DOCSLIB.ORG

Last Interglacial Ocean Changes in the Bahamas: Climate Teleconnections Between Low and High Latitudes

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Last Interglacial Ocean Changes in the Bahamas: Climate Teleconnections Between Low and High Latitudes Clim. Past, 14, 1361–1375, 2018 https://doi.org/10.5194/cp-14-1361-2018 © Author(s) 2018. This work is distributed under the Creative Commons Attribution 4.0 License. Last interglacial ocean changes in the Bahamas: climate teleconnections between low and high latitudes Anastasia Zhuravleva1 and Henning A. Bauch2 1Academy of Sciences, Humanities and Literature, Mainz c/o GEOMAR Helmholtz Centre for Ocean Research, Wischhofstrasse 1–3, Kiel, 24148, Germany 2Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research c/o GEOMAR Helmholtz Centre for Ocean Research, Wischhofstrasse 1–3, Kiel, 24148, Germany Correspondence: Anastasia Zhuravleva ([email protected]) Received: 26 March 2018 – Discussion started: 11 April 2018 Revised: 29 August 2018 – Accepted: 10 September 2018 – Published: 1 October 2018 Abstract. Paleorecords and modeling studies suggest that Zone (ITCZ) and its associated rainfall (Peterson and Haug, instabilities in the Atlantic Meridional Overturning Cir- 2006). Based on paleorecords and modeling studies, past po- culation (AMOC) strongly affect the low-latitude climate, sitions of the ITCZ are thought to be related to the inter- namely via feedbacks on the Atlantic Intertropical Con- hemispheric thermal contrast (Schneider et al., 2014). In turn, vergence Zone (ITCZ). Despite the pronounced millennial- changes in the thermal contrast could be principally driven scale overturning and climatic variability documented in the by two mechanisms: (1) the precessional cycle and the as- subpolar North Atlantic during the last interglacial period sociated cross-latitudinal distribution of solar insolation, or (MIS 5e), studies on cross-latitudinal teleconnections re- (2) the millennial-scale climatic variability brought about by main very limited. This precludes a full understanding of Atlantic Meridional Overturning Circulation (AMOC) insta- the mechanisms controlling subtropical climate evolution bilities (Wang et al., 2004; Broccoli et al., 2006; Arbuszewski across the last warm cycle. Here, we present new planktic et al., 2013; Schneider et al., 2014). Specifically, millennial- foraminiferal assemblage data combined with δ18O values in scale cold events in the high northern latitudes were linked surface and thermocline-dwelling foraminifera from the Ba- with reduced convection rates of the AMOC, accounting for hamas, a region ideally suited to studying past changes in both a decreased oceanic transport of tropical heat towards the subtropical ocean and atmosphere. Our data reveal that the north and a southward shift of the mean annual posi- the peak sea surface warmth during early MIS 5e was in- tion of the ITCZ (Vellinga and Wood, 2002; Chiang et al., tersected by an abrupt millennial-scale cooling/salinification 2003; Broccoli et al., 2006). Reconstructions from the low- event, which was possibly associated with a sudden south- latitude North Atlantic confirm southward displacements of ward displacement of the mean annual ITCZ position. This the ITCZ coeval with AMOC reductions and reveal a com- atmospheric shift is, in turn, ascribed to the transitional cli- plex hydrographic response within the upper water column, matic regime of early MIS 5e, which was characterized by generally suggesting an accumulation of heat and salt in the persistent ocean freshening in the high latitudes and an un- (sub)tropics (Schmidt et al., 2006a; Carlson et al., 2008; Bahr stable AMOC mode. et al., 2011, 2013). However, there are opposing views on the subtropical sea surface development at times of high-latitude cooling events. While some studies suggest stable or increas- 