Supplementary material to "Last glacial millennial-scale hydro-climate and temperature changes in Puerto Rico constrained by speleothem fluid inclusion δ18O and δ2H values"

Abstract. We present speleothem fluid inclusion δ18Of and δ2Hf values from Larga Cave, Puerto Rico, that covers the interval between 46.2 to 15.3 ka before present on millennial scale, including the Last Glacial Maximum (LGM) and several stadial and interstadial cycles. The dataset can be divided in two main clusters of stable isotope compositions of the fluid inclusion water with respect to the global meteoric water line which coincide with strong variations in the water content of the stalagmite. In particular, this clustering is found to be climate related, where the first cluster comprises samples from cold and dry periods, such as Heinrich and Greenland stadials, as well as parts of the LGM, which exhibit very high δ18Of and δ2Hf values. We interpret this enrichment as caused by evaporation inside the cave due to enhanced cave ventilation during these colder and drier times. In contrast, in most samples corresponding to warmer and wetter Greenland interstadials, but also for some from Heinrich Stadial 2 and 3, the δ18Of and δ2Hf values plot on the meteoric water line and modification of fluid inclusion water due to “in-cave” evaporation is found negligible. Consequently, variations of last glacial hydro-climate and temperature in the western tropical Atlantic can be constrained. In general, δ18Of values from fluid inclusions are up to 3 ‰ higher than those of modern drip water, which is interpreted as a weaker atmospheric convective activity during the last glacial period. In addition, reconstructed temperatures suggest an average cooling of c. 3 °C during the LGM compared to modern cave temperature. During Heinrich Stadials 2 and 3, reconstructed cave temperatures yield an additional cooling of 2.9 ± 2.6 °C and 4.4 ± 0.6 °C, respectively. Higher δ18Of values of these samples further suggest that the drip water was dominated by orographic rainfall and/or cold fronts, along with weak or even absent convective activity. In contrast, during interstadial phases, reconstructed temperatures reached nearly modern values, and convective activity was comparable or only slightly weaker than today.

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Environmental variability in response to abrupt climatic change during the Last Glacial–Interglacial Transition (16–8 cal ka BP): evidence from Mainland, Orkney

Scottish Journal of Geology ◽

10.1144/sjg2019-006 ◽

2019 ◽

Vol 56 (1) ◽

pp. 30-46 ◽

Cited By ~ 2

Author(s):

Ashley M. Abrook ◽

Ian P. Matthews ◽

Alice M. Milner ◽

Ian Candy ◽

Adrian P. Palmer ◽

...

Keyword(s):

Early Career ◽

Early Holocene ◽

Content Type ◽

Last Glacial ◽

Principal Curve ◽

Link Type ◽

Supplementary Material ◽

Career Research ◽

The Last Glacial ◽

Millennial Scale

The Last Glacial–Interglacial Transition (LGIT) is a period of climatic complexity where millennial-scale climatic reorganization led to changes in ecosystems. Alongside millennial-scale changes, centennial-scale climatic events have been observed within records from Greenland and continental Europe. The effects of these abrupt events on landscapes and environments are difficult to discern at present. This, in part, relates to low temporal resolutions attained by many studies and the sensitivity of palaeoenvironmental proxies to abrupt change. We present a high-resolution palynological and charcoal study of Quoyloo Meadow, Orkney and use the Principal Curve statistical method to assist in revealing biostratigraphic change. The LGIT vegetation succession on Orkney is presented as open grassland and Empetrum heath during the Windermere Interstadial and early Holocene, and open grassland with Artemisia during the Loch Lomond Stadial. However, a further three phases of ecological change, characterized by expansions of open ground flora, are dated to 14.05–13.63, 10.94–10.8 and 10.2 cal ka BP. The timing of these changes is constrained by cryptotephra of known age. The paper concludes by comparing Quoyloo Meadow with Crudale Meadow, Orkney, and suggests that both Windermere Interstadial records are incomplete and that fire is an important landscape control during the early Holocene.Supplementary material: All raw data associated with this publication: raw pollen counts, charcoal data, Principal Curve and Rate of Change outputs and the age-model output are available at https://doi.org/10.6084/m9.figshare.c.4725269Thematic collection: This article is part of the ‘Early Career Research’ available at: https://www.lyellcollection.org/cc/SJG-early-career-research

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Last Glacial multi-decadal to millennial-scale precipitation variability inferred from Puerto Rican speleothems

10.5194/egusphere-egu2020-19591 ◽

2020 ◽

Author(s):

Sophie Warken ◽

Rolf Vieten ◽

Amos Winter ◽

Christoph Spötl ◽

Thomas Miller ◽

...

