2650:
506.9 m in April 1970; by 1973 a depth of 952 m had been reached. A subsequent hole, Vostok 2, drilled from 1971 to 1976, reached 450 m, and Vostok 3 reached 2202 m in 1985 after six drilling seasons. Vostok 3 was the first core to retrieve ice from the previous glacial period, 150,000 years ago. Drilling was interrupted by a fire at the camp in 1982, but further drilling began in 1984, eventually reaching 2546 m in 1989. A fifth Vostok core was begun in 1990, reached 3661 m in 2007, and was later extended to 3769 m. The estimated age of the ice is 420,000 years at 3310 m depth; below that point it is difficult to interpret the data reliably because of mixing of the ice.
2727:(GISP), a multinational investigation into the Greenland ice sheet that lasted until 1981. Years of field work were required to determine the ideal location for a deep core; the field work included several intermediate-depth cores, at Dye 3 (372 m in 1971), Milcent (398 m in 1973) and Crete (405 m in 1974), among others. A location in north-central Greenland was selected as ideal, but financial constraints forced the group to drill at Dye 3 instead, beginning in 1979. The hole reached bedrock at 2037 m, in 1981. Two holes, 30 km apart, were eventually drilled at the north-central location in the early 1990s by two groups:
555:
fluid. In mineral drilling, special machinery can bring core samples to the surface at bottom-hole pressure, but this is too expensive for the inaccessible locations of most drilling sites. Keeping the processing facilities at very low temperatures limits thermal shocks. Cores are most brittle at the surface, so another approach is to break them into 1 m lengths in the hole. Extruding the core from the drill barrel into a net helps keep it together if it shatters. Brittle cores are also often allowed to rest in storage at the drill site for some time, up to a full year between drilling seasons, to let the ice gradually relax.
514:
2316:
1412:
761:
1872:, show strong seasonal variation. In some cases there are contributions from more than one source to a given species: for example, Ca comes from dust as well as from marine sources; the marine input is much greater than the dust input and so although the two sources peak at different times of the year, the overall signal shows a peak in the winter, when the marine input is at a maximum. Seasonal signals can be erased at sites where the accumulation is low, by surface winds; in these cases it is not possible to date individual layers of ice between two reference layers.
2494:
774:
the alternating layers remain visible, which makes it possible to count down a core and determine the age of each layer. As the depth increases to the point where the ice structure changes to a clathrate, the bubbles are no longer visible, and the layers can no longer be seen. Dust layers may now become visible. Ice from
Greenland cores contains dust carried by wind; the dust appears most strongly in late winter, and appears as cloudy grey layers. These layers are stronger and easier to see at times in the past when the Earth's climate was cold, dry, and windy.
526:
1428:
367:
157:
2619:
2458:, ice in a well is melted to provide a water supply, leaving micrometeorites behind. These have been collected by a robotic "vacuum cleaner" and examined, leading to improved estimates of their flux and mass distribution. The well is not an ice core, but the age of the ice that was melted is known, so the age of the recovered particles can be determined. The well becomes about 10 m deeper each year, so micrometeorites collected in a given year are about 100 years older than those from the previous year.
584:, there has to be a way to determine the relationship between depth and age of the ice. The simplest approach is to count layers of ice that correspond to the original annual layers of snow, but this is not always possible. An alternative is to model the ice accumulation and flow to predict how long it takes a given snowfall to reach a particular depth. Another method is to correlate radionuclides or trace atmospheric gases with other timescales such as periodicities in the earth's
255:
177:. Firn is not dense enough to prevent air from escaping; but at a density of about 830 kg/m it turns to ice, and the air within is sealed into bubbles that capture the composition of the atmosphere at the time the ice formed. The depth at which this occurs varies with location, but in Greenland and the Antarctic it ranges from 64 m to 115 m. Because the rate of snowfall varies from site to site, the age of the firn when it turns to ice varies a great deal. At
2654:
22:
465:
2735:, was launched as an international consortium led by Denmark. Drilling began in 1996; the first hole had to be abandoned at 1400 m in 1997, and a new hole was begun in 1999, reaching 3085 m in 2003. The hole did not reach bedrock, but terminated at a subglacial river. The core provided climatic data back to 123,000 years ago, which covered part of the last interglacial period. The subsequent North Greenland Eemian (
2731:, a European consortium, and GISP-2, a group of US universities. GRIP reached bedrock at 3029 m in 1992, and GISP-2 reached bedrock at 3053 m the following year. Both cores were limited to about 100,000 years of climatic information, and since this was thought to be connected to the topography of the rock underlying the ice sheet at the drill sites, a new site was selected 200 km north of GRIP, and a new project,
384:
drills, designed for use without drilling fluid, were limited in depth as a result; later versions were modified to work in fluid-filled holes but this slowed down trip times, and these drills retained the problems of the earlier models. In addition, thermal drills are typically bulky and can be impractical to use in areas where there are logistical difficulties. More recent modifications include the use of
1742:
reference layer. This was done, for example, in an analysis of the climate for the period from 535 to 550 AD, which was thought to be influenced by an otherwise unknown tropical eruption in about 533 AD; but which turned out to be caused by two eruptions, one in 535 or early 536 AD, and a second one in 539 or 540 AD. There are also more ancient reference points, such as the eruption of
782:
the calculation of a melt-feature percentage (MF): an MF of 100% would mean that every year's deposit of snow showed evidence of melting. MF calculations are averaged over multiple sites or long time periods in order to smooth the data. Plots of MF data over time reveal variations in the climate, and have shown that since the late 20th century melting rates have been increasing.
380:
above the core. When the core is retrieved, the cuttings chamber is emptied for the next run. Some drills have been designed to retrieve a second annular core outside the central core, and in these drills the space between the two cores can be used for circulation. Cable-suspended drills have proved to be the most reliable design for deep ice drilling.
1154:
388:, which eliminates the need for heating the drill assembly and hence reduces the power needs of the drill. Hot-water drills use jets of hot water at the drill head to melt the water around the core. The drawbacks are that it is difficult to accurately control the dimensions of the borehole, the core cannot easily be kept sterile, and the heat may cause
741:, about 11,700 years ago, is now formally defined with reference to data on Greenland ice cores. Formal definitions of stratigraphic boundaries allow scientists in different locations to correlate their findings. These often involve fossil records, which are not present in ice cores, but cores have extremely precise
5910:
Souney, Joseph M.; Twickler, Mark S.; Hargreaves, Geoffrey M.; Bencivengo, Brian M.; Kippenhan, Matthew J.; Johnson, Jay A.; Cravens, Eric D.; Neff, Peter D.; Nunn, Richard M.; Orsi, Anais J.; Popp, Trevor J.; Rhoades, John F.; Vaughn, Bruce H.; Voigt, Donald E.; Wong, Gifford J.; Taylor, Kendrick C.
