The Younger Dryas in palynological records from the northern Northwest Atlantic: Does the terrestrial record lag the marine and air records?

Major changes in both pollen and dinocyst assemblages are recorded during the Younger Dryas in Bay of Islands and are associated with large drops in air and sea surface temperatures, and sea surface salinity. The changes in vegetation are similar with those observed at other sites in Newfoundland. Dinoflagellate cyst assemblages also show similar species succession as nearby sites from the Gulf of St. Lawrence and Laurentian Channel. The amplitude of changes in air temperature (a 7 °C drop) is similar to those recorded in northeastern North America. In the sea-surface, temperature dropped by 7 °C, salinity by 4 psu and the sea ice cover duration increased by 7 months. Sea-surface and air temperatures started cooling 250 and 110 years before the start of the YD, hence there is a 140 years delay between ocean and atmosphere. A warming trend is seen in the marine record 310 years before the end of the YD, while vegetation and air temperatures started recovering after the end of the event, some 370 years later. The major lithological and vegetation changes observed during the YD period in eastern North America might actually represent the full impacts of the cooling associated with the YD, since the cooling trend actually started before the start of the YD period, as defined by radiocarbon dates and pollen zones.