Due to global warming, the Arctic has been changing drastically and rapidly. The changes in the Arctic cryosphere affect not only the Arctic climate and environment but also the global climate system. There is an urgent need to improve the projections of future Arctic climate and environment, including mass loss of the Greenland ice sheet, which affects the global sea level, ocean circulation and global climate. To achieve these goals, we need to advance ice sheet and climate modeling. Long-term records of the past Arctic warmings and their impacts, and the understanding of the mechanisms are necessary. Arctic ice cores have been providing us with valuable information on different time-scales from decadal to orbital time-scales. For example, deep ice cores from Greenland have revealed abrupt warming events in the glacial and deglacial periods and their links to global environmental changes. Multiple ice cores from the Arctic have been used to reconstruct the elevations of the past Greenland ice sheet. Shallow ice cores from circum-Arctic ice caps and Greenland have shown anthropogenic increases of acids, toxic metals etc. after the industrial revolution. This paper briefly reviews the history of ice core studies in the Arctic and discusses future prospects.