1641:
within the firn layer causes other changes that can be measured. Gravity causes heavier molecules to be enriched at the bottom of a gas column, with the amount of enrichment depending on the difference in mass between the molecules. Colder temperatures cause heavier molecules to be more enriched at
603:
The density and size of the bubbles trapped in ice provide an indication of crystal size at the time they formed. The size of a crystal is related to its growth rate, which in turn depends on the temperature, so the properties of the bubbles can be combined with information on accumulation rates and
595:
through firn, so the ice at a given depth may be substantially older than the gases trapped in it. As a result, there are two chronologies for a given ice core: one for the ice, and one for the trapped gases. To determine the relationship between the two, models have been developed for the depth at
488:
A log is kept with information about the core, including its length and the depth it was retrieved from, and the core may be marked to show its orientation. It is usually cut into shorter sections, the standard length in the US being one metre. The cores are then stored on site, usually in a space
358:
drills allow the removal of the core barrel from the drill assembly while it is still at the bottom of the borehole. The core barrel is hoisted to the surface, and the core removed; the barrel is lowered again and reconnected to the drill assembly. Another alternative is flexible drill-stem rigs, in
781:
When there is summer melting, the melted snow refreezes lower in the snow and firn, and the resulting layer of ice has very few bubbles so is easy to recognise in a visual examination of a core. Identification of these layers, both visually and by measuring density of the core against depth, allows
554:
The brittle ice zone typically returns poorer quality samples than for the rest of the core. Some steps can be taken to alleviate the problem. Liners can be placed inside the drill barrel to enclose the core before it is brought to the surface, but this makes it difficult to clean off the drilling
479:
The drill removes an annulus of ice around the core but does not cut under it. A spring-loaded lever arm called a core dog can break off the core and hold it in place while it is brought to the surface. The core is then extracted from the drill barrel, usually by laying it out flat so that the core
379:
that press against the borehole, to prevent the drill assembly rotating around the drillhead as it cuts the core. The drilling fluid is usually circulated down around the outside of the drill and back up between the core and core barrel; the cuttings are stored in the downhole assembly, in a chamber
2714:
in
Antarctica in an area where old ice lay near the surface. The cores were dated by potassium-argon dating; traditional ice core dating is not possible as not all layers were present. The oldest core was found to include ice from 2.7 million years ago—by far the oldest ice yet dated from a core.
1731:
with a high voltage between them on the surface of the ice core gives a measurement of the conductivity at that point. Dragging them down the length of the core, and recording the conductivity at each point, gives a graph that shows an annual periodicity. Such graphs also identify chemical changes
777:
Any method of counting layers eventually runs into difficulties as the flow of the ice causes the layers to become thinner and harder to see with increasing depth. The problem is more acute at locations where accumulation is high; low accumulation sites, such as central
Antarctica, must be dated by
769:
Cores show visible layers, which correspond to annual snowfall at the core site. If a pair of pits is dug in fresh snow with a thin wall between them and one of the pits is roofed over, an observer in the roofed pit will see the layers revealed by sunlight shining through. A six-foot pit may show
227:. The lowest layer of a glacier, called basal ice, is frequently formed of subglacial meltwater that has refrozen. It can be up to about 20 m thick, and though it has scientific value (for example, it may contain subglacial microbial populations), it often does not retain stratigraphic information.
4730:
Sigl, M.; Winstrup, M.; McConnell, J. R.; Welten, K. C.; Plunkett, G.; Ludlow, F.; Büntgen, U.; Caffee, M.; Chellman, N.; Dahl-Jensen, D.; Fischer, H.; Kipfstuhl, S.; Kostick, C.; Maselli, O. J.; Mekhaldi, F.; Mulvaney, R.; Muscheler, R.; Pasteris, D. R.; Pilcher, J. R.; Salzer, M.; Schüpbach, S.;
2525:
as "the father of modern snow surveying". In the winter of 1908–1909, Church constructed steel tubes with slots and cutting heads to retrieve cores of snow up to 3 m long. Similar devices are in use today, modified to allow sampling to a depth of about 9 m. They are simply pushed into
773:
In central
Greenland a typical year might produce two or three feet of winter snow, plus a few inches of summer snow. When this turns to ice, the two layers will make up no more than a foot of ice. The layers corresponding to the summer snow will contain bigger bubbles than the winter layers, so
374:
The need for a string of drillpipe that extends from the surface to the bottom of the borehole can be eliminated by suspending the entire downhole assembly on an armoured cable that conveys power to the downhole motor. These cable-suspended drills can be used for both shallow and deep holes; they
309:
time (the time taken to pull the drilling equipment out of the hole and return it to the bottom of the hole). Since retrieval of each segment of core requires tripping, a slower speed of travel through the drilling fluid could add significant time to a project—a year or more for a deep hole. The
2649:
and Vostok in the
Antarctic; not all these early holes retrieved cores. Over the following decades work continued at multiple locations in Asia. Drilling in the Antarctic focused mostly on Mirny and Vostok, with a series of deep holes at Vostok begun in 1970. The first deep hole at Vostok reached
2453:
Meteorites and micrometeorites that land on polar ice are sometimes concentrated by local environmental processes. For example, there are places in
Antarctica where winds evaporate surface ice, concentrating the solids that are left behind, including meteorites. Meltwater ponds can also contain
395:
When drilling in temperate ice, thermal drills have an advantage over electromechanical (EM) drills: ice melted by pressure can refreeze on EM drill bits, reducing cutting efficiency, and can clog other parts of the mechanism. EM drills are also more likely to fracture ice cores where the ice is
230:
Cores are often drilled in areas such as
Antarctica and central Greenland where the temperature is almost never warm enough to cause melting, but the summer sunlight can still alter the snow. In polar areas, the Sun is visible day and night during the local summer and invisible all winter. It can
484:
coring project, a vacuuming system was set up to facilitate this. The surface that receives the core should be aligned as accurately as possible with the drill barrel to minimise mechanical stress on the core, which can easily break. The ambient temperature is kept well below freezing to avoid
383:
Thermal drills, which cut ice by electrically heating the drill head, can also be used, but they have some disadvantages. Some have been designed for working in cold ice; they have high power consumption and the heat they produce can degrade the quality of the retrieved ice core. Early thermal
353:
rotated from the top, and drilling fluid is pumped down through the pipe and back up around it. The cuttings are removed from the fluid at the top of the hole and the fluid is then pumped back down. This approach requires long trip times, since the entire drill string must be hoisted out of the
1741:
in
Indonesia injected material into the stratosphere, and can be identified in both Greenland and Antarctic ice cores. If the date of the eruption is not known, but it can be identified in multiple cores, then dating the ice can in turn give a date for the eruption, which can then be used as a
2586:
project at Camp
Century, where in the early 1960s three holes were drilled, the deepest reaching the base of the ice sheet at 1387 m in July 1966. The drill used at Camp Century then went to Byrd Station, where a 2164 m hole was drilled to bedrock before the drill was frozen into the
3690:
Bazin, L.; Landais, A.; Lemieux-Dudon, B.; Toyé Mahamadou Kele, H.; Veres, D.; Parrenin, F.; Martinerie, P.; Ritz, C.; Capron, E.; Lipenkov, V.; Loutre, M.-F.; Raynaud, D.; Vinther, B.; Svensson, A.; Rasmussen, S. O.; Severi, M.; Blunier, T.; Leuenberger, M.; Fischer, H.; Masson-Delmotte, V.;
410:
Ice cores from different depths are not all equally in demand by scientific investigators, which can lead to a shortage of ice cores at certain depths. To address this, work has been done on technology to drill replicate cores: additional cores, retrieved by drilling into the sidewall of the
2569:
research around the world, with one of the high priority research targets being deep cores in polar regions. SIPRE conducted pilot drilling trials in 1956 (to 305 m) and 1957 (to 411 m) at Site 2 in
Greenland; the second core, with the benefit of the previous year's drilling experience, was
770:
anything from less than a year of snow to several years of snow, depending on the location. Poles left in the snow from year to year show the amount of accumulated snow each year, and this can be used to verify that the visible layer in a snow pit corresponds to a single year's snowfall.
493:, and stored for shipment. Additional packing, including padding material, is added. When the cores are flown from the drilling site, the aircraft's flight deck is unheated to help maintain a low temperature; when they are transported by ship they must be kept in a refrigeration unit.
