from GRIP Studies of nuclear isotopes and various atmospheric constituents provide detailed records of climate change over 100,000 years ago. From analysis results of the oxygen isotope ratio of the GRIP core excavated in 1992, it became clear that in Greenland, abrupt climate change occurred during the last glacial period. This happened more than 20 times. Furthermore, it became clear that both the warm and cold periods were repeated alternately. Near the bottom of the GRIP core, oxygen isotope ratios fluctuated sharply, initially interpreted as repeated violent climate change during the last interglacial period in Greenland. Drilling techniques and drill development GRIP successfully drilled a 3029-metre ice core to the bed of the Greenland ice sheet at Summit from 1989 to 1992 at . The first ice core drilling of the Greenland ice cap, projects Camp Century and DYE3, contained only a few hundred meters of glacier ice. GRIP's drilled more than 3 kilometres of core. In 1991, GRIP ice cores 783 to 2482 metres long were drilled, and the ice core was drilled to bedrock in 1992. The ice core was first taken to the University of Copenhagen in Denmark, where it was stored in a cold room at minus -26 °C. After that, the ice core was divided into five parts with a length of about 300 to 400 mm and shipped to Japan as the GRIP ice core segment. They are expecting to obtain and clarify a wide range of information related to past and present climate and environmental changes that can be analysed from the ice. Moreover, it is clear how glaciers are an important source of information, as GRIP can reveal up to 500,000 years of evidence by collecting annual layers (ESF, 2010). Studies of isotopes and various atmospheric constituents in the core have revealed a detailed record of climate variability reaching more than 100,000 years back in time. The results indicate that Holocene climate has been remarkably stable and has confirmed the occurrence of rapid climatic variation during the last ice age (the Wisconsin). Delta-O-18 variations observed in the core part believed to date from the Eemian Stage have not been confirmed by other records including the NGRIP core and are now believed not to represent climate events: the interglacial climate of Eemian Stage appears to have been as stable as the Holocene. Mainly, 3 different types of ice sheet core drills were used