1 Introduction ing SSTs (Schmidt et al., 2006a; Bahr et al., 2011, 2013), others imply an atmospheric-induced (evaporative) cooling In the low-latitude North Atlantic, wind patterns, the (Chang et al., 2008; Chiang et al., 2008). precipitation–evaporation balance, sea surface temperatures The last interglacial (MIS 5e), which lasted from about (SSTs) and sea surface salinities (SSSs) are strongly depen- ∼ 130 to 115 thousand years before present (hereafter [ka]), dent on the position of the Atlantic Intertropical Convergence Published by Copernicus Publications on behalf of the European Geosciences Union. 1362 A. Zhuravleva and H. A. Bauch: Last interglacial ocean changes in the Bahamas is often referred to as a “warmer than preindustrial” interval our faunal records are then viewed in terms of potential ge- (Hoffman et al., 2017). This period was associated with sig- ographical shifts of the ITCZ. Finally, we compare our new nificantly reduced ice sheets and a sea level rise up to 6–9 m proxy records with published evidence from the regions of above the present levels (Dutton et al., 2015). MIS 5e has also deep water formation to draw further conclusions on the sub- attracted a lot of attention as a possible analog for future cli- polar forcing on the low-latitude climate during MIS 5e. matic development as well as a critical target for validation of climatic models (Masson-Delmotte et al., 2013). Proxy data 2 Regional setting from the North Atlantic demonstrate that the climate of the last interglacial was relatively unstable, involving one or sev- 2.1 Hydrographic context eral cooling events (Maslin et al., 1998; Fronval and Jansen, 1997; Bauch et al., 2012; Irvalı et al., 2012, 2016; Zhuravl- Core MD99-2202 (27◦34.50 N, 78◦57.90 W, 460 m water eva et al., 2017a, b). This climatic variability is thought to depth) was taken from the upper northern slope of the LBB, be strongly related to changes in the AMOC strength (Ad- which is the northernmost shallow-water carbonate platform kins et al., 1997). Thus, recent studies reveal that the AMOC of the Bahamian archipelago. The study area is at the west- abruptly recovered after MIS 6 deglaciation (Termination 2 ern boundary of the wind-driven subtropical gyre (STG), in or T2), i.e., at the onset of MIS 5e, at ∼ 129 ka, but it was in- the vicinity of the Gulf Stream (Fig. 1a), which supplies both terrupted around 127–126 ka (Galaasen et al., 2014; Deaney heat and salt to the high northern latitudes and constitutes the et al., 2017). Despite the pronounced millennial-scale cli- upper cell of the AMOC. matic variability documented in the high northern latitudes, In the western subtropical North Atlantic two distinctly studies on the cross-latitudinal links are very limited (see different layers can be distinguished within the upper 500 m e.g., Cortijo et al., 1999; Schwab et al., 2013; Kandiano et of the water column (Fig. 1c). The uppermost mixed layer al., 2014; Govin et al., 2015; Jiménez-Amat and Zahn, 2015). (upper 50–100 m) is occupied by warm and comparatively This precludes a full understanding of the mechanisms (e.g., fresh waters (T >24 ◦C, S<36:4 psu), which predominantly insolation, oceanic and/or atmospheric forcing versus high- come from the equatorial Atlantic (Schmitz and McCartney, to-low-latitude climate feedbacks) regulating subtropical cli- 1993; Johns et al., 2002). Properties of this water mass vary mate across the last interglacial. significantly on seasonal timescales and are closely related to Given its critical location near the origin of the Gulf the latitudinal migration of the ICTZ (Fig. 1b). During boreal Stream, sediments from the slopes of the shallow-water car- winter (December–April), when the ITCZ is in its southern- bonate platforms of the Bahamian archipelago (Fig. 1) have most position, the Bahama region is dominated by relatively been previously