2000 Years of Climate Variablity from Arctic Lakes

Paleolimnological Evidence of the Response of the Central Canadian Treeline Zone to Radiative Forcing and Hemispheric Patterns of Temperature Change over the past 2000 years

macdonald, g.m., porinchu, d.f., rolland, n., kremenetsky, k.v., and kaufman, d.s.

Lake S41

Abstract

Study Location

Lake S41 (unofficial designation) is located in the Northwest Territories of Canada at 63˚ 43.11’ N 109˚ 19.07’ W and ~418 m a.s.l. It a very small body of water of approximately 1/3 ha in size with a total depth of ice cover and water of 4.4 m. The lake lies at the southern edge of the arctic tundra biome adjacent to the forest-tundra ecotone.

Climate Proxy

Loss on ignition (LOI) , biogenic silica (BSi), and chironomid-community assemblage:

  • We used multiple proxies to infer climate change during the last 2000 years at Lake S41. LOI and BSi are related to lake productivity and has been shown to be positively related to temperature in the study area. Chironomid community composition in small lakes within the study region has been shown to correspond to treeline and decreasing temperatures northward from the treeline zone.

Results

LOI, BSi, and chironomid-community assemblage suggest a general correspondence between global radiative forcing, hemispheric temperature response patterns and climate and limnic environmental change at treeline in central Canada. LOI and BSi are positively correlated (r = 0.41, p ≤ 0.05) and are lowest during the Little Ice Age (1300-1700 AD). Both increase during the 20th century and exceed values during the Medievel Warm Period (800-1300 AD). Chironomid inferred air and water temperatures show a decrease during the LIA, but do not indicate any strong increase in temperature over the past century.

References

  • Hoyt, D. V., & K. H. Schatten, 1998a. Group sunspot numbers: A new solar activity reconstruction. Part 1. Solar Physics, 179: 189-219.
  • Hoyt, D. V., & K. H. Schatten, 1998b. Group sunspot numbers: A new solar activity reconstruction. Part 2. Solar Physics, 181: 491-512.
  • Keeling, C.D., T.P. Whorf & the Carbon Dioxide Research Group, 2004. Atmospheric CO2 concentrations (ppmv) derived from in situ air samples collected at Mauna Loa Observatory, Hawaii. Scripps Institution of Oceanography, University of California, La Jolla, California. http://cdiac.ornl.gov/ftp/maunaloa-co2/maunaloa.co2
  • Moberg, A., D.M. Sonechkin, K. Holmgren, N.M. Datsenko & W. Karlén. 2005. Highly variable Northern Hemisphere temperatures reconstructed from low- and high-resolution proxy data. Nature 433: 613-617.
  • Monnin, E., E.J. Steig, U. Siegenthaler, K. Kawamura, J. Schwander, B. Stauffer, T.F. Stocker, D.L. Morse, J.-M. Barnola, B. Bellier, D. Raynaud & H. Fischer, 2004. Evidence for substantial accumulation rate variability in Antarctica during the Holocene, through synchronization of CO2 in the Taylor Dome, Dome C and DML ice cores. Earth and Planetary Science Letters, 224, 45-54, doi: 10.1016/j.epsl.2004.05.007.
  • Solanki, S.K., I.G. Usoskin, B. Kromer, M. Schüssler & J. Beer, 2004. An unusually active Sun during recent decades compared to the previous 11,000 years. Nature 431: 1084-1087
  • Szeicz, J.M. & G.M. MacDonald, 1995. Dendroclimatic Reconstruction of Summer

    Temperatures in Northwestern Canada Since A.D. 1638 based on Age Dependent Modelling. Quat. Res. 44: 257-266.

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