An ice core is a core sample that is typically removed from an ice sheet or a high mountain glacier. Since the ice forms from the incremental buildup of annual layers of snow, lower layers are older than upper ones, and an ice core contains ice formed over a range of years. Cores are drilled with hand augers or powered drills; they can reach depths of over two miles (3.2 km), and contain ice up to 800,000 years old.
In glaciology, an ice sheet, also known as a continental glacier, is a mass of glacial ice that covers surrounding terrain and is greater than 50,000 km2 (19,000 sq mi). The only current ice sheets are the Antarctic ice sheet and the Greenland ice sheet. Ice sheets are bigger than ice shelves or alpine glaciers. Masses of ice covering less than 50,000 km2 are termed an ice cap. An ice cap will typically feed a series of glaciers around its periphery.
In the study of past climates ("paleoclimatology"), climate proxies are preserved physical characteristics of the past that stand in for direct meteorological measurements and enable scientists to reconstruct the climatic conditions over a longer fraction of the Earth's history. Reliable global records of climate only began in the 1880s, and proxies provide the only means for scientists to determine climatic patterns before record-keeping began.
The Eemian was the interglacial period which began about 130,000 years ago at the end of the Penultimate Glacial Period and ended about 115,000 years ago at the beginning of the Last Glacial Period. It corresponds to Marine Isotope Stage 5e. Although sometimes referred to as the "last interglacial", it was the second-to-latest interglacial period of the current Ice Age, the most recent being the Holocene which extends to the present day. The prevailing Eemian climate was, on average, around 1 to 2 degrees Celsius warmer than that of the Holocene. During the Eemian, the proportion of CO2 in the atmosphere was about 280 parts per million.
Dansgaard–Oeschger events, named after palaeoclimatologists Willi Dansgaard and Hans Oeschger, are rapid climate fluctuations that occurred 25 times during the last glacial period. Some scientists say that the events occur quasi-periodically with a recurrence time being a multiple of 1,470 years, but this is debated. The comparable climate cyclicity during the Holocene is referred to as Bond events.
The global temperature record shows the fluctuations of the temperature of the atmosphere and the oceans through various spans of time. There are numerous estimates of temperatures since the end of the Pleistocene glaciation, particularly during the current Holocene epoch. Some temperature information is available through geologic evidence, going back millions of years. More recently, information from ice cores covers the period from 800,000 years before the present time until now. A study of the paleoclimate covers the time period from 12,000 years ago to the present. Tree rings and measurements from ice cores can give evidence about the global temperature from 1,000-2,000 years before the present until now. The most detailed information exists since 1850, when methodical thermometer-based records began. Modifications on the Stevenson-type screen were made for uniform instrument measurements around 1880.
The European Project for Ice Coring in Antarctica (EPICA) is a multinational European project for deep ice core drilling in Antarctica. Its main objective is to obtain full documentation of the climatic and atmospheric record archived in Antarctic ice by drilling and analyzing two ice cores and comparing these with their Greenland counterparts (GRIP and GISP). Evaluation of these records will provide information about the natural climate variability and mechanisms of rapid climatic changes during the last glacial epoch.
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.
The Greenland Ice Sheet Project (GISP) was a decade-long project to drill ice cores in Greenland that involved scientists and funding agencies from Denmark, Switzerland and the United States. Besides the U.S. National Science Foundation (NSF), funding was provided by the Swiss National Science Foundation and the Danish Commission for Scientific Research in Greenland. The ice cores provide a proxy archive of temperature and atmospheric constituents that help to understand past climate variations.
The Older Dryas was a stadial (cold) period between the Bølling and Allerød interstadials, about 14,000 years Before Present, towards the end of the Pleistocene. Its date range is not well defined, with estimates varying by 400 years, but its duration is agreed to have been around two centuries.
Dye 3 is an ice core site and previously part of the DYE section of the Distant Early Warning (DEW) line, located at in Greenland. As a DEW line base, it was disbanded in years 1990/1991.
The WAIS Divide is the ice flow divide on the West Antarctic Ice Sheet (WAIS) which is a linear boundary that separates the region where the ice flows to the Ross Sea, from the region where the ice flows to the Weddell Sea. It is similar to a continental hydrographic divide.
NEEM Camp was a small research facility on the northern Greenland Ice Sheet, used as a base for ice core drilling. It was located about 313 km east of the closest coast, Peabody Bay in northern Greenland, 275 km northwest of the historical ice sheet camp North Ice, and 484 km east-northeast of Siorapaluk, the closest settlement. There was one heavy-duty tent for accommodation of the researchers during summer. Access was by skiway .
Dorthe Dahl-Jensen is a Danish palaeoclimatology professor and researcher at the Centre for Ice and Climate at the Niels Bohr Institute, University of Copenhagen in Denmark. Her primary field is the study of ice and climate, specifically the reconstruction of climate records from ice cores and borehole data; ice flow models to date ice cores; continuum mechanical properties of anisotropic ice; ice in the solar system; and the history and evolution of the Greenland Ice Sheet.
KumikoGoto-Azuma is an Antarctic palaeoclimatologist and glaciologist and Director of the Ice Core Research Center at the National Institute of Polar Research, Japan.
The East Greenland Ice-Core Project, known as EGRIP, is a scientific project that plans to retrieve an ice core from the Northeast Greenland ice stream. The first season in the field was 2015; the project was expected to be drilling through to the base of the ice sheet by 2020.
Ice drilling allows scientists studying glaciers and ice sheets to gain access to what is beneath the ice, to take measurements along the interior of the ice, and to retrieve samples. Instruments can be placed in the drilled holes to record temperature, pressure, speed, direction of movement, and for other scientific research, such as neutrino detection.
Siwan Davies FLSW is a Welsh professor of Physical Geography in the department of science at Swansea University.
False bottom is a form of sea ice that forms at the interface between meltwater and seawater via the process of double-diffusive convection of heat and salt.
