M.M. Fauria et al., Climate Dynamics, Unprecedented low twentieth century winter sea ice extent in the Western Nordic Seas since A.D. 1200

Climate Dynamics (June 23, 2009); DOI: 10.1007/s00382-009-0610-z

Unprecedented low twentieth century winter sea ice extent in the Western Nordic Seas since A.D. 1200

M. Macias Fauria^{1, 2, 5, 10} , A. Grinsted^{4, 3}, S. Helama², J. Moore^{3, 6, 7}, M. Timonen⁵, T. Martma⁹, E. Isaksson⁸ and M. Eronen²

(1)	Biogeoscience Institute, University of Calgary, Calgary, AB, Canada

(2)	Department of Geology, University of Helsinki, Helsinki, Finland

(3)	Arctic Centre, University of Lapland, Rovaniemi, Finland

(4)	Centre for Ice and Climate, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark

(5)	Rovaniemi Research Station, Finnish Forest Institute, Rovaniemi, Finland

(6)	Thule Institute, University of Oulu, Oulu, Finland

(7)	College of Global Change and Earth System Science, Beijing Normal University, Beijing, China

(8)	Polar Environmental Centre, Norwegian Polar Institute, Tromsø, Norway

(9)	Institute of Geology, Tallinn University of Technology, Tallinn, Estonia

(10)	Department of Ecology, Faculty of Biology, University of Barcelona, Av. Diagonal 645, 08028 Barcelona, Spain

(Received 1 October 2008, accepted 9 June 2009, published online 23 June 2009.)

Abstract

We reconstructed decadal to centennial variability of maximum sea ice extent in the Western Nordic Seas for A.D. 1200–1997 using a combination of a regional tree-ring chronology from the timberline area in Fennoscandia and δ¹⁸O from the Lomonosovfonna ice core in Svalbard. The reconstruction successfully explained 59% of the variance in sea ice extent based on the calibration period 1864–1997. The significance of the reconstruction statistics (reduction of error, coefficient of efficiency) is computed for the first time against a realistic noise background. The twentieth century sustained the lowest sea ice extent values since A.D. 1200: low sea ice extent also occurred before (mid-seventeenth and mid-eighteenth centuries, early fifteenth and late thirteenth centuries), but these periods were in no case as persistent as in the twentieth century. Largest sea ice extent values occurred from the seventeenth to the nineteenth centuries, during the Little Ice Age (LIA), with relatively smaller sea ice-covered area during the sixteenth century. Moderate sea ice extent occurred during thirteenth–fifteenth centuries. Reconstructed sea ice extent variability is dominated by decadal oscillations, frequently associated with decadal components of the North Atlantic Oscillation/Arctic Oscillation (NAO/AO), and multi-decadal lower frequency oscillations operating at ~50–120 year. Sea ice extent and NAO showed a non-stationary relationship during the observational period. The present low sea ice extent is unique over the last 800 years, and results from a decline started in late-nineteenth century after the LIA.

M. Macias Fauria, e-mail: mmaciasf@ucalgary.ca

Link to abstract: http://www.springerlink.com/content/922v30um17650817/