NationMaster - Encyclopedia: Ice core

An ice core is a core sample from the accumulation of snow and ice over many years that have recrystallized and have trapped air bubbles from previous time periods. The composition of these ice cores, especially the presence of hydrogen and oxygen isotopes, provides a picture of the climate at the time. Image File history File links Size of this preview: 67 Ã— 596 pixelsFull resolution (101 Ã— 898 pixel, file size: 20 KB, MIME type: image/jpeg) Text from English Wikipedia follows: Ice Core sample taken from drill. ... Lonnie Thompson. ... History The Byrd Polar center was established in 1960. ... A core sample is a cylindrical section of a naturally occurring medium consistent enough to hold a layered structure. ... Isotopes are any of the several different forms of an element each having different atomic mass (mass number). ...

Because water molecules containing heavier isotopes exhibit a lower vapor pressure, when the temperature falls, the heavier water molecules will condense faster than the normal water molecules. The relative concentrations of the heavier isotopes in the condensate indicate the temperature of condensation at the time, allowing for ice cores to be used in global temperature reconstruction. In addition to the isotope concentration, the air bubbles trapped in the ice cores allow for measurement of the atmospheric concentrations of trace gases, including greenhouse gases carbon dioxide, methane, and nitrous oxide. The air bubbles may also contain traces of aerosols, which are produced in great concentrations during volcanic eruptions. [1]

Typical ice cores are removed from an ice sheet, most commonly from the polar ice caps of Antarctica, Greenland or from high mountain glaciers elsewhere. As the ice forms from the incremental buildup of annual layers of snow, lower layers are older than upper, and an ice core contains ice formed over a range of years. The properties of the ice or inclusions within the ice can then be used to reconstruct a climatic record over the age range of the core. An ice sheet is a mass of glacier ice that covers surrounding terrain and is greater than 50,000 kmÂ² (19,305 mileÂ²). The only current ice sheets are Antarctic and Greenland; during the last ice age at Last Glacial Maximum (LGM) the Laurentide ice sheet covered much of Canada...

Ice cores contain an abundance of climate information. Inclusions in the snow of each year remain in the ice, such as wind-blown dust, ash, bubbles of atmospheric gas and radioactive substances. The variety of climatic proxies is greater than in any other natural recorder of climate, such as tree rings or sediment layers. These include (proxies for) temperature, ocean volume, precipitation, chemistry and gas composition of the lower atmosphere, volcanic eruptions, solar variability, sea-surface productivity, desert extent and forest fires. In climate research, a proxy variable is something that is probably not in itself of any great interest, but from which a variable of interest can be obtained. ... Pinus taeda Cross section showing annual rings Cheraw, South Carolina Dendrochronology or tree-ring dating is the method of scientific dating based on the analysis of tree ring patterns. ... A varve is an annual layer of sediment or sedimentary rock. ... In climate research, a proxy variable is something that is probably not in itself of any great interest, but from which a variable of interest can be obtained. ...

The length of the record depends on the depth of the ice core and varies from a few years up to 800 kyr for the EPICA core. The time resolution (i.e. the shortest time period which can be accurately distinguished) depends on the amount of annual snowfall, and reduces with depth as the ice compacts under the weight of layers accumulating on top of it. Upper layers of ice in a core correspond to a single year or sometimes a single season. Deeper into the ice the layers thin and annual layers become indistinguishable. kyr is occasionally used in geology and astronomy as a unit of one thousand years or millennium. ... Epica may refer to: EPICA , the European Project for Ice Coring in Antarctica Epica (album), an album by the power metal band Kamelot Epica (band), a Dutch symphonic metal band Epica (RAID series), a series of storage arrays developed by Proware Technology Corporation Chevrolet Epica, one of the brand names...

An ice core from the right site can be used to reconstruct an uninterrupted and detailed climate record extending over hundreds of thousands of years, providing information on a wide variety of aspects of climate at each point in time. It is the simultaneity of these properties recorded in the ice that makes ice cores such a powerful tool in paleoclimate research.