2533:
Expedition to central Greenland in 1930–1931. Sorge dug a 15 m pit to examine the snow layers, and his results were later formalized into Sorge's Law of Densification by Henri Bader, who went on to do additional coring work in northwest Greenland in 1933. In the early 1950s, a
930:
354:
hole, and each length of pipe must be separately disconnected, and then reconnected when the drill string is reinserted. Along with the logistical difficulties associated with bringing heavy equipment to ice sheets, this makes traditional rotary drills unattractive. In contrast,
294:(chips of ice cut away by the drill) must be drawn up the hole and disposed of or they will reduce the cutting efficiency of the drill. They can be removed by compacting them into the walls of the hole or into the core, by air circulation (dry drilling), or by the use of a
200:, or to summer melting, and the overall shape of the glacier does not change much with time. The outward flow can distort the layers, so it is desirable to drill deep ice cores at places where there is very little flow. These can be located using maps of the flow lines.
489:
below snow level to simplify temperature maintenance, though additional refrigeration can be used. If more drilling fluid must be removed, air may be blown over the cores. Any samples needed for preliminary analysis are taken. The core is then bagged, often in
2790:
Retrieve ice cores that reach back over 1.2 million years, in order to obtain multiple iterations of ice core record for the 40,000-year long climate cycles known to have operated at that time. Current cores reach back over 800,000 years, and show 100,000-year
407:(expanded) until it is wide enough to accept the casing; a large diameter auger can also be used, avoiding the need for reaming. An alternative to casing is to use water in the borehole to saturate the porous snow and firn; the water eventually turns to ice.
2664:, a European ice coring collaboration, was formed in the 1990s, and two holes were drilled in East Antarctica: one at Dome C, which reached 2871 m in only two seasons of drilling, but which took another four years to reach bedrock at 3260 m; and one at
419:
The logistics of any coring project are complex because the locations are usually difficult to reach, and may be at high altitude. The largest projects require years of planning and years to execute, and are usually run as international consortiums. The
403:(fitted with a cylindrical lining), since otherwise the drilling fluid will be absorbed by the snow and firn. The casing has to reach down to the impermeable ice layers. To install casing a shallow auger can be used to create a pilot hole, which is then
1736:
in Iceland in 1783, can be identified in the ice core record, it provides a cross-check on the age determined by layer counting. Material from Laki can be identified in Greenland ice cores, but did not spread as far as Antarctica; the 1815 eruption of
2691:(WAIS) project, completed in 2011, reached 3405 m; the site has high snow accumulation so the ice only extends back 62,000 years, but as a consequence, the core provides high resolution data for the period it covers. A 948 m core was drilled at
785:
In addition to manual inspection and logging of features identified in a visual inspection, cores can be optically scanned so that a digital visual record is available. This requires the core to be cut lengthwise, so that a flat surface is created.
314:, for safety and to minimize the effect on the environment; it must be available at a reasonable cost; and it must be relatively easy to transport. Historically, there have been three main types of ice drilling fluids: two-component fluids based on
286:
for lowering and raising the auger, cores up to 50 m deep can be retrieved, but the practical limit is about 30 m for engine-powered augers, and less for hand augers. Below this depth, electromechanical or thermal drills are used.
2675:, which reached 2503 m in 1996, with an estimated age of 330,000 years for the bottom of the core; and a subsequent hole at the same site which reached 3035 m in 2006, estimated to reach ice 720,000 years old. US teams drilled at
1896:. Another complication is that in areas with low accumulation rates, deposition from fog can increase the concentration in the snow, sometimes to the point where the atmospheric concentration could be overestimated by a factor of two.
239:
forms on the top layer. Buried under the snow of following years, the coarse-grained hoar frost compresses into lighter layers than the winter snow. As a result, alternating bands of lighter and darker ice can be seen in an ice core.
764:
19 cm long section of GISP 2 ice core from 1855 m showing annual layer structure illuminated from below by a fibre optic source. Section contains 11 annual layers with summer layers (arrowed) sandwiched between darker winter
2668:, which reached bedrock at 2760 m in 2006. The Dome C core had very low accumulation rates, which mean that the climate record extended a long way; by the end of the project the usable data extended to 800,000 years ago.
172:
An ice core is a vertical column through a glacier, sampling the layers that formed through an annual cycle of snowfall and melt. As snow accumulates, each layer presses on lower layers, making them denser until they turn into
103:, 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.
1338:
440:, and includes representatives from 12 countries on its steering committee. Over the course of a drilling season, scores of people work at the camp, and logistics support includes airlift capabilities provided by the
689:
Timescales for ice cores from the same hemisphere can usually be synchronised using layers that include material from volcanic events. It is more difficult to connect the timescales in different hemispheres. The
1149:{\displaystyle \mathrm {\delta ^{18}O} ={\Biggl (}\mathrm {\frac {{\bigl (}{\frac {^{18}O}{^{16}O}}{\bigr )}_{sample}}{{\bigl (}{\frac {^{18}O}{^{16}O}}{\bigr )}_{SMOW}}} -1{\Biggr )}\times 1000\ ^{o}\!/\!_{oo},}
1216:
measurements of an ice core sample with the borehole temperature at the depth it came from provides additional information, in some cases leading to significant corrections to the temperatures deduced from the
2517:'s Antarctic expedition in 1902 and 1903, 30 m holes were drilled in an iceberg south of the Kerguelen Islands and temperature readings were taken. The first scientist to create a snow sampling tool was
546:
zone, bubbles of air are trapped in the ice under great pressure. When the core is brought to the surface, the bubbles can exert a stress that exceeds the tensile strength of the ice, resulting in cracks and
2786:(International Partnerships in Ice Core Sciences) has produced a series of white papers outlining future challenges and scientific goals for the ice core science community. These include plans to:
4732:
752:, "In many ways, ice cores are the 'rosetta stones' that allow development of a global network of accurately dated paleoclimatic records using the best ages determined anywhere on the planet".
2555:
453:
4938:
Arienzo, M. M.; McConnell, J. R.; Chellman, N.; Criscitiello, A. S.; Curran, M.; Fritzsche, D.; Kipfstuhl, S.; Mulvaney, R.; Nolan, M.; Opel, T.; Sigl, M.; Steffensen, J.P. (5 July 2016).
4443:
Bauska, Thomas K.; Baggenstos, Daniel; Brook, Edward J.; Mix, Alan C.; Marcott, Shaun A.; Petrenko, Vasilii V.; Schaefer, Hinrich; Severinghaus, Jeffrey P.; Lee, James E. (29 March 2016).
45:. 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
1346:
showed that the deuterium excess reflects the temperature, relative humidity, and wind speed of the ocean where the moisture originated. Since then it has been customary to measure both.
56:
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
2547:
1224:
data. Not all boreholes can be used in these analyses. If the site has experienced significant melting in the past, the borehole will no longer preserve an accurate temperature record.
686:
components of dust. The very small quantities typically found require at least 300 g of ice to be used, limiting the ability of the technique to precisely assign an age to core depths.
4367:
1719:
Summer snow in Greenland contains some sea salt, blown from the surrounding waters; there is less of it in winter, when much of the sea surface is covered by pack ice. Similarly,
654:
can be isolated by subliming the ice in a vacuum, keeping the temperature low enough to avoid the loess giving up any carbon. The results have to be corrected for the presence of
2538:
expedition took pit samples over much of the Greenland ice sheet, obtaining early oxygen isotope ratio data. Three other expeditions in the 1950s began ice coring work: a joint
1875:
Some of the deposited chemical species may interact with the ice, so what is detected in an ice core is not necessarily what was originally deposited. Examples include HCHO and
551:. At greater depths, the air disappears into clathrates and the ice becomes stable again. At the WAIS Divide site, the brittle ice zone was from 520 m to 1340 m depth.