Keyword(s):

Puerto Rico ◽

Precipitation Variability ◽

Intertropical Convergence Zone ◽

Convergence Zone ◽

Tropical Atlantic ◽

Last Glacial ◽

Proxy Records ◽

Northern Hemispheric ◽

The Last Glacial ◽

Millennial Scale

The high sensitivity of climate variability to the mean position of the intertropical convergence zone at different time scales is well known. However, due to a lack of absolutely dated high-resolution proxy records, the long-term changes in the tropical Atlantic oceanic and atmospheric circulation system prior to the late Holocene are still not well constrained. Paleo climate reconstructions and model studies suggest a very complex response of the northern hemispheric tropical rain belts in the western tropical Atlantic depending on the nature of the forcing, surface type and surrounding continent-ocean configuration.Here we present a high resolution multi-proxy speleothem record from Cueva Larga (Puerto Rico) covering the last Glacial between 46 and 15 ka BP. Precise 230Th/U-dating reveals growth rates between 50 up to more than 1000 &#181;m/year which allow for the investigation of multi-decadal to millennial scale variability in the stable isotope (&#948;18O and &#948;13C) and elemental records.The analysed proxies document a pronounced response of regional precipitation to abrupt centennial to millennial scale climatic excursions across the last Glacial, such as Heinrich Stadials and Dansgaard/Oeschger oscillations. Here, we observe a strong agreement between our paleo-precipitation reconstruction and climate proxy records which are indicative of the strength of the Atlantic meridional overturning circulation and northern hemispheric temperature changes. The coherence of speleothem &#948;18O values with sedimentary 231Pa/230Th also on sub-millennial timescales supports a persistent link of regional precipitation variability to ocean circulation variability. Spectral analysis further suggests that multi-decadal to centennial variability persisted in the western tropical Atlantic 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 of our dataset from Puerto Rico with other paleo-precipitation records allows for the reconstruction of past changes in position, strength and extent of the intertropical convergence zone in the western tropical Atlantic and reveal the existence of spatio-temporal gradients in response to millennial to orbital climate change.

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Supplementary material to "Impact of millennial-scale oceanic variability on the Greenland ice sheet evolution throughout the Last Glacial Period"

10.5194/cp-2018-129-supplement ◽

2018 ◽

Author(s):

Ilaria Tabone ◽

Alexander Robinson ◽

Jorge Alvarez-Solas ◽

Marisa Montoya

Keyword(s):

Ice Sheet ◽

Greenland Ice Sheet ◽

Glacial Period ◽

Last Glacial Period ◽

Last Glacial ◽

Supplementary Material ◽

The Last Glacial ◽

Oceanic Variability ◽

Millennial Scale

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EVIDENCE FOR MILLENNIAL-SCALE CLIMATE VARIABILITY IN THE SURFACE WATERS ABOVE ODP SITE 984, NE ATLANTIC OCEAN DURING THE LAST GLACIAL INTERVAL (MIS 4-2)

10.1130/abs/2018ne-310752 ◽

2018 ◽

Author(s):

Jacob Ross ◽

◽

James L. Cullen

Keyword(s):

Climate Variability ◽

Atlantic Ocean ◽

Surface Waters ◽

Ne Atlantic ◽

Last Glacial ◽

Ne Atlantic Ocean ◽

The Last Glacial ◽

Millennial Scale

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δ13C decreases in the upper western South Atlantic during Heinrich Stadials 3 and 2

Climate of the Past ◽

10.5194/cp-13-345-2017 ◽

2017 ◽

Vol 13 (4) ◽

pp. 345-358 ◽

Cited By ~ 4

Author(s):

Marília C. Campos ◽

Cristiano M. Chiessi ◽

Ines Voigt ◽

Alberto R. Piola ◽

Henning Kuhnert ◽

...

Keyword(s):

Climate Change ◽

South Atlantic ◽

Meridional Overturning Circulation ◽

Glacial Period ◽

Last Deglaciation ◽

Last Glacial Period ◽

Last Glacial ◽

Change Events ◽

The Last Glacial ◽

Millennial Scale

Abstract. Abrupt millennial-scale climate change events of the last deglaciation (i.e. Heinrich Stadial 1 and the Younger Dryas) were accompanied by marked increases in atmospheric CO2 (CO2atm) and decreases in its stable carbon isotopic ratios (δ13C), i.e. δ13CO2atm, presumably due to outgassing from the ocean. However, information on the preceding Heinrich Stadials during the last glacial period is scarce. Here we present δ13C records from two species of planktonic foraminifera from the western South Atlantic that reveal major decreases (up to 1 ‰) during Heinrich Stadials 3 and 2. These δ13C decreases are most likely related to millennial-scale periods of weakening of the Atlantic meridional overturning circulation and the consequent increase (decrease) in CO2atm (δ13CO2atm). We hypothesise two mechanisms that could account for the decreases observed in our records, namely strengthening of Southern Ocean deep-water ventilation and weakening of the biological pump. Additionally, we suggest that air–sea gas exchange could have contributed to the observed δ13C decreases. Together with other lines of evidence, our data are consistent with the hypothesis that the CO2 added to the atmosphere during abrupt millennial-scale climate change events of the last glacial period also originated in the ocean and reached the atmosphere by outgassing. The temporal evolution of δ13C during Heinrich Stadials 3 and 2 in our records is characterized by two relative minima separated by a relative maximum. This w structure is also found in North Atlantic and South American records, further suggesting that such a structure is a pervasive feature of Heinrich Stadial 2 and, possibly, also Heinrich Stadial 3.

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