Pleistocene climate change is examined using proxy-climatic records from oxygen isotope data, calcareous and organic-walled marine microfossils, pollen and terrestrial spores deposited during the past 0.9 Ma at ODP Site 646 in the Labrador Sea, 500 km north of the present polar front. Paleotransfer functions applied to planktonic foraminiferal assemblages show relative increases in interglacial summer (3-7-degrees) and winter (3-5-degrees) temperatures and in winter salinity (0.5-2 parts per thousand) for the past 0.4 Ma, but only two earlier intervals (early stage II and stage 17) have changes of comparable magnitude. Coccolith and dinoflagellate cyst accumulation rates show that primary productivity is generally correlated with temperature and salinity changes at the start of interglacials. These productivity peaks lag the ice volume changes by 2-4 ka. Dinocyst blooms seem to precede coccolith peaks, reflecting the tolerance of opportunistic species for large variations in temperature and salinity. Peaks in pollen and spore abundance are strongly correlated with ice volume which controls the position and stability of the polar jet stream in addition to the northern extent of forest vegetation. Time series analysis was made of 7 oceanographic variables (SST summer and winter, surface salinity, coccoliths, dinocysts, planktonic and benthic foraminifera) and 5 other variables (delta-A-18 pollen-spores, percent sand, foraminiferal test fragmentation and reworked palynomorphs). Most variables showed significant power peaks at - 100 Ka, and/or at approximately 41 ka. However, sea surface responses showed minor peaks at 26 and 16 ka, and microfossil productivity also showed significant peaks at 68 Ka. The high latitude Labrador Sea records thus display large non-linear regional responses to climate changes in addition to the effects of orbital insolation forcing at approximately 41 and approximately 23 ka.
