Abrupt Holocene climate change and potential response to solar forcing in western Canada

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Abstract

Several abrupt climate events during the Holocene, including the widely documented oscillation at 8.2 thousand years before present (ka), are attributed to changes in the North Atlantic thermohaline circulation. Additional mechanisms, such as interactions between atmospheric circulation, ice-sheet dynamics, and the influence of solar irradiance, also have been proposed to explain abrupt climatic events, but evidence remains elusive. This study presents evidence from multi-proxy analyses on the Holocene sediments of Eleanor Lake, interior British Columbia. Climatic inferences from our decadal-resolution record of biogenic silica (BSi) abundance are supported by changes in diatom and pollen assemblages from the same core and correlations with existing regional climate records. The BSi record reveals abrupt and persistent climatic shifts at 10.2, 9.3, and 8.5 ka, the latter two of which are coeval with major collapses of the Laurentide Ice Sheet. The record also reveals a short-term cooling at 8.2 ka that is distinct from the 8.5 ka event and similar in magnitude to several other late-Holocene coolings. BSi is correlated with solar-irradiance indices (r = 0.43–0.61), but the correlation is opposite in sign to that expected from direct solar forcing and weakens after 8 ka. Possible mechanisms causing the abrupt and persistent climate changes of the early Holocene include 1) sudden losses of ice and proglacial lake extent, causing a shift in the meridional structure of atmospheric circulation, 2) a possible link between solar minima and El Niño-like conditions that are correlated with warm spring temperature in interior British Columbia, and 3) the influence of solar irradiance variability on the position of the polar jet, possibly via effects on the strength of the glacial anticyclone.

Highlights

► Multiproxy lake sediment record from Eleanor Lake, BC, reveals abrupt early Holocene climate change. ► Biogenic silica in lake sediment is correlated with temperature during spring or early summer. ► Abrupt climate change is coeval with deglaciation events. ► Early Holocene climate changes may be linked to solar activity effects on El Nino-like conditions.

Introduction

Understanding the mechanisms of abrupt climate change requires identification of such events in high-resolution paleoclimate records and associating them with forcing factors that may have pushed the climate system past a threshold (Alley et al., 2003, Denton et al., 2010). Apart from the events attributable to thermohaline circulation shutdown in the North Atlantic during deglaciation (e.g., Kleiven et al., 2008), evidence of abrupt and long-lasting (>several centuries) climate change events during the Holocene with plausible alternative mechanisms remains scarce in many regions. However, several mechanisms have been proposed, including abrupt shifts in the jet stream upstream of ice sheets associated with rapid deglaciation (Wunsch, 2006) and solar variability as a modulator of centennial-scale climatic fluctuations (Björck et al., 2001, Bond et al., 2001, Hu et al., 2003).

The scattered evidence of abrupt Holocene climate change no-doubt reflects the paucity of high-resolution records of sensitive climate proxies in regions that experienced abrupt events. Candidate regions for detecting abrupt Holocene climate events include transitions between climatic regimes and air-mass dominance (Kirby et al., 2002). One such region is eastern British Columbia in western Canada, where winter onshore flow collides with polar air masses, producing abundant snowfall, and where summer convective rainfall also is frequent. In this study, we analyzed sediments from Eleanor Lake (Fig. 1; 52°7′N, 119°18′W; 677 m above sea level) in east-central British Columbia to infer patterns and drivers of Holocene climatic change. While the regional climate may be sensitive to large-scale forcing, paleolimnological approaches to climate reconstruction present challenges because the year-round wet climate may result in little climatic sensitivity of the biogeochemistry of lake water or of the assemblages and productivity of the diatom flora (Battarbee, 2000). It is possible, however, that the cool summer climate and variable ice-off dates affect springtime water temperature, nutrient dynamics, diatom species assemblages, and productivity (Smol and Douglas, 2007). Here we infer Holocene climatic change in the Eleanor Lake area from a variety of sediment measurements, with a focus on the biogenic silica (BSi) content, diatom assemblages, and pollen assemblages. These inferences are compared with nearby independent temperature-sensitive climate proxy records. Furthermore, we compared the Eleanor Lake climate record with commonly used proxies of solar activity, as several recent studies have shown that millennial-scale climate fluctuations throughout the Holocene are correlated with ice-core and tree-ring proxies of solar activity (e.g., Björck et al., 2001, Bond et al., 2001, Hu et al., 2003, Marshall et al., 2007, Marchitto et al., 2010).

