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 (for shallow holes) or powered drills; they can reach depths of over two miles (3.2 km), and contain ice up to 800,000 years old.
The physical properties of the ice and of material trapped in it can be used to reconstruct the climate over the age range of the core. The proportions of different oxygen and hydrogen isotopes provide information about ancient temperatures, and the air trapped in tiny bubbles can be analysed to determine the level of atmospheric gases such as carbon dioxide. Since heat flow in a large ice sheet is very slow, the borehole temperature is another indicator of temperature in the past. These data can be combined to find the climate model that best fits all the available data.
Impurities in ice cores may depend on location. Coastal areas are more likely to include material of marine origin, such as sea salt ions. Greenland ice cores contain layers of wind-blown dust that correlate with cold, dry periods in the past, when cold deserts were scoured by wind. Radioactive elements, either of natural origin or created by nuclear testing, can be used to date the layers of ice. Some volcanic events that were sufficiently powerful to send material around the globe have left a signature in many different cores that can be used to synchronise their time scales.
Ice cores have been studied since the early 20th century, and several cores were drilled as a result of the International Geophysical Year (1957–1958). Depths of over 400 m were reached, a record which was extended in the 1960s to 2164 m at Byrd Station in Antarctica. Soviet ice drilling projects in Antarctica include decades of work at Vostok Station, with the deepest core reaching 3769 m. Numerous other deep cores in the Antarctic have been completed over the years, including the West Antarctic Ice Sheet project, and cores managed by the British Antarctic Survey and the International Trans-Antarctic Scientific Expedition. In Greenland, a sequence of collaborative projects began in the 1970s with the Greenland Ice Sheet Project; there have been multiple follow-up projects, with the most recent, the East Greenland Ice-Core Project, originally expected to complete a deep core in east Greenland in 2020 but since postponed.[1]
^Berwyn, Bob (27 March 2020). "Coronavirus Already Hindering Climate Science, But the Worst Disruptions Are Likely Yet to Come". Retrieved 5 April 2020.
An icecore 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...
height about 200,000 years ago. Several tephra layers encountered in icecores at Mount Waesche and Byrd Station have been attributed to Mount Takahe...
evidence, going back millions of years. More recently, information from icecores covers the period from 800,000 years before the present time until now...
temperature on Earth of −89.2 °C (−128.6 °F; 184.0 K). Research includes icecore drilling and magnetometry. Vostok (Russian for 'east') was named after...
1628 BCE. The Greenland icecore chronology offset was independently confirmed by other teams and adopted into Greenland IceCore Chronology 2021 (GICC21)...
The Greenland IceCore Project (GRIP) was a research project organized through the European Science Foundation (ESF). The project ran from 1989 to 1995...
mentioned gases are now able to be seen with the new icecore samples from the European Project for IceCoring in Antarctica (EPICA) Dome C in Antarctica over...
Dye 3 is an icecore site and previously part of the DYE section of the Distant Early Warning (DEW) line, located at (65°11′N 43°49′W / 65.183°N 43.817°W...
possible composition from traditional stony/iron, to ice or to fluid metallic hydrogen. Gas giant cores are proportionally much smaller than those of terrestrial...
Greenland icecores provide estimates for the start and end of the Younger Dryas. The analysis of Greenland Summit icecores, as part of the Greenland Ice Sheet...
West Antarctic icecores with the Greenland Ice Sheet Project Two GISP2; they suggested a synchronous global cooling. An ocean sediment core from the eastern...
comparing the details from continent to continent difficult (see picture of icecore data below for differences). Around 12,800 years ago, the Younger Dryas...
in the Camp Century 1963 core recurred in the Renland 1985 icecore. The Renland icecore from East Greenland apparently covers a full glacial cycle from...
upper boundary). The proposed section is the North Greenland IceCore Project icecore 75° 06' N 42° 18' W. The lower boundary of the Pleistocene Series...
1458 sulfate spike was incorrectly assigned to be 1452 because previous icecore work had poor time resolution. The exact location of this eruption is uncertain...
Geologists working in different regions are studying sea levels, peat bogs, and ice-core samples, using a variety of methods, with a view toward further verifying...
to Core sample. Defining Coring Archived 2015-07-18 at the Wayback Machine Core from Walden Pond Archived 2019-04-18 at the Wayback Machine IceCore Dating...
Mountain glaciers and the polar ice caps/ice sheets provide much data in paleoclimatology. Ice-coring projects in the ice caps of Greenland and Antarctica...
site of the North Greenland IceCore Project (NGRIP or NorthGRIP) is near the center of Greenland (75.1 N, 42.32 W, 2917 m, ice thickness 3085). Drilling...
led to icecoring drills being developed in the 1950s and 1960s, and there are now many different coring drills in use. For obtaining icecores from deep...
regularly shed ice in what is known as ice calving. Sediment released from calved and melting ice sinks accumulates on the seafloor, and sediment cores from places...
winter") or impact events (meteorite or comet). In 2015, revision of polar icecore chronologies dated sulfate deposits and a cryptotephra layer to the exact...
depending on the existence of separate sulfur gas in the Toba magma chamber. Icecore records estimate the sulfur emission on the order of 1×1014 g. Greenland...
The European Project for IceCoring in Antarctica (EPICA) is a multinational European project for deep icecore drilling in Antarctica. Its main objective...
sky, like thunder. Icecore chronology and tree ring dating allows extremely precise dating to the exact calendar year of any ice depth in the Common...
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