4044:"Formal definition and dating of the GSSP (Global Stratotype Section and Point) for the base of the Holocene using the Greenland NGRIP ice core, and selected auxiliary records"
196:
Two or three feet of snow may turn into less than a foot of ice. The weight above makes deeper layers of ice thin and flow outwards. Ice is lost at the edges of the glacier to
2823:
is found to create glacial meltwater that washes away temporally ordered layers of trapped aerosols that researchers use as an historical record of environmental events. The
5764:
Landais, A.; Dreyfus, G.; Capron, E.; Pol, K.; Loutre, M.F.; Raynaud, D.; Lipenkov, V.Y.; Arnaud, L.; Masson-Delmotte, V.; Paillard, D.; Jouzel, J.; Leuenberger, M. (2012).
899:
is slightly more likely to condense from vapour into rain or snow crystals. At lower temperatures, the difference is more pronounced. The standard method of recording the
3135:
425:
730:
techniques to find the optimal combination of multiple independent records. This approach was developed in 2010 and has since been turned into a software tool, DatIce.
1831:) is produced in the atmosphere by marine organisms, so ice core records of MSA provide information on the history of the oceanic environment. Both hydrogen peroxide (
266:
and they are still used for short holes. A design for ice core augers was patented in 1932 and they have changed little since. An auger is essentially a cylinder with
2470:
In addition to the impurities in a core and the isotopic composition of the water, the physical properties of the ice are examined. Features such as crystal size and
5475:
298:(wet drilling). Dry drilling is limited to about 400 m depth, since below that point a hole would close up as the ice deforms from the weight of the ice above.
5973:
1753:
levels in Greenland ice had increased by a factor of over 200 since pre-industrial times, and increases in other elements produced by industrial processes, such as
1723:
appears only in summer snow because its production in the atmosphere requires sunlight. These seasonal changes can be detected because they lead to changes in the
411:
borehole, at depths of particular interest. Replicate cores were successfully retrieved at WAIS divide in the 2012–2013 drilling season, at four different depths.
2747:. EastGRIP reopened for field work in 2022, where the CryoEgg reached new depths in the ice, under pressures in excess of 200 bar and temperatures of around -30c.
1680:, have been used to infer the thickness of the firn layer, and determine other palaeoclimatic information such as past mean ocean temperatures. Some gases such as
4042:; Cwynar, Les C.; Hughen, Konrad; Kershaw, Peter; Kromer, Bernd; Litt, Thomas; Lowe, David J.; Nakagawa, Takeshi; Newnham, Rewi; Schwander, Jakob (January 2009).
3654:
2743:, which began in 2015 in east Greenland and was planned to be completed in 2020. In March 2020, the 2020 EGRIP field campaign was cancelled due to the ongoing
2474:
orientation can reveal the history of ice flow patterns in the ice sheet. The crystal size can also be used to determine dates, though only in shallow cores.
1684:
can rapidly diffuse through ice, so it may be necessary to test for these "fugitive gases" within minutes of the core being retrieved to obtain accurate data.
1391:. Combining this information with records of carbon dioxide levels, also obtained from ice cores, provides information about the mechanisms behind changes in
262:
Ice cores are collected by cutting around a cylinder of ice in a way that enables it to be brought to the surface. Early cores were often collected with hand
5603:
4631:
Martinerie, P.; Nourtier-Mazauric, E.; Barnola, J.-M.; Sturges, W. T.; Worton, D. R.; Atlas, E.; Gohar, L. K.; Shine, K. P.; Brasseur, G. P. (17 June 2009).
2406:
have been found in ice cores in Antarctica and Greenland. Chlorine-36, which has a half-life of 301,000 years, has been used to date cores, as have krypton (
4866:"High-resolution records of the beryllium-10 solar activity proxy in ice from Law Dome, East Antarctica: measurement, reproducibility and principal trends"
1342:
where d is the deuterium excess. It was once thought that this meant it was unnecessary to measure both ratios in a given core, but in 1979 Merlivat and
1283:
2603:
5005:
203:
Impurities in the ice provide information on the environment from when they were deposited. These include soot, ash, and other types of particle from
4603:
4038:
Walker, Mike; Johnsen, Sigfus; Rasmussen, Sune Olander; Popp, Trevor; Steffensen, Jørgen-Peder; Gibbard, Phil; Hoek, Wim; Lowe, John; Andrews, John;
76:
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
2739:) project retrieved a 2537 m core in 2010 from a site further north, extending the climatic record to 128,500 years ago; NEEM was followed by
794:
The isotopic composition of the oxygen in a core can be used to model the temperature history of the ice sheet. Oxygen has three stable isotopes,
596:
which gases are trapped for a given location, but their predictions have not always proved reliable. At locations with very low snowfall, such as
4092:
2582:, the following year. The success of the IGY core drilling led to increased interest in improving ice coring capabilities, and was followed by a
5389:
2539:
4004:
6016:
5811:
667:
produced directly in the ice by cosmic rays, and the amount of correction depends strongly on the location of the ice core. Corrections for
543:
4371:
6606:
6282:
6011:
5711:
3826:
Uglietti, Chiara; Zapf, Alexander; Jenk, Theo Manuel; Sigl, Michael; Szidat, Sönke; Salazar, Gary; Schwikowski, Margit (21 December 2016).
2595:
290:
The cutting apparatus of a drill is on the bottom end of a drill barrel, the tube that surrounds the core as the drill cuts downward. The
4540:
5565:
4539:
Schilt, Adrian; Baumgartner, Matthias; Blunierc, Thomas; Schwander, Jakob; Spahni, Renato; Fischer, Hubertus; Stocker, Thomas F. (2009).
270:
metal ribs (known as flights) wrapped around the outside, at the lower end of which are cutting blades. Hand augers can be rotated by a
185:
in Antarctica the depth is 95 m and the age 2500 years. As further layers build up, the pressure increases, and at about 1500 m the
1439:, but it was not until the late 1970s that a reliable extraction method was developed. Early results included a demonstration that the
122:, with the deepest core reaching 3769 m. Numerous other deep cores in the Antarctic have been completed over the years, including the
53:(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.
83:
Impurities in ice cores may depend on location. Coastal areas are more likely to include material of marine origin, such as sea salt
500:
in the US. These locations make samples available for testing. A substantial fraction of each core is archived for future analyses.
3002:
5834:
4541:"Glacial-interglacial and millennial-scale variations in the atmospheric nitrous oxide concentration during the last 800,000 years"
2812:
Come up with a standardised lightweight drill capable of drilling both wet and dry holes, and able to reach depths of up to 1000 m.
363:
is flexible enough to be coiled when at the surface. This eliminates the need to disconnect and reconnect the pipes during a trip.
5476:"Surviving Harsh Operating Conditions: How Protronix EMS is Powering Cutting-Edge Research in East Greenland | Protronix EMS"
1635:, a record of the summer insolation, and hence combining this data with orbital cycle data establishes an ice core dating scheme.
5043:
3139:
2783:
569:
2800:
Drill additional cores to provide high-resolution data for the last 2,000 years, to use as input for detailed climate modelling.
2340:
in the atmosphere at a rate that depends on the solar magnetic field. The strength of the field is related to the intensity of
2462:, an important component of sediment cores, can also be found in ice cores. It provides information on changes in vegetation.
1527:(nitrous oxide) levels are also correlated with glacial cycles, though at low temperatures the graph differs somewhat from the
5070:"An ice-core pollen record showing vegetation response to Late-glacial and Holocene climate changes at Nevado Sajama, Bolivia"
5955:
5883:
5630:
4615:
3667:
3311:
3043:
2985:
2942:
6053:
4633:"Long-lived halocarbon trends and budgets from atmospheric chemistry modelling constrained with measurements in polar firn"
1732:
caused by non-seasonal events such as forest fires and major volcanic eruptions. When a known volcanic event, such as the
456:, a previous Greenland ice core drilling site, to the EastGRIP site. Drilling is expected to continue until at least 2020.
