Although it is generally accepted that the Arctic Ocean is a very sensitive and important region for changes in the global climate, this region is the last major physiographic province of the earth whose short-and long-term geological history is much less known in comparison to other ocean regions. This lack of knowledge is mainly caused by the major technological/logistic problems in reaching this harsh, ice-covered region with normal research vessels and in retrieving long and undisturbed sediment cores. During the the last about 20 years, however, several international and multidisciplinary ship expeditions, including the first scientific drilling on Lomonosov Ridge in 2004, a break-through in Arctic research, were carried out into the central Artic and its surrounding shelf seas. Results from these expeditions have greatly advanced our knowledge on Arctic Ocean paleoenvironments. Published syntheses about the knowledge on Arctic Ocean geology, on the other hand, are based on data available prior to 1990. A comprehensive compilation of data on Arctic Ocean paleoenvironment and its short-and long-term variability based on the huge amount of new data including the ACEX drilling data, has not been available yet. With this book, presenting (1) detailed information on glacio-marine sedimentary processes and geological proxies used for paleoenvironmental reconstructions, and (2) detailed geological data on modern environments, Quaternary variability on different time scales as well as the long-term climate history during Mesozoic-Tertiary times, this gap in knowledge will be filled.