Non-linear Holocene climate evolution in the North Atlantic: A high-resolution, multi-proxy record of glacier activity and environmental change from Hvítárvatn, central Iceland

Darren J. Larsen, Gifford H. Miller, Áslaug Geirsdóttir, Sædís Ólafsdóttir

Research output: Contribution to journalArticlepeer-review

87 Scopus citations

Abstract

Iceland is well situated to monitor North Atlantic Holocene climate variability. Terrestrial sites there offer the potential for well-dated, high-resolution, continuous records of environmental change and/or glacier activity. Laminated sediments from the proglacial lake Hvítárvatn provide a continuous record of environmental change and the development of the adjacent Langjökull ice cap for the past 10.2 ka. Replicate lake sediment cores, collected from multiple locations in the basin, are placed in a secure geochronology by splicing a varve chronology for the past 3 ka with a tephra-constrained, paleomagnetic secular variation derived chronology for older sediments. Multiple proxies, including sedimentation rate, bulk density, ice-rafted debris, sediment organic matter, biogenic silica, and diatom abundance, allow annual to multi-decadal resolution and reveal a dynamic Holocene terrestrial climate. Following regional deglaciation of the main Iceland Ice Sheet, summer temperatures were high enough that mountain ice caps had already melted, or were contributing insignificant sediment to the lake. Pronounced increases in sedimentation rate, sediment density, and the influx of terrestrial organic matter, between 8.7 and 7.9 ka suggest early Holocene warmth was interrupted by two distinct pulses of cold summers leading to widespread landscape destabilization and possibly glacier growth. The Holocene thermal maximum (HTM; 7.9 to 5.5 ka) was characterized by high within-lake productivity and ice-free conditions in the watershed. Neoglaciation is recorded as a non-linear transition toward cooler summers, landscape destabilization, and the inception and expansion of Langjökull beginning ca 5.5 ka, with notable increases in ice cap size and landscape instability at 4.2 and 3.0 ka. The past two millennia are characterized by the abrupt onset of sustained cold periods at ca 550 and 1250 AD, separated by an interval of relative warmth from ca 950 to 1150 AD. The greatest Holocene extent of Langjökull occurred in the nineteenth century and is coincident with peak landscape instability, followed by ice recession throughout the twentieth century.

Original languageEnglish (US)
Pages (from-to)14-25
Number of pages12
JournalQuaternary Science Reviews
Volume39
DOIs
StatePublished - Apr 16 2012

Bibliographical note

Funding Information:
Sediment cores were obtained using the DOSECC GLAD-200 coring system with financial support from the US National Science Foundation (OPP-0138010) and the Icelandic Centre of Research, RANNIS (# 040233021 ). Additional support was provided by the Icelandic fund for graduate students , grant # R09031/5264 , and by the VAST (Volcanism in the Arctic System) Project, through NSF-OPP-ARC 0714074 and RANNIS # 0070272011 . Thanks to Thorsteinn Jónsson, Sveinbjörn Steinthórsson, and Doug Schnurrenberger for their great work in the field, and to the people at the LRC, University of Minnesota, for laboratory assistance. This manuscript was improved by comments from two anonymous reviewers.

Copyright:
Copyright 2012 Elsevier B.V., All rights reserved.

Keywords

  • 8.2 Event
  • Glacier erosion
  • Holocene paleoclimate
  • Holocene thermal maximum
  • Iceland
  • Lake sediment
  • Little Ice Age
  • Medieval warm period
  • Neoglaciation
  • Soil erosion

Continental Scientific Drilling Facility tags

  • GLAD4

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