2865:
714:) can be used to connect the chronology of a Greenland core (for example) with an Antarctic core. In cases where volcanic
3511:
2374:
in ice cores, about 10,000 atoms in a gram of ice, and these can be used to provide long-term records of solar activity.
476:
With some variation between projects, the following steps must occur between drilling and final storage of the ice core.
301:
Drilling fluids are chosen to balance the pressure so that the hole remains stable. The fluid must have a low kinematic
235:, leaving the top inch or so less dense. When the Sun approaches its lowest point in the sky, the temperature drops and
6910:
6400:
3034:
Gabrielli, Paolo; Vallelonga, Paul (2015). "Contaminant Records in Ice Cores". In Blais, Jules M.; et al. (eds.).
2483:
6601:
6197:
3953:
3782:
3673:
2797:
Identify additional proxies from ice cores, for example for sea ice, marine biological productivity, or forest fires.
748:
The dating of ice sheets has proved to be a key element in providing dates for palaeoclimatic records. According to
1455:
than just before the start of the industrial age. Further research has demonstrated a reliable correlation between
7515:
6237:
2732:
1700:, can be detected in ice cores after about 1950; almost all CFCs in the atmosphere were created by human activity.
1611:
correlates with the strength of local summer insolation. This means that the trapped air retains, in the ratio of
1435:
It was understood in the 1960s that analyzing the air trapped in ice cores would provide useful information on the
5595:
3867:
349:
Rotary drilling is the main method of drilling for minerals and it has also been used for ice drilling. It uses a
5103:"Physical properties of the P96 ice core from Penny Ice Cap, Baffin Island, Canada, and derived climatic records"
2740:
421:
139:
5428:
7165:
2562:
232:
107:
1575:(oxygen) can be used to date ice cores: as air is gradually trapped by the snow turning to firn and then ice,
189:
of the ice changes from hexagonal to cubic, allowing air molecules to move into the cubic crystals and form a
6647:
6395:
4939:
4905:
Wagenhach, D.; Graf, W.; Minikin, A.; Trefzer, U.; Kipfstuhl, J.; Oerter, H.; Blindow, N. (20 January 2017).
2513:; these were drilled with iron rods and did not produce cores. The deepest hole achieved was 60 m. On
2360:
480:
can slide out onto a prepared surface. The core must be cleaned of drilling fluid as it is slid out; for the
5712:"Field season 2016: East GReenland Ice core Project (EGRIP) 2015–2020: Establishing the EGRIP drilling camp"
5009:
106:
Ice cores have been studied since the early 20th century, and several cores were drilled as a result of the
6390:
3396:
1358:
497:
7536:
7145:
6580:
6450:
4502:
2724:
2389:), created by nuclear weapons testing in the 1950s and 1960s, has been identified in ice cores, and both
734:
449:
135:
6021:
4394:
3439:
2763:. Some of these cores reach back to the last glacial period, but they are more important as records of
2558:, in central Greenland. Core quality was poor, but some scientific work was done on the retrieved ice.
698:
about 40,000 years ago, can be identified in cores; away from that point, measurements of gases such as
568:
Many different kinds of analysis are performed on ice cores, including visual layer counting, tests for
7084:
6790:
6770:
5765:
4445:"Carbon isotopes characterize rapid changes in atmospheric carbon dioxide during the last deglaciation"
2728:
778:
other methods. For example, at Vostok, layer counting is only possible down to an age of 55,000 years.
469:
110:(1957–1958). Depths of over 400 m were reached, a record which was extended in the 1960s to 2164 m at
4245:
4191:
4096:
3693:"An optimized multi-proxy, multi-site Antarctic ice and gas orbital chronology (AICC2012): 120–800 ka"
1365:, followed by slower cooling. Other isotopic ratios have been studied, for example, the ratio between
6780:
6752:
6585:
6364:
3036:
Environmental Contaminants: Using Natural Archives to Track Sources and Long-Term Trends of Pollution
2570:
retrieved in much better condition, with fewer gaps. In Antarctica, a 307 m core was drilled at
2375:
922:
3482:
513:
7120:
6847:
6046:
4013:
2696:
2688:
1749:
Many other elements and molecules have been detected in ice cores. In 1969, it was discovered that
433:
127:
123:
5822:
3304:
Exploration of Antarctic Subglacial Aquatic Environments: Environmental and Scientific Stewardship
3271:"Thermal electric ice-core drills: history and new design options for intermediate-depth drilling"
258:
Ice auger patented in 1932; the design is very similar to modern augers used for shallow drilling.
254:
7170:
6785:
6735:
6522:
6369:
6026:
2866:"Coronavirus Already Hindering Climate Science, But the Worst Disruptions Are Likely Yet to Come"
1724:
1420:
445:
100:
5718:
5454:
3359:
Anonymous (30 June 2017), Ice Drilling Design and Operations: Long Range Technology Plan, p. 24.
7430:
7079:
6903:
6685:
6486:
6232:
6131:
5710:
Dahl-Jensen, Dorthe; Kirk, Marie; Larsen, Lars.B.; Sheldon, Simon G.; Steffensen, J.P. (2016).
4563:
3868:"An extremely brief reversal of the geomagnetic field, climate variability and a super volcano"
2590:
French, Australian and Canadian projects from the 1960s and 1970s include a 905 m core at
719:
5675:
Blunier, T.; Spahni, R.; Barnola, J.-M.; Chappellaz, J.; Loulergue, L.; Schwander, J. (2007).
5569:
4907:"Reconnaissance of chemical and isotopic firn properties on top of Berkner Island, Antarctica"
4287:
3161:
Sheldon, Simon G.; Popp, Trevor J.; Hansen, Steffen B.; Steffensen, Jørgen P. (26 July 2017).
7453:
7160:
6287:
3970:
2824:
723:
142:, originally expected to complete a deep core in east Greenland in 2020 but since postponed.
95:
that correlate with cold, dry periods in the past, when cold deserts were scoured by wind.
68:
trapped in tiny bubbles can be analysed to determine the level of atmospheric gases such as
7196:
6720:
6661:
6637:
6632:
5924:
5846:
5788:
5742:
5688:
5653:
5338:
5114:
4954:
4877:
4744:
4689:
4644:
4456:
4206:
4055:
3839:
3798:
3704:
3569:
2806:
Improve the ability to handle brittle ice, both while drilling and in transport and storage
2529:
The first systematic study of snow and firn layers was by Ernst Sorge, who was part of the
2326:
1452:
727:
695:
429:
338:. Newer fluids have been proposed, including new ester-based fluids, low-molecular weight
8:
7546:
7390:
7217:
7135:
6747:
6642:
6560:
6550:
6325:
6242:
6222:
6212:
6039:
3163:"Promising new borehole liquids for ice-core drilling on the East Antarctic high plateau"
3009:
2514:
1499:
600:, the uncertainty in the difference between ages of ice and gas can be over 1,000 years.
65:
5928:
5850:
5792:
5746:
5692:
5657:
5342:
5118:
4958:
4881:
4748:
4648:
4460:
4210:
4059:
3843:
3802:
3783:"AMS radiocarbon dating of ice: validity of the technique and the problem of cosmogenic
3708:
3573:
3558:"International ice core community meets to discuss best practices for ice core curation"
2977:
2971:
2775:, in the Alps, and in Indonesia, New Zealand, Iceland, Scandinavia, Canada, and the US.