investigated in terms of oceanic and atmo- cool, stormy weather with prevailing northern and northeast- spheric variability (Slowey and Curry, 1995; Roth and Rei- ern trade winds and is affected by cold western fronts, which jmer, 2004, 2005; Chabaud et al., 2016). However, a thor- increase evaporation and vertical convective mixing (e.g., ough study of the last interglacial climatic evolution un- Wilson and Roberts, 1995). During the May to November pe- derpinned by a critical stratigraphical insight is lacking to riod, as the ITCZ moves northward, the LBB region is influ- date. Here, a sediment record from the Little Bahama Bank enced by relatively weakened trade winds from the east and (LBB) region is investigated for possible links between the southeast, increased precipitation and the very warm waters AMOC variability and the ITCZ during the last interglacial of the Atlantic Warm Pool (T >28:5 ◦C), which expand into cycle. Today the LBB region lies at the northern edge of the Bahama region from the Caribbean Sea and the equa- the influence of the Atlantic Warm Pool, which has expan- torial Atlantic (Stramma and Schott, 1999; Wang and Lee, sion that is strongly related to the ITCZ movements (Wang 2007; Levitus et al., 2013). and Lee, 2007; Levitus et al., 2013), making our site par- The mixed layer is underlain by the permanent ther- ticularly sensitive regarding monitoring past shifts of the mocline, which is comprised of a homogeneous pool of ITCZ. Given that geochemical properties of marine sedi- comparatively cool and salty (T <24 ◦C, S>36:4 psu) water ments around carbonate platforms vary in response to sea (Schmitz and Richardson, 1991). These “mode” waters are level fluctuations (e.g., Lantzsch et al., 2007), X-ray fluores- formed in the North Atlantic STG through wintertime sub- cence (XRF) data are being used in combination with stable duction of surface waters generated by wind-driven Ekman isotope and faunal records to strengthen the temporal frame- downwelling and buoyancy flux (Slowey and Curry, 1995). work. Planktic
Load more

Recommended publications
  • Sea Level and Global Ice Volumes from the Last Glacial Maximum to the Holocene
    Sea level and global ice volumes from the Last Glacial Maximum to the Holocene Kurt Lambecka,b,1, Hélène Roubya,b, Anthony Purcella, Yiying Sunc, and Malcolm Sambridgea aResearch School of Earth Sciences, The Australian National University, Canberra, ACT 0200, Australia; bLaboratoire de Géologie de l’École Normale Supérieure, UMR 8538 du CNRS, 75231 Paris, France; and cDepartment of Earth Sciences, University of Hong Kong, Hong Kong, China This contribution is part of the special series of Inaugural Articles by members of the National Academy of Sciences elected in 2009. Contributed by Kurt Lambeck, September 12, 2014 (sent for review July 1, 2014; reviewed by Edouard Bard, Jerry X. Mitrovica, and Peter U. Clark) The major cause of sea-level change during ice ages is the exchange for the Holocene for which the direct measures of past sea level are of water between ice and ocean and the planet’s dynamic response relatively abundant, for example, exhibit differences both in phase to the changing surface load. Inversion of ∼1,000 observations for and in noise characteristics between the two data [compare, for the past 35,000 y from localities far from former ice margins has example, the Holocene parts of oxygen isotope records from the provided new constraints on the fluctuation of ice volume in this Pacific (9) and from two Red Sea cores (10)]. interval. Key results are: (i) a rapid final fall in global sea level of Past sea level is measured with respect to its present position ∼40 m in <2,000 y at the onset of the glacial maximum ∼30,000 y and contains information on both land movement and changes in before present (30 ka BP); (ii) a slow fall to −134 m from 29 to 21 ka ocean volume.
