the ITCZ combined with meridional shifts.…”

“…In particular, the details of the spatio-temporal structure and evolution of the Atlantic ITCZ are still not well understood (Warken et al, 2019). Mounting evidence from both modeling studies and proxy records suggests that the simple explanation of a north-south shifting of the ITCZ is not adequate to explain the observed rainfall patterns, especially because the most northern shifts of the Atlantic ITCZ are linked to a complex set of forcings and feedbacks on different timescales (Asmerom et al, 2020;Oster et al, 2019;Roberts & Hopcroft, 2020;Singarayer et al, 2017). For instance, the magnitude and extent of the ITCZ's latitudinal movements, and the role of external forcing, such as insolation, in modulating this variability especially during pronounced and/or abrupt climate change events during glacial periods, such as Heinrich and D/O events, remain unclear.…”

SISAL: Bringing Added Value to Speleothem Research

“…[44], this issue). For example, although there is an uneven spatio-temporal coverage of speleothem records in North Central America ( [45], this issue), the observed more negative and variable δ 18 O at high latitudes during the LGM is consistent with studies that suggest a more variable temperature during this period at higher latitudes [46].…”

SISALv2: A comprehensive speleothem isotope database with multiple age-depth models

“…CC BY 4.0 License. Burstyn et al, 2019;Deininger et al, 2019;Kaushal et al, 2018;Lechleitner et al, 2018;Oster et al, 2019;Zhang et al, 2019). The potential for using the SISAL database to evaluate climate models was explored using an updated version of the database (SISALv1b; Atsawawaranunt et al, 2019) that contains 455 speleothem records from 211 sites .…”

“…Analyses of the data included in SISALv1 (Braun et al, 2019a;Burstyn et al, 2019;Deininger et al, 2019;Kaushal et al, 2018;Kern et al, 2019;Lechleitner et al, 2018;Oster et al, 2019;Zhang et al, 2019) and SISALv1b (Comas-Bru et al, 2019) revealed a number of errors in specific records that have now been corrected. These revisions include, for example, updates in mineralogies (sample.mineralogy), revised coordinates (site.latitude and/or site.longitude) and addition of missing information that was previously entered as "unknown".…”