525:
7541:
7222:
7019:
6872:
6852:
6730:
6715:
6700:
6622:
6421:
6385:
6187:
5862:
5036:
4978:
4768:
4479:
4444:
4073:
2455:
1685:
1159:
607:
441:
424:
project, for example, which as of 2017 is drilling in eastern Greenland, is run by the
355:
151:
7317:
5042:(Report). Cold Regions Research and Engineering Lab, Hanover, NH. pp. 1–2. 97–1.
4218:
3327:
Schwikowski, Margit; Jenk, Theo M.; Stampfli, Dieter; Stampfli, Felix (26 July 2017).
3001:
Tulaczyk, S.; Elliot, D.; Vogel, S.W.; Powell, R.D.; Priscu, J.C.; Clow, G.D. (2002).
2815:
Improve core handling to maximise the information that can be obtained from each core.
2687:(1004 m in 1999), with both cores reaching ice from the last glacial period. The
7505:
7468:
7292:
7009:
6896:
6680:
6476:
6471:
6315:
6151:
5951:
5898:
5879:
5626:
4982:
4970:
4760:
4611:
4484:
3949:
3828:"Radiocarbon dating of glacier ice: overview, optimisation, validation and potential"
3663:
3307:
3039:
2981:
2938:
2840:
2772:
2744:
2506:
1833:
1720:
1689:
683:
585:
400:
186:
5866:
4559:
4260:
4077:
3617:
Uchida, Tsutomu; Duval, P.; Lipenkov, V.Ya.; Hondoh, T.; Mae, S.; Shoji, H. (1994).
7510:
7410:
7307:
7237:
7099:
6978:
6877:
6826:
6742:
6690:
6466:
6444:
6310:
6207:
5932:
5854:
5796:
5750:
5696:
5661:
5346:
5122:
5081:
4962:
4918:
4885:
4772:
4752:
4685:
4652:
4555:
4474:
4464:
4256:
4214:
4063:
3847:
3806:
3722:
3712:
3577:
3340:
3301:
3282:
3174:
2794:
Improve ice core chronologies, including connecting chronologies of multiple cores.
2634:
2575:
2177:
1495:
742:
581:
577:
343:
339:
61:
5101:
Okuyama, Junichi; Narita, Hideki; Hondoh, Takeo; Koerner, Roy M. (February 2003).
4039:
2699:
from 2002 to 2005, extending into the last glacial period; and an Italian-managed
1333:{\displaystyle \mathrm {\delta D} =8\times \mathrm {\delta ^{18}O} +\mathrm {d} ,}
134:. In Greenland, a sequence of collaborative projects began in the 1970s with the
7405:
7380:
7262:
7175:
7064:
6810:
6775:
6762:
6725:
6672:
6530:
6425:
6359:
6320:
6157:
4246:"Recent melt rates of Canadian arctic ice caps are the highest in four millennia"
3138:. Niels Bohr Institute Centre for Ice and Climate. 2 October 2008. Archived from
2676:
2543:
2518:
2356:
2341:
2315:
2046:
1693:
1436:
622:. In the polar ice sheets there is about 15–20 μg of carbon in the form of
366:
335:
323:
306:
156:
1864:
that are linked to vegetation emissions and forest fires. Some species, such as
7347:
7297:
7282:
7155:
7140:
7069:
7054:
6988:
6973:
6710:
6508:
6496:
6440:
6435:
6429:
6354:
6277:
6202:
5966:
5666:
5641:
5390:"Record-shattering 2.7-million-year-old ice core reveals start of the ice ages"
5351:
5326:
5008:. US Geological Survey Central Region Research. 14 January 2005. Archived from
4923:
4906:
4449:
Proceedings of the National Academy of Sciences of the United States of America
2820:
2768:
2692:
2665:
2579:
2530:
691:
597:
496:
There are several locations around the world that store ice cores, such as the
295:
291:
279:
220:
119:
69:
6006:
5996:
5967:
Fifty Years of Soviet and Russian Drilling Activity in Polar and Non-Polar Ice
3811:
3515:
760:
7530:
7478:
7420:
7400:
7395:
7342:
7337:
7322:
7267:
7150:
7125:
7004:
6627:
6545:
6540:
6491:
6481:
6121:
6001:
5997:
US National Ice Core Laboratory video showing storage and processing of cores
5902:
4940:"A Method for Continuous Pu Determinations in Arctic and Antarctic Ice Cores"
2755:
Ice cores have been drilled at locations away from the poles, notably in the
2646:
2642:
2607:
2522:
2502:
2395:
1781:
1738:
1643:
749:
389:
263:
96:
77:
73:
50:
7212:
4966:
4657:
4632:
4469:
3852:
3827:
3689:
3003:
FASTDRILL: Interdisciplinary Polar Research Based on Fast Ice-Sheet Drilling
2493:
678:
produced by nuclear testing have much less impact on the results. Carbon in
7358:
7287:
7044:
7039:
6983:
6705:
6503:
6217:
6192:
6177:
6143:
6103:
5755:
5730:
5035:
Taylor, Susan; Lever, James H.; Harvey, Ralph P.; Govoni, John (May 1997).
4974:
4764:
4733:"Timing and climate forcing of volcanic eruptions for the past 2,500 years"
4488:
3717:
3692:
2845:
2630:
2571:
2471:
1861:
1856:
1697:
1388:
1362:
1350:
1253:) and makes water more likely to condense and less likely to evaporate. A
679:
573:
360:
350:
319:
275:
249:
212:
161:
115:
111:
46:
5937:
5912:
5801:
5701:
5676:
5327:"Drilling to the beds of the Greenland and Antarctic ice sheets: a review"
5086:
5069:
4890:
4865:
3345:
3328:
3287:
3270:
3179:
3162:
2618:
7473:
7352:
7332:
7327:
7312:
7272:
7130:
7014:
6405:
6302:
6264:
6247:
6182:
6163:
6096:
6076:
5127:
5102:
4630:
3582:
3557:
2711:
2680:
2626:
levels (ppm) going back nearly 800,000 years, and related glacial cycles.
2390:
2129:
1767:
1733:
1343:
481:
399:
When drilling deep holes, which require drilling fluid, the hole must be
376:
178:
138:; there have been multiple follow-up projects, with the most recent, the
34:
5367:
4756:
1703:
Greenland cores, during times of climatic transition, may show excess CO
580:. For the results of these tests to be useful in the reconstruction of
7500:
7483:
7463:
7415:
7049:
6963:
6172:
6167:
6062:
3727:
3329:"A new thermal drilling system for high-altitude or temperate glaciers"
2704:
2684:
2566:
2434:
2408:
2133:
1803:
1514:
can be used to determine the relationship between core depth and age.
572:
and physical properties, and assays for inclusion of gases, particles,
385:
310:
fluid must contaminate the ice as little as possible; it must have low
236:
216:
5858:
4672:
Delmas, Robert J. (1993). "A natural artefact in Greenland ice-core CO
2764:
1427:
7089:
7029:
6958:
6953:
6948:
6862:
6842:
6575:
6535:
6272:
6081:
6012:
A misleading graph has been circling the internet since at least 2010
6007:
Byrd Polar Research Center – Ice Core Paleoclimatology Research Group
5432:
4068:
4043:
3618:
2828:
2756:
2736:
2653:
1765:, have also been recorded. The presence of nitric and sulfuric acid (
1743:
1728:
1638:
1228:
1227:
Hydrogen ratios can also be used to calculate a temperature history.
822:
809:
796:
655:
635:
592:
490:
302:
190:
88:
38:
4937:
1411:
519:
Bubbles in an Antarctic ice sample. Illuminated with polarised light
7443:
7438:
7115:
7024:
6857:
6339:
6252:
5913:"Core handling and processing for the WAIS Divide ice-core project"
2599:
2421:
2319:
1869:
1807:
738:
315:
311:
271:
204:
197:
7252:
5766:"Towards orbital dating of the EPICA Dome C ice core using δO
4731:
Steffensen, J. P.; Vinther, B. M.; Woodruff, T. E. (8 July 2015).
