thumb|right|View of the GRIP site at [[Summit Camp]]
The Greenland Ice Core Project (GRIP) was a research project organized through the European Science Foundation (ESF). The project ran from 1989 to 1995, with drilling seasons from 1990 to 1992. In 1988, the project was accepted as an ESF-associated program, and the fieldwork was started in Greenland in the summer of 1989.
GRIP aimed to collect and investigate 3000-meter-long ice cores drilled at the apex of the Greenland ice sheet, also known as Summit Camp. Funding came from eight European nations (Belgium, Denmark, France, Germany, Iceland, Italy, Switzerland, and the United Kingdom), and from the European Union. The mass loss of ice sheets and glaciers causes sea levels to rise, terrestrial albedo to decline, and patterns of ocean circulation to change. It is predicted that the sea level will rise by approximately 7 meters if all the ice melts. The rise in sea levels due to ice sheet glaciers' melt would make it impossible for people to live in coastal regions. Using the limited paleoclimate data, researchers have shown that the extent of ice in Greenland has changed significantly over time, and this suggests that the change in size is due to a variety of physical environmental factors. The best estimates based on the paleoclimate data show that the Greenland ice sheet is significantly reduced by even a small increase in the negative effects of climate change.
Results and findings
thumb|right|A portion of the coreStudies of nuclear isotopes and various atmospheric constituents provide detailed records of climate change over 100,000 years. From the analysis of the oxygen isotope ratio of the GRIP core excavated in 1992, it became clear that abrupt climate change occurred in Greenland during the last glacial period. This happened more than 20 times. It further became clear that the warm and cold periods alternated. Near the bottom of the GRIP core, oxygen isotope ratios fluctuated sharply; this was initially interpreted as an indication of repeated violent climate change during the last interglacial period in Greenland.
Techniques
The first drilling of the Greenland Ice Core Project went only a few hundred meters into the glacier ice.
But from 1989 to 1992 GRIP successfully drilled a 3029-meter ice core to the bed of the Greenland ice sheet at Summit (). In 1991, ice cores 783 to 2482 meters long were drilled, and an 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 -26 °C. including the North Greenland core, and are no longer believed to represent climate events. The interglacial climate of the Eemian Stage appears to have been as stable as the Holocene.
Three different types of ice sheet core drills were used in the project, differing mainly in the depths they can drill to. It became clear that the ice layer structure was disturbed by folds at the bottom of the ice sheet in both cores, indicating that the interpretation that there was severe climate change during the final interglacial period may be incorrect.
NorthGRIP
NorthGRIP aimed to collect ice during the final interglacial period, but the bottom of the ice sheet had melted, and it was not possible to excavate those samples. As a result, temperatures estimated to be as high as 5 °C above those at present were observed from some of the ice cores that could be collected in the middle of the last interglacial period; the Greenland ice sheet apparently existed even in such a warm climate.
thumb|GRIP temperatures compared with NorthGRIP|center
The shaded lines represent the uncertainty of the estimates due to inaccuracies in the analysis and adjustments in the isotope model. This shows that it is extremely rare for the ice sheet to melt even in the hot summer in Greenland. Rather, the ice sheet surface melted during the final interglacial period (the Eemian) because of the methane and rare gases collected from NEEM's ice core.
EastGRIP
Previous ice core drilling projects, including GRIP, were carried out at sites where horizontal ice flow is as small as possible. In contrast, the latest EastGRIP research was conducted upstream of the Northeast Greenland Ice Stream. This is the most significant active ice stream in Greenland.
In addition, the ice depths in the earlier Greenland ice cores that corresponded to the warm period of the early Holocene were very fragile. It was almost impossible to collect highly accurate chemical and gas analysis data with high time resolution from the traditional Greenland ice cores. In view of this difficulty, EastGRIP installed a cold temperature chamber to keep the drilled ice below -30 °C immediately after the drilling, and efforts were made to minimize the destruction of ice cores by eliminating small steps of several tens of microns in the core field processing. The cold air prevents the expansion of air bubbles and keeps the ice from breaking.