Structure of ice sheets and cores

Most ice sheets are formed from snow. Because an ice sheet survives summer, the temperature in that location usually does not warm much above freezing. In many locations in Antarctica the air temperature is always well below the freezing point of water. If the summer temperatures do get above freezing, any ice core record will be severely degraded or completely useless, since meltwater will percolate into the snow. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Taku Glacier is a tidewater glacier located in Taku Inlet in the U.S. state of Alaska, just southeast of the city of Juneau. ...

The surface layer is snow in various forms, with air gaps between snowflakes. As snow continues to accumulate, the buried snow is compressed and forms firn, a grainy material with a texture similar to granulated sugar. Air gaps remain, and some circulation of air continues. As snow accumulates above, the firn continues to densify, and at some point the pores close off and the air is trapped. Because the air continues to circulate until then, the ice age and the age of the gas enclosed are not the same, and may differ by hundreds of years. The gas age–ice age difference is as great as 7 kyr in glacial ice from Vostok. [2]

Under increasing pressure, at some depth the firn is compressed into ice. This depth may range between a few to several tens of meters to typically 100 m for Antarctic cores. Below this level material is frozen in the ice. Ice may appear clear or blue.

Layers can be visually distinguished in firn and in ice to significant depths. In a location on the summit of an ice sheet where there is little flow, accumulation tends to move down and away, creating layers with minimal disturbance. In a location where underlying ice is flowing, deeper layers may have increasingly different characteristics and distortion. Drill cores near bedrock often are challenging to analyze due to distorted flow patterns and composition likely to include materials from the underlying surface. Image File history File links Size of this preview: 800 Ã— 89 pixelsFull resolution (16229 Ã— 1807 pixel, file size: 7. ... Image File history File links Size of this preview: 800 Ã— 89 pixelsFull resolution (16229 Ã— 1807 pixel, file size: 7. ...

Characteristics of firn

The layer of porous firn on Antarctic ice sheets is 50-150 m deep.^[1] It is much less deep on glaciers.

Air in the atmosphere and firn are slowly exchanged by molecular diffusion through pore spaces, because gases move toward regions of lower concentration. Thermal diffusion causes isotope fractionation in firn when there is rapid temperature variation, creating isotope differences which are captured in bubbles when ice is created at the base of firn. There is gas movement due to diffusion in firn, but not convection except very near the surface. Sampling the surface of a glacier. ...

Below the firn is a zone in which seasonal layers alternately have open and closed porosity. These layers are sealed with respect to diffusion. Gas ages increase rapidly with depth in these layers. Various gases are fractionated while bubbles are trapped where firn is converted to ice.^[3]

Coring

A core is collected by separating it from the surrounding material. For material which is sufficiently soft, coring may be done with a hollow tube. Deep core drilling into hard ice, and perhaps underlying bedrock, involves using a hollow drill which actively cuts a cylindrical pathway downward around the core.

When a drill is used, the cutting apparatus is on the bottom end of a drill barrel, the tube which surrounds the core as the drill cuts downward around the edge of the cylindrical core. The length of the drill barrel determines the maximum length of a core sample (6 m at GISP2 and Vostok). Collection of a long core record thus requires many cycles of lowering a drill/barrel assembly, cutting a core 4-6 m in length, raising the assembly to the surface, emptying the core barrel, and preparing a drill/barrel for drilling.

Because deep ice is under pressure and can deform, for cores deeper than about 300 m the hole will tend to close if there is nothing to supply back pressure. The hole is filled with a fluid to keep the hole from closing. The fluid, or mixture of fluids, must simultaneously satisfy criteria for density, low viscosity, frost resistance, as well as workplace safety and environmental compliance. The fluid must also satisfy other criteria, for example those stemming from the analytical methods employed on the ice core. A number of different fluids and fluid combinations have been tried in the past. Since GISP2 (1990-1993) the US Polar Program has utilized a single-component fluid system, n-butyl acetate, but the toxicology, flammability, aggressive solvent nature, and longterm liabilities of n-butyl acetate raises serious questions about its continued application. The European community, including the Russian program, has concentrated on the use of two-component drilling fluid consisting of low-density hydrocarbon base (brown kerosene was used at Vostok) boosted to the density of ice by addition of halogenated-hydrocarbon densifier. Many of the proven densifier products are now considered too toxic, or are no longer available due to efforts to enforce the Montreal Protocol on ozone-depleting substances.^[4] In April 1998 on the Devon Ice Cap filtered lamp oil was used as a drilling fluid. In the Devon core it was observed that below about 150 m the stratigraphy was obscured by microfractures.^[5] 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. ... Kerosene or paraffin oil (British English, not to be confused with the waxy solid also called paraffin wax or just paraffin) is a flammable hydrocarbon liquid. ... The largest Antarctic ozone hole recorded as of September 2000 For other similarly-named agreements, see Montreal Protocol (disambiguation). ... This article does not cite any references or sources. ...