    [Show full text]
  • Holocene Glacier Fluctuations
    Quaternary Science Reviews 111 (2015) 9e34 Contents lists available at ScienceDirect Quaternary Science Reviews journal homepage: www.elsevier.com/locate/quascirev Invited review Holocene glacier fluctuations * Olga N. Solomina a, b, , Raymond S. Bradley c, Dominic A. Hodgson d, Susan Ivy-Ochs e, f, Vincent Jomelli g, Andrew N. Mackintosh h, Atle Nesje i, j, Lewis A. Owen k, Heinz Wanner l, Gregory C. Wiles m, Nicolas E. Young n a Institute of Geography RAS, Staromonetny-29, 119017, Staromonetny, Moscow, Russia b Tomsk State University, Tomsk, Russia c Department of Geosciences, University of Massachusetts, Amherst, MA 012003, USA d British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK e Institute of Particle Physics, ETH Zurich, 8093 Zurich, Switzerland f Institute of Geography, University of Zurich, 8057 Zurich, Switzerland g Universite Paris 1 Pantheon-Sorbonne, CNRS Laboratoire de Geographie Physique, 92195 Meudon, France h Antarctic Research Centre, Victoria University Wellington, New Zealand i Department of Earth Science, University of Bergen, N-5020 Bergen, Norway j Uni Research Klima, Bjerknes Centre for Climate Research, N-5020 Bergen Norway k Department of Geology, University of Cincinnati, Cincinnati, OH 45225, USA l Institute of Geography and Oeschger Centre for Climate Change Research, University of Bern, Switzerland m Department of Geology, The College of Wooster, Wooster, OH 44691, USA n Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY, USA article info abstract Article history: A global overview of glacier advances and retreats (grouped by regions and by millennia) for the Received 15 July 2014 Holocene is compiled from previous studies. The reconstructions of glacier fluctuations are based on Received in revised form 1) mapping and dating moraines defined by 14C, TCN, OSL, lichenometry and tree rings (discontinuous 22 November 2014 records/time series), and 2) sediments from proglacial lakes and speleothems (continuous records/ Accepted 27 November 2014 time series).
    [Show full text]
  • Glacier Fluctuations During the Past 2000 Years
    Quaternary Science Reviews 149 (2016) 61e90 Contents lists available at ScienceDirect Quaternary Science Reviews journal homepage: www.elsevier.com/locate/quascirev Invited review Glacier fluctuations during the past 2000 years * Olga N. Solomina a, , Raymond S. Bradley b, Vincent Jomelli c, Aslaug Geirsdottir d, Darrell S. Kaufman e, Johannes Koch f, Nicholas P. McKay e, Mariano Masiokas g, Gifford Miller h, Atle Nesje i, j, Kurt Nicolussi k, Lewis A. Owen l, Aaron E. Putnam m, n, Heinz Wanner o, Gregory Wiles p, Bao Yang q a Institute of Geography RAS, Staromonetny-29, 119017 Staromonetny, Moscow, Russia b Department of Geosciences, University of Massachusetts, Amherst, MA 01003, USA c Universite Paris 1 Pantheon-Sorbonne, CNRS Laboratoire de Geographie Physique, 92195 Meudon, France d Department of Earth Sciences, University of Iceland, Askja, Sturlugata 7, 101 Reykjavík, Iceland e School of Earth Sciences and Environmental Sustainability, Northern Arizona University, Flagstaff, AZ 86011, USA f Department of Geography, Brandon University, Brandon, MB R7A 6A9, Canada g Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales (IANIGLA), CCT CONICET Mendoza, CC 330 Mendoza, Argentina h INSTAAR and Geological Sciences, University of Colorado Boulder, USA i Department of Earth Science, University of Bergen, Allegaten 41, N-5007 Bergen, Norway j Uni Research Climate AS at Bjerknes Centre for Climate Research, Bergen, Norway k Institute of Geography, University of Innsbruck, Innrain 52, 6020 Innsbruck, Austria l Department of Geology,
