Palaeo-sea-ice changes on the North Icelandic shelf during the last millennium:Evidence from diatom records  

作　　者：SHA LongBin JIANG Hui LIU YanGuang ZHAO MeiXun LI DongLing CHEN ZhenLou ZHAO Yun 

机构地区：[1]Key Laboratory of Geographic Information Science, East China Normal University [2]Key Laboratory of Marine Sedimentology and Environmental Geology,First Institute of Oceanography,State Oceanic Administration [3]Key Laboratory of Marine Chemistry Theory and Technology of the Ministry of Education, Ocean University of China [4]Department of City Science, Ningbo University

出　　处：《Science China Earth Sciences》2015年第6期962-970,共9页中国科学（地球科学英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.41406209,41176048);Chinese Polar Environment Comprehensive Investigation & Assessment Programme(Grant No.CHINARE2014-03-02);International Cooperation Project of Chinese Arctic and Antarctic Administration,SOA(Grant No.IC201309)

摘　　要：A high resolution record of sea-ice concentration on the North Icelandic shelf during the last millennium has been reconstructed using a diatom-based sea-ice transfer function. The reconstructed sea-ice record for the top of sediment core MD99–2275 exhibits a slightly increasing trend over the last 1000 years. Prior to AD 1300 sea-ice abundance was generally below the mean value, suggesting the strong influence of warm waters from the Irminger Current during the Medieval Warm Period. A marked increase of sea-ice concentration indicates an abrupt change to colder conditions after AD 1300, corresponding to the onset of the Little Ice Age. The agreement between the reconstructed sea-ice concentration and IP25 data obtained from the same core, as well as with historical records of Icelandic sea ice, suggests that diatoms may provide a valuable tool for future quantitative reconstructions of past sea-ice variability. In addition, agreement between changes in the reconstructed sea-ice record and variations in the abundance of the major diatom components indicates that sea-ice conditions on the North Icelandic shelf are generally strongly influenced by changes in the strength of two different water masses, the cold Polar water periodically derived from the East Greenland Current and the warm Irminger Current derived from the North Atlantic Current. Our proxy evidence also indicates that variations in solar activity have a considerable impact on ocean dynamics, which in turn affects sea-ice abundance.A high resolution record of sea-ice concentration on the North Icelandic shelf during the last millennium has been reconstructed using a diatom-based sea-ice transfer function. The reconstructed sea-ice record for the top of sediment core MD99-2275 ex- hibits a slightly increasing trend over the last 1000 years. Prior to AD 1300 sea-ice abundance was generally below the mean value, suggesting the strong influence of warm waters from the Irminger Current during the Medieval Warm Period. A marked increase of sea-ice concentration indicates an abrupt change to colder conditions after AD 1300, corresponding to the onset of the Little Ice Age. The agreement between the reconstructed sea-ice concentration and IP25 data obtained from the same core, as well as with historical records of Icelandic sea ice, suggests that diatoms may provide a valuable tool for future quantitative reconstructions of past sea-ice variability. In addition, agreement between changes in the reconstructed sea-ice record and vari- ations in the abundance of the major diatom components indicates that sea-ice conditions on the North Icelandic shelf are gen- erally strongly influenced by changes in the strength of two different water masses, the cold Polar water periodically derived from the East Greenland Current and the warm Irminger Current derived from the North Atlantic Current. Our proxy evidence also indicates that variations in solar activity have a considerable impact on ocean dynamics, which in turn affects sea-ice abundance.

关 键 词：palaeo-sea-ice changes North Icelandic shelf Medieval Warm Period Little Ice Age 

分 类 号：P731.15[天文地球—海洋科学] Q949.271[生物学—植物学]