Core processing

Modern practice is to ensure that cores remain uncontaminated, since they are analysed for trace quantities of chemicals and isotopes. They are sealed in plastic bags after drilling and analysed in clean rooms. Image File history File links Download high resolution version (900x600, 91 KB)Sawing the GRIP core on site. ... Image File history File links Download high resolution version (900x600, 91 KB)Sawing the GRIP core on site. ... View of the GRIP site The Greenland Ice Core Project (GRIP) was a multinational European research project, organised through the European Science Foundation. ...

The core is carefully extruded from the barrel; often facilities are designed to accommodate the entire length of the core on a horizontal surface. Drilling fluid will be cleaned off before the core is cut into 1-2 meter sections. Various measurements may be taken during preliminary core processing.

For shipping, cores are packed in Styrofoam boxes protected by shock absorbing bubble-wrap. This article does not cite any references or sources. ... Styrofoam is a trademark name for polystyrene thermal insulation material, manufactured by Dow Chemical Company. ...

Due to the many types of analysis done on core samples, sections of the core are scheduled for specific uses. After the core is ready for further analysis, each section is cut as required for tests. Some testing is done on site, other study will be done later, and a significant fraction of each core segment is reserved for archival storage for future needs.

Projects have used different core-processing strategies. Some projects have only done studies of physical properties in the field, while others have done significantly more study in the field. These differences are reflected in the core processing facilities.

Ice relaxation

Deep ice is under great pressure. When brought to the surface, there is a drastic change in pressure. Due to the internal pressure and varying composition, particularly bubbles, sometimes cores are very brittle and can break or shatter during handling. At Dome C, the first 1000 m were brittle ice. Siple dome encountered it from 400 to 1000 m. It has been found that allowing ice cores to rest for some time (sometimes for a year) makes them become much less brittle. A material is brittle if it is subject to fracture when subjected to stress i. ...

Decompression causes significant volume expansion (called relaxation) due to microcracking and the exsolving of enclathratized gases.^[6] Relaxation may last for months.^[7] During this time, ice cores are stored below -10 °C to prevent cracking due to expansion at higher temperatures. At drilling sites, a relaxation area is often built within existing ice at a depth which allows ice core storage at temperatures below -20 °C. Clathrate hydrates are a class of solids in which gas molecules occupy cages made up of hydrogen-bonded water molecules. ...

It has been observed that the internal structure of ice undergoes distinct changes during relaxation. Changes include much more pronounced cloudy bands and much higher density of "white patches" and bubbles.^[8]

Several techniques have been examined. Cores obtained by hot water drilling at Siple Dome in 1997-1998 underwent appreciably more relaxation than cores obtained with the PICO electro-mechanical drill. In addition, the fact that cores were allowed to remain at the surface at elevated temperature for several days likely promoted the onset of rapid relaxation.^[9] Year 1997 (MCMXCVII) was a common year starting on Wednesday (link will display full 1997 Gregorian calendar). ... Year 1998 (MCMXCVIII) was a common year starting on Thursday (link will display full 1998 Gregorian calendar). ...

Ice core data

Many materials can appear in an ice core. Layers can be measured in several ways to identify changes in composition. Small meteorites may be embedded in the ice. Volcanic eruptions leave identifiable ash layers. Dust in the core can be linked to increased desert area or wind speed. Graph of Vostok CO2/T/dust from Petit 1999 paper. ... Graph of Vostok CO2/T/dust from Petit 1999 paper. ...