Section snippets

Geomorphic and hydrologic setting

Eleanor Lake is a 9.5-ha, 19-m deep, kettle lake in the valley floor of the North Thompson River in the town of Blue River, British Columbia. The climate of the region is cool and moist, with an average July temperature of 16.3 °C and an average annual precipitation of 1002 mm, 30% of which falls as snow (Fig. 1). The bedrock is classified in the Shuswap Assemblage, dominated by metamorphic rocks of quartzofeldspathic gneiss and biotite-quartz schist (Massey et al., 2005). The lake has no

Core collection and chronology

Two parallel cores were obtained from the deepest location of the lake using a modified square-rod Livingstone piston corer from an anchored platform. Cores were extruded and wrapped in the field and split lengthwise in the laboratory. The upper-most 57-cm of sediment was obtained using a clear polycarbonate tube fitted with a piston. The surface-sediment core was sectioned into plastic bags at 1-cm intervals in the field. The chronology of the sediments is based on nine 14C ages on plant

Sediment chronology and characteristics

The 682-cm sediment core is characterized as brown gyttja with microlaminations and black banding, three volcanic tephras, and in the basal 35 cm, alternating clay and organic sediment overlying coarse sand and gravel. The basal calibrated 14C age of the core is 10.85 ka, and the sequence of 14C dates shows no age reversals. However, one date from a marginal quantity of unidentifiable plant material fell out of line with neighboring dates and had a large standard deviation (Table 1). This date is

Multi-proxy evidence from Eleanor Lake

BSi and organic matter (estimated by loss-on-ignition) together comprise on average 75% of the sediment dry weight (Fig. 2), and their fractions are negatively correlated. Specifically, BSi has a strong negative correlation with % organic nitrogen (% ON) and % organic carbon (% OC) (r = −0.86 and −0.88, respectively; Fig 5). While fluctuations in one component (e.g., OC) affect the percent of the other component (e.g., BSi), we note that if computing % BSi and % OC relative to non-BSi mineral

Abrupt climate shifts

Several abrupt climate changes have been detected during the early Holocene throughout the northern hemisphere and have been related to the dynamics of the Laurentide Ice Sheet (Alley et al., 2003). The BSi record from Eleanor Lake also displays many early Holocene abrupt changes, which are supported by diatom and pollen data from the same core. For many of these events, however, the direction of the climate change, the timing of the events, and the persistence following the abrupt change

Acknowledgements

Funding was provided by the National Science Foundation award DEB-0212917 (FSH, DGG, SCF) and the Packard Foundation (FSH). Laboratory work was assisted by Lauren Roschen (biogenic silica, CHN, loss-on-ignition, and pollen processing), Jian Tian (X-ray diffraction measurements), and Paul Henne (210Pb measurements). We thank Tom Brown for handling the AMS radiocarbon dates. We greatly appreciate comments from P.J. Bartlein and two anonymous reviewers.

References (75)

  • G. Plunkett et al.

    Determining the Sun’s influence on Lateglacial and Holocene climates: a focus on climate response to centennial-scale solar forcing at 2800 cal. BP

    Quat. Sci. Rev.

    (2008)
  • B. Shuman et al.

    Parallel climate and vegetation responses to the early Holocene collapse of the Laurentide Ice Sheet

    Quat. Sci. Rev.

