Thursday, February 04, 2010, 4:30PM - 5:30PM
Temperature and salinity for the last 2400 years were reconstructed from Mg/Ca ratios and oxygen isotopes from sediment cores from Chesapeake Bay (eastern US) to evaluate Medieval Climate Anomaly (MCA) and Little Ice Age (LIA) climate variability. Results show that MCA temperature maxima reached 16°C between 600 and 950 CE and LIA cooling began about 1000 CE reaching minima of ~8 to 9°C about 1150, 1350, and 1650-1800 CE. MCA warmth in the eastern US preceded the classic European Medieval Warm Period (950-1100 CE) and peak warming in the Nordic Seas (1000-1400 CE). In addition, the inception of LIA cooling was asynchronous across the North Atlantic. Precipitation variability in the eastern US included multiple dry intervals from 600 to 1200 CE, which contrasts with wet medieval conditions in the Caribbean. The eastern US experienced a wet LIA between 1650 and 1800 CE when the Caribbean was drier. These results suggest ocean-atmosphere processes influence MCA-LIA climate variability producing large regional temperature and precipitation anomalies.