Isotopic analysis of the ice in the core can be linked to temperature and global sea level variations. Analysis of the air contained in bubbles in the ice can reveal the palaeocomposition of the atmosphere, in particular CO₂ variations. There are great problems relating the dating of the included bubbles to the dating of the ice, since the bubbles only slowly "close off" after the ice has been deposited. Nonetheless, recent work has tended to show that during deglaciations CO2 increases lags temperature increases by 600 +/- 400 years [10]. Beryllium 10 concentrations are linked to cosmic ray intensity which can be a proxy for solar strength (see proxy). Trapped in a time capsule the same size as the diameter of a human hair, the ore-forming liquid in this inclusion was so hot and contained so much dissolved solids that when it cooled, crystals of halite, sylvite, gypsum, and hematite formed. ... In climate research, a proxy variable is something that is probably not in itself of any great interest, but from which a variable of interest can be obtained. ...

There may be an association between atmospheric nitrates in ice and solar activity. However, recently it was discovered that sunlight triggers chemical changes within top levels of firn which significantly alter the pore air composition. This raises levels of formaldehyde and NOx. Although the remaining levels of nitrates may indeed be indicators of solar activity, there is ongoing investigation of resulting and related effects of effects upon ice core data.^[11]^[12] The chemical compound formaldehyde (also known as methanal) is a gas with a pungent smell. ... Look up nox, Nox in Wiktionary, the free dictionary. ...

Core contamination

Some contamination has been detected in ice cores. The levels of lead on the outside of ice cores is much higher than on the inside.^[13] In ice from the Vostok core (Antarctica), the outer portion of the cores have up to 3 and 2 orders of magnitude higher bacterial density and dissolved organic carbon than the inner portion of the cores, respectively, as a result of drilling and handling.^[14]

Paleoatmospheric sampling

As porous snow consolidates into ice, the air within it is trapped in bubbles in the ice. This process continuously preserves samples of the atmosphere.^[15] In order to retrieve these natural samples the ice is ground at low temperatures, allowing the trapped air to escape. It is then condensed for analysis by gas chromatography or mass spectrometry, revealing gas concentrations and their isotopic composition respectively. Apart from the intrinsic importance of knowing relative gas concentrations (e.g. to estimate the extent of greenhouse warming), their isotopic composition can provide information on the sources of gases. For example CO₂ from fossil-fuel or biomass burning is relatively depleted in ¹³C. See Friedli et al., 1986. Gas-liquid chromatography (GLC), or simply gas chromatography (GC) is a type of chromatography in which the mobile phase is a carrier gas, usually an inert gas such as helium or nitrogen, and the stationary phase is a microscopic layer of liquid on an inert solid support. ... Mass spectrometry (also known as mass spectroscopy (deprecated)[1] or informally, mass-spec and MS) is an analytical technique used to measure the mass-to-charge ratio of ions. ... The greenhouse effect first discovered by Jean Baptiste Joseph Fourier in 1824 is the process by which an atmosphere warms a planet. ...

Dating the air with respect to the ice it is trapped in is problematic. The consolidation of snow to ice necessary to trap the air takes place at depth (the 'trapping depth') once the pressure of overlying snow is great enough. Since air can freely diffuse from the overlying atmosphere throughout the upper unconsolidated layer (the 'firn'), trapped air is younger than the ice surrounding it.

Trapping depth varies with climatic conditions, so the air-ice age difference could vary between 2500 and 6000 years (Barnola et al., 1991). However, air from the overlying atmosphere may not mix uniformly throughout the firn (Battle et al., 1986) as earlier assumed, meaning estimates of the air-ice age difference could be less than imagined. Either way, this age difference is a critical uncertainty in dating ice-core air samples. In addition, gas movement would be different for various gases; for example, larger molecules would be unable to move at a different depth than smaller molecules so the ages of gases at a certain depth may be different. Some gases also have characteristics which affect their inclusion, such as helium not being trapped because it is soluble in ice. General Name, Symbol, Number helium, He, 2 Chemical series noble gases Group, Period, Block 18, 1, s Appearance colorless Standard atomic weight 4. ...