    (2002)
  • C. Wunsch

    Abrupt climate change: an alternative view

    Quat. Res.

    (2006)
  • R.B. Alley et al.

    Abrupt climate change

    Science

    (2003)
  • R.W. Battarbee et al.

    Diatoms

  • S. Björck et al.

    High-resolution analyses of an early Holocene climate event may imply decreased solar forcing as an important climate trigger

    Geology

    (2001)
  • G. Bond et al.

    Persistent solar influence on north Atlantic climate during the Holocene

    Science

    (2001)
  • J.P. Bradbury

    A climatic–limnologic model of diatom succession for paleolimnological interpretation of varved sediments at Elk Lake, Minnesota

    J. Paleolimnol.

    (1988)
  • CAPE Members

    Holocene paleoclimate data from the Arctic: testing models of global climate change

    Quat. Sci. Rev.

    (2001)
  • J.J. Clague et al.

    Improved age estimates for the White River and Bridge River tephras

    Can. J. Earth Sci.

    (1995)
  • W.S. Cleveland

    Robust locally weighted regression and smoothing scatterplots

    J. Am. Stat. Assoc.

    (1979)
  • B.F. Cumming et al.

    Diatoms from British Columbia (Canada) Lakes and their relationship to salinity, nutrients and other limnological variables

    Biblioth. Diatomol.

    (1995)
  • T.J. Daley et al.

    Terrestrial climate signal of the “8200 yr BP cold event” in the Labrador Sea region

    Geology

    (2009)
  • G.H. Denton et al.

    The Last Glacial termination

    Science

    (2010)
  • Dyke, A.S., Moore, A., Robertson, L., 2003. Deglaciation of North America. Geological Survey of Canada Open File...
  • K. Faegri et al.

    Textbook of Pollen Analysis

    (1992)
  • D. Fleitmann et al.

    Evidence for a widespread climatic anomaly at around 9.2 ka before present

    Paleoceanography

    (2008)
  • F.F. Foit et al.

    The tephra stratigraphy of two lakes in south-central British Columbia, Canada and its implications for mid-late Holocene volcanic activity at Glacier Peak and Mount St. Helens, Washington, USA

    Can. J. Earth Sci.

    (2004)
  • J.M. Galloway et al.

    Hydrological change in the central interior of British Columbia, Canada: diatom and pollen evidence of millennial-to-centennial scale change over the Holocene

    Journal of Paleolimnology

    (2011)
  • D.J. Hallett et al.

    A 1000-year record of forest fire, drought and lake level change in southeastern British Columbia

    Holocene

    (2003)
  • C. Hillaire-Marcel et al.

    Lake Agassiz final drainage event in the northwest North Atlantic

    Geophys. Res. Lett.

    (2007)
  • J. Hilton

    A conceptual framework for predicting the occurrence of sediment focusing and sediment redistribution in small lakes

    Limnol. Oceanogr.

    (1985)
  • K.R. Hodder et al.

    Pattern and timing of sediment infill at glacier-fed Mud Lake: implications for lateglacial and Holocene environments in the Monashee Mountain region of British Columbia, Canada

    Holocene

    (2006)
  • K.R. Hodder et al.

    Glaciolacustrine varved sediment as an alpine hydroclimatic proxy

    J. Paleolimnol.

    (2007)
  • F.S. Hu et al.

    Abrupt changes in North American climate during the early Holocene

    Nature

    (1999)
  • F.S. Hu et al.

    Cyclic variation and solar forcing of Holocene climate in the Alaskan subarctic

    Science

    (2003)
  • S.J. Interlandi et al.

    Responses of phytoplankton to varied resource availability in large lakes of the Greater Yellowstone Ecosystem

    Limnol. Oceanogr.

    (1999)
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    Present address: School of Geographical & Earth Sciences, University of Glasgow, East Quadrangle, University Avenue, Glasgow G12 8QQ, UK.

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