    [Show full text]
  • Cirques Have Growth Spurts During Deglacial and Interglacial Periods: Evidence from 10Be and 26Al Nuclide Inventories in the Central and Eastern Pyrenees Y
    Cirques have growth spurts during deglacial and interglacial periods: Evidence from 10Be and 26Al nuclide inventories in the central and eastern Pyrenees Y. Crest, M Delmas, Regis Braucher, Y. Gunnell, M Calvet, A.S.T.E.R. Team To cite this version: Y. Crest, M Delmas, Regis Braucher, Y. Gunnell, M Calvet, et al.. Cirques have growth spurts during deglacial and interglacial periods: Evidence from 10Be and 26Al nuclide inventories in the central and eastern Pyrenees. Geomorphology, Elsevier, 2017, 278, pp.60 - 77. 10.1016/j.geomorph.2016.10.035. hal-01420871 HAL Id: hal-01420871 https://hal-amu.archives-ouvertes.fr/hal-01420871 Submitted on 21 Dec 2016 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Geomorphology 278 (2017) 60–77 Contents lists available at ScienceDirect Geomorphology journal homepage: www.elsevier.com/locate/geomorph Cirques have growth spurts during deglacial and interglacial periods: Evidence from 10Be and 26Al nuclide inventories in the central and eastern Pyrenees Y. Crest a,⁎,M.Delmasa,R.Braucherb, Y. Gunnell c,M.Calveta, ASTER Team b,1: a Univ Perpignan Via-Domitia, UMR 7194 CNRS Histoire Naturelle de l'Homme Préhistorique, 66860 Perpignan Cedex, France b Aix-Marseille Université, CNRS–IRD–Collège de France, UMR 34 CEREGE, Technopôle de l'Environnement Arbois–Méditerranée, BP80, 13545 Aix-en-Provence, France c Univ Lyon Lumière, Department of Geography, UMR 5600 CNRS Environnement Ville Société, 5 avenue Pierre Mendès-France, F-69676 Bron, France article info abstract Article history: Cirques are emblematic landforms of alpine landscapes.
    [Show full text]
  • New Glacier Evidence for Ice-Free Summits During the Life of The
    www.nature.com/scientificreports OPEN New glacier evidence for ice‑free summits during the life of the Tyrolean Iceman Pascal Bohleber1,2*, Margit Schwikowski3,4,5, Martin Stocker‑Waldhuber1, Ling Fang3,5 & Andrea Fischer1 Detailed knowledge of Holocene climate and glaciers dynamics is essential for sustainable development in warming mountain regions. Yet information about Holocene glacier coverage in the Alps before the Little Ice Age stems mostly from studying advances of glacier tongues at lower elevations. Here we present a new approach to reconstructing past glacier low stands and ice‑ free conditions by assessing and dating the oldest ice preserved at high elevations. A previously unexplored ice dome at Weißseespitze summit (3500 m), near where the “Tyrolean Iceman” was found, ofers almost ideal conditions for preserving the original ice formed at the site. The glaciological settings and state‑of‑the‑art micro‑radiocarbon age constraints indicate that the summit has been glaciated for about 5900 years. In combination with known maximum ages of other high Alpine glaciers, we present evidence for an elevation gradient of neoglaciation onset. It reveals that in the Alps only the highest elevation sites remained ice‑covered throughout the Holocene. Just before the life of the Iceman, high Alpine summits were emerging from nearly ice‑free conditions, during the start of a Mid‑Holocene neoglaciation. We demonstrate that, under specifc circumstances, the old ice at the base of high Alpine glaciers is a sensitive archive of glacier change. However, under current melt rates the archive at Weißseespitze and at similar locations will be lost within the next two decades.