In Law Dome ice cores, the trapping depth at DE08 was found to be 72 m where the age of the ice is 40±1 years; at DE08-2 to be 72 m depth and 40 years; and at DSS to be 66 m depth and 68 years.^[16]

Paleoatmospheric firn studies

At the South Pole, the firn-ice transition depth is at 122 m, with a CO₂ age of about 100 years. Gases involved in ozone depletion, CFCs, chlorocarbons, and bromocarbons, were measured in firn and levels were almost zero at around 1880 except for CH₃Br, which is known to have natural sources.^[17] Similar study of Greenland firn found that CFCs vanished at a depth of 69 m (CO₂ age of 1929).^[18] Image File history File links Measured depth profiles of anthropogenic gases in Greenland firn air. ... Image File history File links Measured depth profiles of anthropogenic gases in Greenland firn air. ... Global monthly average total ozone amount Ozone depletion describes two distinct, but related observations: a slow, steady decline of about 4 percent per decade in the total amount of ozone in Earths stratosphere since around 1980; and a much larger, but seasonal, decrease in stratospheric ozone over Earths... Possible meanings: Certified Financial Consultant Chelsea Football Club Child and Family Canada Chlorofluorocarbon Combined Federal Campaign haloalkane This page concerning a three-letter acronym or abbreviation is a disambiguation pageâ€”a list of articles associated with the same title. ... Year 1880 (MDCCCLXXX) was a leap year starting on Thursday (link will display the full calendar) of the Gregorian calendar (or a leap year starting on Tuesday of the 12-day slower Julian calendar). ... Year 1929 (MCMXXIX) was a common year starting on Tuesday (link will display the full calendar) of the Gregorian calendar. ...

Analysis of the Upper Fremont Glacier ice core showed large levels of chlorine-36 that definitely correspond to the production of that isotope during atmospheric testing of nuclear weapons. This result is interesting because the signal exists despite being on a glacier and undergoing the effects of thawing, refreezing, and associated meltwater percolation.^[19] ³⁶Cl has also been detected in the Dye-3 ice core (Greenland)^[20], and in firn at Vostok.^[21] Image File history File links Upper_Fremont_glacier_ice_cl36. ... Image File history File links Upper_Fremont_glacier_ice_cl36. ... General Name, Symbol, Number chlorine, Cl, 17 Chemical series halogens Group, Period, Block 17, 3, p Appearance yellowish green Standard atomic weight 35. ... The 1960s decade refers to the years from January 1, 1960 to December 31, 1969, inclusive. ... Upper Fremont Glacier is located in the Fitzpatrick Wilderness of Shoshone National Forest in the U.S. state of Wyoming. ... General Name, Symbol, Number chlorine, Cl, 17 Chemical series halogens Group, Period, Block 17, 3, p Appearance yellowish green Standard atomic weight 35. ... The mushroom cloud of the atomic bombing of Nagasaki, Japan, 1945, rose some 18 kilometers (11 mi) above the hypocenter. ...

Studies of gases in firn often involve estimates of changes in gases due to physical processes such as diffusion. However, it has been noted that there also are populations of bacteria in surface snow and firn at the South Pole, although this study has been challenged.^[22]^[23] It had previously been pointed out that anomalies in some trace gases may be explained as due to accumulation of in-situ metabolic trace gas byproducts.^[24]

Dating cores

Shallow cores, or the upper parts of cores in high-accumulation areas, can be dated exactly by counting individual layers, each representing a year. These layers may be visible, related to the nature of the ice; or they may be chemical, related to differential transport in different seasons; or they may be isotopic, reflecting the annual temperature signal (for example, snow from colder periods has less of the heavier isotopes of H and O). Deeper into the core the layers thin out due to ice flow and eventually individual years cannot be distinguished. It may be possible to identify events such as nuclear bomb atmospheric testing's radioisotope layers in the upper levels, and ash layers corresponding to known volcanic eruptions. Volcanic eruptions may be detected by visible ash layers, acidic chemistry, or electrical resistance change. Some composition changes are detected by high-resolution scans of electrical resistance. Lower down the ages are reconstructed by modeling accumulation rate variations and ice flow. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Standard atomic weight 15. ...

