Planktic foraminiferal data and temperature reconstructions of upper Atlantic Water in the eastern Fram Strait over the past ~2100 years from sediment core MSM5/5-712-1. Spielhagen, et al., 2011

Planktic foraminiferal data and temperature reconstructions of upper Atlantic Water in the eastern Fram Strait over the past ~2100 years from sediment core MSM5/5-712-1. Thin lines are raw data, bold lines are three-point running means. Black triangles on the age scale mark calibrated accelerator mass spectrometry 14C ages. (A) Fluxes of polar and subpolar planktic foraminifers (100- to 250-μm fraction). (B) Percentage of subpolar planktic foraminifers in the 100- to 250-μm fraction. (C) Summer temperatures at 50-m water depth (red) calculated by the SIMMAX Modern Analog Technique. Gray bars mark averages until 1835 CE and 1890 to 2007 CE. Blue line is the normalized Atlantic Water core temperature (AWCT) record (standard deviations) from the Arctic Ocean (1895 to 2002; 6-year averages) obtained from (21). (D) Summer temperatures (purple) calculated from Mg/Ca ratios in planktic foraminifers N. pachyderma (sinistral). Gray bars mark averages until 1835 CE and 1890 to 2007 CE. Blue line is the sea ice margin anomaly (11-year means, less ice is up) in the Barents Sea (BS) obtained from (5). Dashed lines mark less reliable data before 1850 CE. (E) Terrestrial Arctic [green, from (6)] and Northern Hemisphere [black, 25-year means, from (19)] temperature anomaly records with reference to the 980 to 1800 CE and 1961 to 1990 CE averages, respectively. Abstract: The Arctic is responding more rapidly to global warming than most other areas on our planet. Northward-flowing Atlantic Water is the major means of heat advection toward the Arctic and strongly affects the sea ice distribution. Records of its natural variability are critical for the understanding of feedback mechanisms and the future of the Arctic climate system, but continuous historical records reach back only ~150 years. Here, we present a multidecadal-scale record of ocean temperature variations during the past 2000 years, derived from marine sediments off Western Svalbard (79°N). We find that early–21st-century temperatures of Atlantic Water entering the Arctic Ocean are unprecedented over the past 2000 years and are presumably linked to the Arctic amplification of global warming.

Spielhagen, et al., “Enhanced Modern Heat Transfer to the Arctic by Warm Atlantic Water,” Science 28 January 2011: Vol. 331 no. 6016 pp. 450-453 DOI: 10.1126/science.1197397