    [Show full text]
  • The 'Little Ice Age': Re-Evaluation of An
    THE ‘LITTLE ICE AGE’: RE-EVALUATION OF AN EVOLVING CONCEPT THE ‘LITTLE ICE AGE’: RE-EVALUATION OF AN EVOLVING CONCEPT BY JOHN A. MATTHEWS1 AND KEITH R. BRIFFA2 1 Department of Geography, University of Wales Swansea, Swansea, UK 2 Climatic Research Unit, University of East Anglia, Norwich, UK Matthews, J.A. and Briffa, K.R., 2005: The ‘Little Ice Age’: re- A controversial term evaluation of an evolving concept. Geogr. Ann., 87 A (1): 17–36. The term ‘little ice age’ was coined by Matthes ABSTRACT. This review focuses on the develop- (1939, p. 520) with reference to the phenomenon of ment of the ‘Little Ice Age’ as a glaciological and cli- glacier regrowth or recrudescence in the Sierra Ne- matic concept, and evaluates its current usefulness vada, California, following their melting away in in the light of new data on the glacier and climatic the Hypsithermal of the early Holocene. The mo- variations of the last millennium and of the Holocene. ‘Little Ice Age’ glacierization occurred raines on which Matthes based his initial concept over about 650 years and can be defined most pre- have been described more recently as a product of cisely in the European Alps (c. AD 1300–1950) when ‘neoglaciation’ (Porter and Denton 1967) and the extended glaciers were larger than before or since. term ‘Little Ice Age’ now generally refers only to ‘Little Ice Age’ climate is defined as a shorter time the latest glacier expansion episode of the late interval of about 330 years (c. AD 1570–1900) when Northern Hemisphere summer temperatures (land Holocene.
    [Show full text]
  • The Onset of Neoglaciation in Iceland and the 4.2 Ka Event
    Clim. Past Discuss., https://doi.org/10.5194/cp-2018-130 Manuscript under review for journal Clim. Past Discussion started: 5 October 2018 c Author(s) 2018. CC BY 4.0 License. The onset of Neoglaciation in Iceland and the 4.2 ka event Áslaug Geirsdóttir1, Gifford H. Miller1,2, John T. Andrews2, David J. Harning1,2, Leif S. Anderson1,3 Thor Thordarson1 5 1Faculty of Earth Science, University of Iceland 2INSTAAR/Department of Geological Sciences, University of Colorado Boulder 3Department of Earth Sciences, Simon Fraser University, CANADA Correspondence to: Áslaug Geirsdóttir ([email protected]) 10 Abstract. Strong similarities in Holocene climate reconstructions derived from multiple proxies (BSi, TOC, δ13C, C/N, MS, δ15N) preserved in sediments from both glacial and non-glacial lakes across Iceland indicate a relatively warm early-to-mid Holocene from 10 to 6 ka, overprinted with cold excursions presumably related to meltwater impact on North Atlantic 15 circulation until 7.9 ka. Sediment in lakes from glacial catchments indicates their catchments were ice-free during this interval. Statistical treatment of the high-resolution multiproxy paleoclimate lake records shows that despite great variability in catchment characteristics, the records document more or less synchronous abrupt, cold departures as opposed to the smoothly decreasing trend in Northern Hemisphere summer insolation. Although all lake records document a decline in summer temperature through the Holocene consistent with the regular decline in summer insolation, the onset of significant 20 summer cooling, occurs ~5 ka in high-elevation interior sites, but is variably later in sites closer to the coast, suggesting some combination of changing ocean currents and sea ice modulate the impact from decreasing summer insolation.
    [Show full text]
  • Reappraisal of Chinese Loess Plateau Stratigraphic Sequences Over the Last 30,000 Years: Precursors of an Important Holocene Monsoon Climatic Event
    REAPPRAISAL OF CHINESE LOESS PLATEAU STRATIGRAPHIC SEQUENCES OVER THE LAST 30,000 YEARS: PRECURSORS OF AN IMPORTANT HOLOCENE MONSOON CLIMATIC EVENT 2 WEIJLAN ZHO U,1 ZHISHENG AN,1 A. J. T DULL, D. J. DONAHUE2 and M. J. HEADS ABSTRACT. Through the establishment of radiocarbon chronozones relating common geological events within lacustrine features and eolian sediments from five profiles representative of loess yuan (tablelands), river valley and northwest margin study of the Loess Plateau, we propose a series of stratigraphic divisions within the last 30 ka. The focus of this detailed cool- involves stratigraphic relationships contributing to evidence of Younger Dryas events, with the recognition of cold-dry, pro- wet and cold-dry periods represented within the Heiheze silt, Midiwan peat and Liushuwan eolian sand. The stratigraphic files reflect century-scale fluctuations of the East Asian monsoons. The precursor events enable us to place the Pleistocene/ Holocene boundary at 10,000 BP. INTRODUCTION The late-glacial stratigraphy of North China consists mainly of both lacustrine and eolian sediments. Zheng (1984) made a preliminary stratigraphic subdivision for the Holocene loess. Lei (1992) placed the 04/03 boundary at the interface of SOIL1 with the age of ca. 10,000 BP for the southern part of Loess Plateau. Head, Zhou and Zhou (1989), Zhou and An (1991), Zhou, An and Head (1994) and Zhou, Head and Kaihola (1994) established pretreatment procedures for the separation of organics from paleosol and the extraction of wood cellulose, and further proposed a stratigraphic subdivision for Late Pleistocene loess based on reliable radiocarbon dating. However, since the stratigraphic resolution of the studied profile is not good enough, it is difficult to make a detailed study of the transitional stratigraphy from the last glaciation to post glaciation.