Dating is a difficult task. Five different dating methods have been used for Vostok cores, with differences such as 300 years at 100 m depth, 600yr at 200 m, 7000yr at 400 m, 5000yr at 800 m, 6000yr at 1600 m, and 5000yr at 1934 m.^[25]

Different dating methods makes comparison and interpretation difficult. Matching peaks by visual examination of Moulton and Vostok ice cores suggests a time difference of about 10,000 years but proper interpretation requires knowing the reasons for the differences.^[26]

Ice core sites

Ice cores have been taken from many locations around the world. Major efforts have taken place on Greenland and Antarctica.

Sites on Greenland are more susceptible to snow melt than those in Antarctica. In the Antarctic, areas around the Antarctic Peninsula and seas to the west have been found to be affected by ENSO effects. Both of these characteristics have been used to study such variations over long spans of time.^[27] Antarctic Peninsula map Booth Island and Mount Scott flank the narrow Lemaire Channel on the west side of the Antarctic Peninsula. ... Chart of ocean surface temperature anomaly [Â°C] during the last strong El NiÃ±o in December 1997 ENSO (El NiÃ±o-Southern Oscillation) is a global coupled ocean-atmosphere phenomenon. ...

Greenland

Dye 3

The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ...

GRIP/GISP

The GRIP and GISP cores, each about 3000 m long, were drilled by European and US teams respectively on the summit of Greenland. Their usable record stretches back more than 100,000 years into the last interglacial. They agree (in the climatic history recovered) to a few metres above bedrock. However, the lowest portion of these cores cannot be interpreted, probably due to disturbed flow close to the bedrock.^[28] There is evidence the GISP2 cores contain an increasing structural disturbance which casts suspicion on features lasting centuries or more in the bottom 10% of the ice sheet.^[29] The more recent NorthGRIP ice core provides a undisturbed record to approx. 123,000 years before present. The results indicate that Holocene climate has been remarkably stable and have confirmed the occurrence of rapid climatic variation during the last ice age. View of the GRIP site The Greenland Ice Core Project (GRIP) was a multinational European research project, organised through the European Science Foundation. ... 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. ...

NGRIP

The NGRIP drilling site is near the center of Greenland (75.1° N 42.32° W, 2917 m, ice thickness 3085). Drilling began in 1999 and was completed at bedrock in 2003.^[30] The NGRIP site was chosen to extract a long and undisturbed record stretching into the last glacial. NGRIP covers 5 kyr of the Eemian, and shows that temperatures then were roughly as stable as the pre-industrial Holocene temperatures were. Delta-O-18 record from the NGRIP core NGRIP is an abbreviation for the North Greenland Ice Core Project. ... Year 1999 (MCMXCIX) was a common year starting on Friday (link will display full 1999 Gregorian calendar). ... Year 2003 (MMIII) was a common year starting on Wednesday (link displays 2003 calendar) of the Gregorian calendar. ... Two ice core temperature records; the Eemian is at a depth of about 1500-1800 meters in the lower graph The Eemian interglacial era (known as the Sangamon era in North America, the Ipswichian interglacial in the UK, and the Riss-WÃ¼rm interglacial in the Alps) is the second... The Holocene epoch is a geological period that extends from the present day back to about 10,000 radiocarbon years, approximately 11,430 Â± 130 calendar years BP (between 9560 and 9300 BC). ...

Antarctica

Vostok

Up to 2003, the longest core drilled was at Vostok station. It reached back 420,000 years and revealed 4 past glacial cycles. Drilling stopped just above Lake Vostok. The Vostok core was not drilled at a summit, hence ice from deeper down has flowed from upslope; this slightly complicates dating and interpretation. Vostok core data is available.^[31] Image File history File links Download high resolution version (1000x658, 446 KB)Vostok team photo with unprocessed ice cores. ... Image File history File links Download high resolution version (1000x658, 446 KB)Vostok team photo with unprocessed ice cores. ... 2003 is a common year starting on Wednesday of the Gregorian calendar, and also: The International Year of Freshwater The European Disability Year Events January events January 1 Luíz Inácio Lula Da Silva becomes the 37th President of Brazil. ... Vostok, Antarctica is a Russian research station located near the Geomagnetic South Pole (see South Pole), at the center of the East Antarctic Ice Sheet. ... Lake Vostoks location within Antarctica (NASA) Lake Vostok is the largest of more than 70 subglacial lakes in Antarctica. ...

