Sea Ice and sagas: stable isotope evidence for two millennia of North Atlantic seasonality on the north Icelandic shelf

• Main Authors: Kristin A. Dietrich, William P. Patterson, Chris Holmden
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Greenland; Iceland; North Atlantic; Sea ice
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.132.4973; http://geochemistry.usask.ca/bill/courses/earth system science/iceland_science_preprint.pdf

δ 18 O values of mollusks recovered from near-shore marine cores in northwest Iceland quantify significant variation in seasonal temperature over the period from ~360 BC to ~AD 1660. Core sedimentological characteristics were used to select twenty-six bivalve specimens that represent intervals of particular climatic interest. Carbonate powder was sequentially micromilled concordant with growth banding, and analyzed for stable oxygen (δ 18 O) and carbon (δ 13 C) isotope values. Because δ 18 O values record sub-seasonal temperature variation over the lifetime of the bivalves, these data provide the first 2000-year secular record of North Atlantic seasonality from c. 360 cal yr BC to cal yr AD 1660. Notable cold periods (360 BC to 240 BC; AD 410; AD 1380 to 1420) and warm periods (230 BC to AD 140; AD 640 to 760) are resolved in terms of contrast between summer and winter temperatures and seasonal temperature variability. Literature from the Viking Age (c. 790 to 1070) documenting the establishment of Norse colonies in Iceland and Greenland permits comparisons of the δ 18 O-derived temperature record and historical descriptions of climate. We posit that this comparison demonstrates the impact of seasonal climatic extremes on the establishment, development, and in some cases, collapse of societies in the North Atlantic.