    [Show full text]
  • Holocene Glacier Fluctuations in Alaska
    Quaternary Science Reviews 28 (2009) 2034–2048 Contents lists available at ScienceDirect Quaternary Science Reviews journal homepage: www.elsevier.com/locate/quascirev Holocene glacier fluctuations in Alaska David J. Barclay a,*, Gregory C. Wiles b, Parker E. Calkin c a Geology Department, State University of New York College at Cortland, Cortland, NY 13045, USA b Department of Geology, The College of Wooster, Wooster, OH 44691, USA c Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO 80309, USA article info abstract Article history: This review summarizes forefield and lacustrine records of glacier fluctuations in Alaska during the Received 9 May 2008 Holocene. Following retreat from latest Pleistocene advances, valley glaciers with land-based termini Received in revised form were in retracted positions during the early to middle Holocene. Neoglaciation began in some areas by 15 January 2009 4.0 ka and major advances were underway by 3.0 ka, with perhaps two distinct early Neoglacial Accepted 29 January 2009 expansions centered respectively on 3.3–2.9 and 2.2–2.0 ka. Tree-ring cross-dates of glacially killed trees at two termini in southern Alaska show a major advance in the AD 550s–720s. The subsequent Little Ice Age (LIA) expansion was underway in the AD 1180s–1320s and culminated with two advance phases respectively in the 1540s–1710s and in the 1810s–1880s. The LIA advance was the largest Holocene expansion in southern Alaska, although older late Holocene moraines are preserved on many forefields in northern and interior Alaska. Tidewater glaciers around the rim of the Gulf of Alaska have made major advances throughout the Holocene.
    [Show full text]
  • Bibliography Berke, M.A. Et Al. 2012. a Mid-Holocene Thermal Maximum At
    Bibliography Berke, M.A. et al. 2012. A mid-Holocene thermal maximum at the end of the African Humid Period. Earth and Planetary Science Letters 351, 95-104. Bond, G. et al. 2001. Persistent Solar Influence on North Atlantic Climate During the Holocene. Science Vol. 294, pp. 2130-2136 Bray, J.R. 1968. Glaciation and Solar Activity since the Fifth Century BC and the Solar Cycle. Nature 220, 672-674. Debret M. et al. 2007. The origin of the 1500-year climate cycles in Holocene North-Atlantic records. Clim. Past Discuss., 3, 679–692. Debret, M. et al. 2009. Evidence from wavelet analysis for a mid-Holocene transition in global climate forcing. Quat. Sci. Rev., 28, 2675-2688. Gagan, M.K. et al. 1998. Temperature and surface-ocean water balance of the mid-Holocene tropical western Pacific. Science 279, 5353, 1014-1018. Holmgren, K. et al. 2003. Persistent millennial-scale climatic variability over the past 25,000 years in Southern Africa. Quaternary Science Reviews 22, 21, 2311-2326. Huybers, P. 2006. Early Pleistocene glacial cycles and the integrated summer insolation forcing. Science, 313, 5786, 508-511. Jouzel, J. et al. 2007. Orbital and millennial Antarctic climate variability over the past 800,000 years. science, 317, 5839, 793-796. Kobashi, T. et al. 2007. Precise timing and characterization of abrupt climate change 8200 years ago from air trapped in polar ice. Quaternary Science Reviews, 26, 9, 1212-1222. Kobashi, T. et al. 2013. Causes of Greenland temperature variability over the past 4000 yr: implications for northern hemispheric temperature changes. Climate of the Past, 9, 5, 2299.