4538:
2809:
Find a way to handle cores which have pressurised water at bedrock
1802:) in precipitation can be shown to correlate with increasing fuel
1486:, the amount in the atmosphere is correlated with the strength of
1419:(green), reconstructed temperature (blue) and dust (red) from the
888:
is slightly more likely to turn into vapour, and water containing
7385:
7375:
7302:
7074:
7059:
6968:
6943:
6919:
6867:
6091:
6086:
3971:"Toward a radiometric ice clock: U-series of the Dome C ice core"
3944:
Elias, Scott; Mock, Cary, eds. (2013). "Volcanic Tephra Layers".
1865:
1758:
1673:
1491:
1487:
1483:
726:
has also been used to date ice cores. Another approach is to use
711:
437:
404:
327:
208:
181:
in Greenland, the depth is 77 m and the ice is 230 years old; at
57:
42:
3404:
682:
can also be dated by separating and testing the water-insoluble
604:
firn density to calculate the temperature when the firn formed.
7257:
6938:
6933:
3326:
2672:
2591:
2551:
2459:
1754:
1681:
1646:
processes in trapped air, determined by the measurement of the
745:
information that can be correlated with other climate proxies.
715:
283:
224:
182:
118:
ice drilling projects in Antarctica include decades of work at
4370:. Centre for Ice and Climate. 8 September 2009. Archived from
346:, and kerosene-based fluids mixed with foam-expansion agents.
193:. The bubbles disappear and the ice becomes more transparent.
7448:
7277:
7094:
6292:
6031:
5717:. Ice and Climate Group, Niels Bohr Institute. Archived from
3447:
2760:
2700:
2661:
2638:
2583:
2535:
1677:
1467:
levels and the temperature calculated from ice isotope data.
1354:
639:
548:
532:
531:
Sliver of Antarctic ice showing trapped bubbles. Images from
331:
267:
131:
92:
5709:
5596:"The race to save glacial ice records before they melt away"
4012:. EGU General Assembly 2012. Vienna, Austria. Archived from
3619:"Brittle zone and air-hydrate formation in polar ice sheets"
3468:
3425:
3302:
National Research Council of the National Academies (2007).
3008:(Report). 2002 FASTDRILL Workshop. p. 9. Archived from
2723:
In 1970, scientific discussions began which resulted in the
1254:
21:
7458:
7227:
7034:
6888:
6226:
6108:
5677:"Synchronization of ice core records via atmospheric gases"
4904:
4729:
3306:. Washington DC: National Academies Press. pp. 82–84.
3160:
2935:
Paleoclimatology: Reconstructing Climates of the Quaternary
2510:
1762:
1750:
1669:
452:. In 2015 the EastGRIP team moved the camp facilities from
174:
165:
5100:
4037:
2671:
Other deep Antarctic cores included a Japanese project at
1860:) have been studied, along with organic molecules such as
464:
322:
to increase density; alcohol compounds, including aqueous
6126:
5731:"A brief history of ice core science over the last 50 yr"
5037:
Collecting micrometeorites from the South Pole Water Well
4006:
Toward unified ice core chronologies with the DatIce tool
3616:
3000:
2831:
in Antarctica in advance of this impending loss of data.
1502:, for which a timescale is available from other sources,
84:
4442:
4395:"How are past temperatures determined from an ice core?"
5763:
5068:
Reese, C.A.; Liu, K.B.; Thompson, L.G. (26 July 2017).
5034:
4587:
3931:
3904:
3370:
2587:
borehole by sub-ice meltwater and had to be abandoned.
5897:. Washington DC: World Data Center A for Glaciology .
5642:"Reliability of ice-core science: historical insights"
4003:
Toyé Mahamadou Kele, H.; et al. (22 April 2012).
921:
ratio is to subtract the ratio in a standard known as
855:
indicates the temperature when the snow fell. Because
5625:. Princeton, New Jersey: Princeton University Press.
1286:
933:
5965:
Ueda, Herbert T.; Talalay, Pavel G. (October 2007).
4610:. Cambridge: Cambridge University Press. p. 9.
4505:. National Weather Service Climate Prediction Center
3825:
1490:, which are in turn correlated with the strength of
1357:
in Greenland, were instrumental in the discovery of
145:
6607:
Global Boundary Stratotype Section and Point (GSSP)
5589:
5587:
4002:
3033:
722:and hence provide fixed points for dating the ice.
132:
International Trans-Antarctic Scientific Expedition
3662:. Chichester: John Wiley & Sons. p. 150.
3268:
1387:can provide information about past changes in the
1332:
1148:
591:A difficulty in ice core dating is that gases can
5431:. East Greenland Ice Core Project. Archived from
5308:
5306:
5304:
5302:
5289:
5287:
5285:
5224:
5222:
4823:
4821:
4784:
4782:
4713:
4711:
3204:
3202:
3118:
3116:
3088:
3086:
3084:
3082:
3069:
3067:
3038:. Dordrecht, Netherlands: Springer. p. 395.
2610:cores recovered by a Canadian team in the 1970s.
1133:
1126:
1105:
954:
99:elements, either of natural origin or created by
7528:
5584:
5067:
4522:
4520:
4503:"Climate Prediction Center – Expert Assessments"
4414:
4412:
4338:
4336:
4190:Ruddiman, William F.; Raymo, Maureen E. (2003).
4170:
4168:
4166:
4164:
4162:
4160:
4158:
4156:
4154:
3600:
3598:
3596:
3594:
3539:
3537:
3535:
3533:
3371:"EastGrip – The East Greenland Ice-core Project"
2916:
2914:
718:is interspersed with ice, it can be dated using
5832:
4851:
4839:
4827:
4812:
4800:
4788:
4717:
3927:
3925:
3623:Memoirs of National Institute of Polar Research
3269:Zagorodnov, V.; Thompson, L.G. (26 July 2017).
3103:
3101:
2771:in south Asia. Cores have also been drilled on
2606:, starting in 1969 with a 382 m core; and
634:in each kilogram of ice, and there may also be
5835:"Glaciochemistry of polar ice cores: A review"
5674:
5299:
5282:
5219:
4818:
4779:
4708:
4598:
4596:
3916:
3892:
3514:. National Ice Core Laboratory. Archived from
3199:
3113:
3079:
3064:
2884:
2882:
2657:The EPICA Dome C and Vostok ice cores compared
2540:Norwegian-British-Swedish Antarctic Expedition
1711:production by acidic and alkaline impurities.
1349:Water isotope records, analyzed in cores from
6904:
6047:
5909:
5568:. PAGES – Past Global Changes. Archived from
4517:
4409:
4333:
4273:
4189:
4151:
3780:
3764:
3762:
3604:
3591:
3543:
3530:
2911:
2633:ice drilling projects began in the 1950s, in
2322:from 1960s nuclear testing in US glacier ice.
1406:
1074:
1034:
1004:
964:
5325:Bentley, Charles R.; Koci, Bruce R. (2007).
5107:Journal of Geophysical Research: Solid Earth
4311:
4309:
4307:
4305:
3922:
3512:"About Ice Cores :: Drilling Ice Cores"
3098:
2901:
2899:
2897:
370:Mechanical drill head, showing cutting teeth
16:Cylindrical sample drilled from an ice sheet
5964:
5324:
5276:
5264:
5252:
5240:
4593:
4192:"A methane-based time scale for Vostok ice"
4185:
4183:
3691:Chappellaz, J.; Wolff, E. (1 August 2013).
