NOAA/WDS Paleoclimatology - North Icelandic Shelf Annually Resolved d18O Data Over the Last Millennium

Due to the lack of absolutely-dated oceanographic information prior to the modern instrumental period, there is currently significant debate as to the role played by North Atlantic Ocean dynamics in previous climate transitions (e.g., Medieval Climate Anomaly-Little Ice Age, MCA-LIA). Here we present analyses of a millennial-length, annually-resolved and absolutely-dated marine ?18O archive. Our record of oxygen isotope ratios in the shell of the long-lived marine bivalve Arctica islandica (?18O-shell), from the North Icelandic Shelf, linked to seawater density variability, demonstrate that solar and volcanic forcing coupled with ocean circulation dynamics are key drivers of climate variability over the last millennium. During the pre-industrial period (AD 1000-1800) variability in the sub-polar North Atlantic leads changes in Northern Hemisphere surface air temperatures at multi-decadal timescales indicating that North Atlantic Ocean dynamics played an active role in modulating the response of the atmosphere to solar and volcanic forcing.