    [Show full text]
  • Nonlinear Response of Summer Temperature to Holocene Insolation Forcing in Alaska
    Nonlinear response of summer temperature to Holocene insolation forcing in Alaska Benjamin F. Clegga,b, Ryan Kellyb, Gina H. Clarkeb,1, Ian R. Walkerc, and Feng Sheng Hua,b,d,2 aProgram in Ecology, Evolution, and Conservation Biology, bDepartment of Plant Biology, and dDepartment of Geology, University of Illinois, Urbana, IL 61801; and cBiology and Earth and Environmental Sciences, University of British Columbia Okanagan, Kelowna, BC, Canada V1V 1V7 Edited by Mark H. Thiemens, University of California San Diego, La Jolla, CA, and approved October 21, 2011 (received for review July 8, 2011) Regional climate responses to large-scale forcings, such as pre- century warming, attributed to possible effects of the AO during cessional changes in solar irradiation and increases in anthropo- both periods (4). Some outstanding exceptions to this consistency genic greenhouse gases, may be nonlinear as a result of complex do exist. In particular, Alaska is thought to have experienced interactions among earth system components. Such nonlinear a thermal maximum during the early Holocene, in contrast to behaviors constitute a major source of climate “surprises” with cooling expected from a possible positive phase of AO. The ex- important socioeconomic and ecological implications. Paleorecords istence of Populus woodland as inferred from some Alaskan are key for elucidating patterns and mechanisms of nonlinear pollen records is often cited as evidence of an early-postglacial responses to radiative forcing, but their utility has been greatly thermal maximum (4). However, this interpretation remains con- limited by the paucity of quantitative temperature reconstruc- troversial (5), and paleoecologists have struggled with the conflict tions.
    [Show full text]
  • Alphabetical Glossary of Geomorphology
    International Association of Geomorphologists Association Internationale des Géomorphologues ALPHABETICAL GLOSSARY OF GEOMORPHOLOGY Version 1.0 Prepared for the IAG by Andrew Goudie, July 2014 Suggestions for corrections and additions should be sent to [email protected] Abime A vertical shaft in karstic (limestone) areas Ablation The wasting and removal of material from a rock surface by weathering and erosion, or more specifically from a glacier surface by melting, erosion or calving Ablation till Glacial debris deposited when a glacier melts away Abrasion The mechanical wearing down, scraping, or grinding away of a rock surface by friction, ensuing from collision between particles during their transport in wind, ice, running water, waves or gravity. It is sometimes termed corrosion Abrasion notch An elongated cliff-base hollow (typically 1-2 m high and up to 3m recessed) cut out by abrasion, usually where breaking waves are armed with rock fragments Abrasion platform A smooth, seaward-sloping surface formed by abrasion, extending across a rocky shore and often continuing below low tide level as a broad, very gently sloping surface (plain of marine erosion) formed by long-continued abrasion Abrasion ramp A smooth, seaward-sloping segment formed by abrasion on a rocky shore, usually a few meters wide, close to the cliff base Abyss Either a deep part of the ocean or a ravine or deep gorge Abyssal hill A small hill that rises from the floor of an abyssal plain. They are the most abundant geomorphic structures on the planet Earth, covering more than 30% of the ocean floors Abyssal plain An underwater plain on the deep ocean floor, usually found at depths between 3000 and 6000 m.
    [Show full text]