Spatial patterns and driving mechanisms of mid‐Holocene hydroclimate in western North America

Hermann, Nicholas Wayne; Oster, Jessica L.; Ibarra, Daniel E.

doi:10.1002/jqs.3023

“…The small number of Holocene speleothem records from western North America may reflect widespread aridity during the early and middle Holocene, e.g., [127]. The Holocene LC-1 record shows an increase in δ 18 O spel beginning in the early Holocene, a peak in δ 18 O values around 8.0 ka, and a decrease to the present.…”

Section: Last 2000 Yearsmentioning

confidence: 99%

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

Oster

¹

,

Warken

²

,

Sekhon

³

et al. 2019

View full text Add to dashboard Cite

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...

show abstract

“…The small number of Holocene speleothem records from western North America may reflect widespread aridity during the early and middle Holocene, e.g. [135]. The Holocene LC-1 record shows an increase in δ 18 Ospel beginning in the early Holocene, a peak in δ 18 O values around 8.0 ka, and a decrease to the present.…”

Section: Early and Middle Holocenementioning

confidence: 99%

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

Oster¹,

Warken²,

Sekhon³

et al. 2019

Preprint

View full text Add to dashboard Cite

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.

show abstract

“…This shift agrees with shifts in aridity reported in the Pacific Northwest during the mid‐Holocene elsewhere inside and out of the basin (e.g. Wigand, , ; Thompson et al ., ; Dugas, ; Pinson, ; Hermann et al ., ), and provides a Pleistocene–Holocene environmental context along the western boundary of the Harney Basin that has been missing (Table ).…”

Section: Results and Interpretationmentioning

confidence: 99%

Characterizing formation processes of Rimrock Lake, a Late Pleistocene–Holocene playa, Harney Basin, south‐eastern Oregon, USA, using an end‐member mixing analysis

Collins

¹

,

Gill

²

,

Langford

³

2018

J Quaternary Science

3

0

View full text Add to dashboard Cite

Playas collect sediments from different transported processes, producing grain-size distributions (GSDs) reflecting changes in environment. End-member mixing analysis (EMMA) was used to derive end-members (EMs) from 256 sediment samples from Rimrock Lake (Harney Basin, Oregon, USA) and a nearby relict channel. EMMA identified six EMs representing deposition in fluvial, lacustrine, littoral and colluvial environments. Stratigraphy was time-correlated using nine radiocarbon dates. Results show that Rimrock Lake existed by $ 18 535 cal a BP. A relict playa surface also was exposed along its margin and indicates lake contraction $ 6190-5990 cal a BP. In the relict channel, a dominant eolian environment is identified at $ 8000 cal a BP. These results represent a shift to a more arid environment in the Harney Basin beginning around the mid-Holocene and are in general agreement with other studies reported in the Great Basin. This study demonstrates the application of EMMA for analyzing complex playa sediments and for linking environmental response across separate but related geomorphic environments. Our results provide a paleoenvironmental record along Harney Basin's western margin between $ 18 500 and 6000 cal a BP and demonstrate the use of small playas in the basin as environmental archives. Figure 2. (A) Modified Google Earth image of Rimrock Lake with geomorphic features, core locations and Trench 1 identified. (B) Modified Google Earth image of Rimrock Draw Rockshelter with excavation units, Trench 2 and channel boundary identified (dashed line).

show abstract

Spatial patterns and driving mechanisms of mid‐Holocene hydroclimate in western North America

Cited by 28 publications

References 56 publications

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

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

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

Characterizing formation processes of Rimrock Lake, a Late Pleistocene–Holocene playa, Harney Basin, south‐eastern Oregon, USA, using an end‐member mixing analysis

Contact Info

Product

Resources

About