Palaeoceanography and climate changes off North Iceland during the last millennium: comparison of foraminifera, diatoms and ice-rafted debris with instrumental and documentary data

摘要

Planktonic and benthic foraminifera data, as well as ice-rafted debris data, from a Pb-210-dated multicore (B05-2006-MC04) covering the last ca. 130 a on the North Icelandic shelf (similar to 450 m water depth) are compared with instrumental data and with the Sea Ice Index for the area. There is indication of a strong connection between atmospheric and oceanic changes. A pronounced rise in the sea Surface temperature is documented by the proxy data to occur at AD 1910, which is shortly before the rise in the air temperature in the region at ca. AD 1920 but coinciding with the first rise in instrumentally measured annual sea surface temperature. The Great Salinity Anomaly in the 1960s,and early 1970s is, however, not clearly expressed in the environmental proxies. There has been a mean sedimentation rate of about 300 cm ka(-1) at the core site, based on a tephrochronological age model for the core MD99-2275. The foraminifera and diatom assemblages show increased influence of Atlantic water masses during the time interval ca. AD 800-1300 (the so-called Medieval Warm Period or Medieval Climatic Anomaly), whereas the interval ca. AD 1300-1910 (encompassing the Little Ice Age) was characterised by decreased sea surface temperatures due to intensified influence of Arctic waters of the East Icelandic Current.