Climate variations in eastern Hudson bay over the past 3000 years

Palynological analyses of the marine sediment core AMD0509-20 collected north of Whapmagoostui-Kuujjuarapik in Nunavik were performed to investigate past changes in climate and sea-surface conditions based on pollen and spores and dinoflagellate cysts, respectively. Our results show relatively warm sea-surface temperatures before 2600 BP, about 2 °C higher than at present in summer, in addition to higher salinity suggesting relatively low freshwater inputs, thus low precipitation over the watershed. After 2400 years BP, an abrupt drop in sea-surface temperatures was recorded, followed by a decrease in salinity particularly pronounced until ∼2000 years BP. After 1600 years BP, summer sea-surface temperatures and salinity stabilized around current values. The changes recorded in surface waters during the late Holocene can be associated with a regional shift in the hydroclimatic regime that led to a gradual decline of spruce (Picea) in pollen assemblages.