EPICA/Dome C

The EPICA core in Antarctica was drilled at 75° S 123° E (560 km from Vostok) at an altitude of 3,233 m, near Dome C. The ice thickness is 3,309 +/-22 m and the core was drilled to 3,190 m. Present-day annual average air temperature is -54.5 °C and snow accumulation 25 mm/y. Information about the core was first published in Nature on June 10, 2004. The core went back 720,000 years and revealed 8 previous glacial cycles. Image File history File links Epica_do18_plot. ... Image File history File links Epica_do18_plot. ... The European Project for Ice Coring in Antarctica (EPICA) is a multinational European project for deep ice core drilling in Antarctica. ... The European Project for Ice Coring in Antarctica (EPICA) is a multinational European project for deep ice core drilling in Antarctica. ... Distance signs near the station-Courtesy of Paolo Calisse [1]. Dome C, also known as Dome Circe or Dome Charlie, located at at an altitude of 3,233 m or 10,607 ft above sea level, is one of several summits or domes of the Antarctic Ice Sheet. ... June 10 is the 161st day of the year (162nd in leap years) in the Gregorian calendar. ... Year 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ...

Dome F

Two deep ice cores were drilled near the Dome F summit (77°19′S, 39°42′E, altitude 3,810 m). The first drilling started in August 1995, reached a depth of 2503 m in December 1996 and covers a period back to 320,000 years. The second drilling started in 2003, was carried out during three subsequent austral summers from 2003/2004 until 2005/2006, and by then a depth of 3,029 m was reached. This core greatly extends the climatic record of the first core, and, according to first estimates, it reaches back until 730,000 years. Japanese Antarctica bases Dome F, also known as Dome Fuji (ãƒ‰ãƒ¼ãƒ å¯Œå£« DÅmu Fuji) or Valkyrjedomen, is located in east Queen Maud Land at . ... Japanese Antarctica bases Dome F, also known as Dome Fuji (ãƒ‰ãƒ¼ãƒ å¯Œå£« DÅmu Fuji) or Valkyrjedomen, is located in east Queen Maud Land at . ...

Non-polar cores

The non-polar ice caps, such as found on mountain tops, were traditionally ignored as serious places to drill ice cores because it was generally believed the ice would not be more than a few thousand years old, however since the 1970s ice has been found that is older, with clear chronological dating and climate signals going as far back as the beginning of the most recent ice age. Although polar cores have the clearest and longest chronological record, four-times or more as long, ice cores from tropical regions offer data and insights not available from polar cores and have been very influential in advancing understanding of the planets climate history and mechanisms.

Mountain ice cores have been retrieved in the Andes in South America, Mount Kilimanjaro in Africa, Tibet, various locations in the Himalayas, Alaska, Russia and elsewhere. Mountain ice cores are logistically very difficult to obtain. The drilling equipment must be carried by hand, organized as a mountaineering expedition with multiple stage camps, to altitudes upwards of 20,000 feet (helicopters are not safe), and the multi-ton ice cores must then be transported back down the mountain, all requiring mountaineering skills and equipment and logistics and working at low oxygen in extreme environments in remote third world countries. Scientists may stay at high altitude on the ice caps for up 20 to 50 days setting altitude endurance records that even professional climbers do not obtain. American scientist Lonnie Thompson has been pioneering this area since the 1970s, developing light-weight drilling equipment that can be carried by porters, solar-powered electricity, and a team of mountaineering-scientists.^[32] Because glaciers are retreating rapidly world-wide, some important glaciers are now no longer scientifically viable for taking cores, and many more glacier sites will continue to be lost, the "Snows of Mount Kilimanjaro" (Hemingway) for example could be gone by 2015. [33] Planes view of the Andes, Peru. ... Kilimanjaro, formerly Kaiser-Wilhelm-Spitze, is an inactive stratovolcano in north-eastern Tanzania. ... Tibet (see Name section below for other spellings) is a plateau region in Central Asia and the indigenous home to the Tibetan people. ... Himalaya, see Himalaya (film). ... Official language(s) English[1] Spoken language(s) English 85. ... Lonnie Thompson. ...

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