2976:. Cheltenham, UK: Stanley Thornes. p.
2879:
6911:
6897:
6054:
6040:
5873:
4315:
3990:
3759:
3136:"Deep drilling with the Hans Tausen drill"
2937:. Amsterdam: Academic Press. p. 138.
282:to power the rotation. With the aid of a
168:between surface snow and blue glacier ice.
5936:
5892:
5878:(3rd ed.). Abingdon, UK: Routledge.
5800:
5754:
5700:
5665:
5552:
5540:
5528:
5516:
5504:
5492:
5350:
5126:
5085:
4922:
4889:
4656:
4478:
4468:
4302:
4067:
3969:Aciego, S.; et al. (15 April 2010).
3943:
3851:
3810:
3726:
3716:
3581:
3344:
3286:
3178:
2894:
1267:. There is a linear relationship between
6602:Global Standard Stratigraphic Age (GSSA)
5427:Madsen, Martin Vindbæk (15 March 2016).
4392:
4288:"Periodic Table of Elements: O – Oxygen"
4180:
3437:
3395:Madsen, Martin Vindbæk (14 April 2016).
3368:
2703:project completed a 1620 m core at
2652:
2617:
2613:
2492:
2314:
1431:Ozone-depleting gases in Greenland firn.
1426:
1410:
1260:ratio can be defined in the same way as
759:
463:
414:
365:
253:
164:in Alaska. There is increasingly dense
155:
20:
5945:
5809:
5414:
5213:
5201:
5189:
5177:
5165:
5153:
5141:
3640:
3555:
3480:
3256:
3244:
3232:
3220:
3208:
3193:
3122:
3107:
3092:
3073:
2932:
2920:
2718:
2710:In 2016, cores were retrieved from the
2574:in 1957–1958, and a 264 m core at
2419:, with a half-life of 11 years), lead (
1707:in air bubbles when analysed, due to CO
375:require an anti-torque device, such as
278:, and some can be attached to handheld
80:that best fits all the available data.
7529:
5876:Reconstructing Quaternary Environments
5812:"The history of early polar ice cores"
5728:
5426:
5312:
5293:
5228:
4947:Environmental Science & Technology
4690:10.1034/j.1600-0889.1993.t01-3-00006.x
4671:
4602:
4526:
4430:
4418:
4393:Mulvaney, Robert (20 September 2004).
4342:
4243:
4231:
4174:
3968:
3753:
3741:
3652:
3505:
3503:
3481:Kolbert, Elizabeth (24 October 2016).
3394:
2969:
2863:
2465:
1900:Soluble impurities found in ice cores
6892:
6035:
5893:MacKinnon, P.K. (1980). "Ice Cores".
5639:
5620:
5593:
5365:
5022:
4863:
4702:
4354:
4327:
4285:
4145:
4133:
4121:
4109:
3768:
3438:Petersen, Sandra (23 February 2016).
3369:Petersen, Sandra (23 February 2016).
3058:
2957:
2905:
2888:
2857:
1551:graphs. Similarly, the ratio between
610:can be used on the carbon in trapped
5874:Lowe, J. John; Walker, Mike (2014).
5810:Langway, Chester C. (January 2008).
5049:from the original on 11 October 2017
3781:Wilson, A.T.; Donahue, D.J. (1992).
2053:Human and biological gas emissions:
1191:of 0‰; a sample that is depleted in
789:
4608:Climate Change and Climate Modeling
4253:Global and Planetary Climate Change
4090:
3874:. ScienceX network. 16 October 2012
3500:
2803:Identify an improved drilling fluid
2448:
1482:(methane) is produced in lakes and
13:
6401:Adoption of the Gregorian calendar
5976:from the original on 20 April 2017
5948:Mechanical Ice Drilling Technology
5833:Legrand, M.; Mayewski, P. (1997).
5606:from the original on 16 July 2024.
4995:Delmas et al. (2004), pp. 494–496.
3946:Encyclopedia of Quaternary Science
2750:
2484:History of scientific ice drilling
1714:
1451:concentration was 30% less at the
1361:—rapid warming at the onset of an
1323:
1315:
1291:
1242:, or D) is heavier than hydrogen (
1089:
1086:
1083:
1080:
1065:
1051:
1025:
1022:
1019:
1016:
1013:
1010:
995:
981:
945:
755:
459:
126:project, and cores managed by the
37:that is typically removed from an
14:
7558:
5990:
4637:Atmospheric Chemistry and Physics
4368:"Isotopes and the delta notation"
3556:Hinkley, Todd (9 December 2003).
2548:Juneau Ice Field Research Project
146:Structure of ice sheets and cores
7516:Template:Periglacial environment
5972:(Report). ERDC/CRREL. TR-07-02.
5558:
5546:
5534:
5522:
5510:
5498:
5486:
5468:
5447:
5420:
5408:
5382:
5359:
5318:
5270:
5258:
5246:
5234:
5207:
5195:
5183:
5171:
5159:
5147:
5135:
5094:
4091:Gow, Anthony (12 October 2001).
2310:
1688:(CFCs), which contribute to the
638:particles from wind-blown dust (
558:
542:Over a depth range known as the
524:
512:
25:Ice core sample taken from drill
6283:English and British regnal year
6022:Beyond EPICA-Oldest Ice mission
5821:(TR-08-1): 1–47. Archived from
5368:"TALos Dome Ice CorE – TALDICE"
5061:
5028:
5016:
4998:
4989:
4931:
4898:
4857:
4845:
4833:
4806:
4794:
4723:
4696:
4665:
4624:
4581:
4560:10.1016/j.quascirev.2009.03.011
4532:
4495:
4436:
4424:
4386:
4360:
4348:
4321:
4279:
4267:
4261:10.1016/j.gloplacha.2011.06.005
4237:
4225:
4139:
4127:
4115:
4103:
4093:"Summer and winter core layers"
4084:
4031:
3996:
3984:
3962:
3937:
3910:
3898:
3886:
3860:
3819:
3774:
3747:
3735:
3683:
3646:
3634:
3610:
3549:
3509:
3474:
3462:
3444:East Greenland Ice Core Project
3431:
3419:
3401:East Greenland Ice Core Project
3388:
3375:East Greenland Ice Core Project
3362:
3353:
3320:
3295:
3262:
3250:
3238:
3226:
3214:
3187:
3154:
3128:
3052:
2778:
2556:Expéditions Polaires Françaises
1642:the bottom of a column. These
1498:. Since insolation depends on
140:East Greenland Ice-Core Project
6061:
5594:Jones, Nicola (14 July 2024).
3787:production in polar ice cores"
3027:
2994:
2963:
2951:
2926:
2563:International Geophysical Year
2526:the snow and rotated by hand.
2488:
503:
108:International Geophysical Year
1:
6396:Old Style and New Style dates
4219:10.1016/S0277-3791(02)00082-3
4048:Journal of Quaternary Science
3978:TALDICE-EPICA Science Meeting
2864:Berwyn, Bob (27 March 2020).
2851:
2622:Composite data for Dome C, CO
2363:can detect the low levels of
2361:Accelerator mass spectrometry
1599:, and the relative amount of
6918:
6348:Pre-Julian / Julian
4290:. EnvironmentalChemistry.com
2933:Bradley, Raymond S. (2015).
2695:by a project managed by the
498:National Ice Core Laboratory
91:ice cores contain layers of
7:
6581:Geological history of Earth
6451:Astronomical year numbering
6017:A 2.7 million year old core
4852:Legrand & Mayewski 1997
4840:Legrand & Mayewski 1997
4828:Legrand & Mayewski 1997
4813:Legrand & Mayewski 1997
4801:Legrand & Mayewski 1997
4789:Legrand & Mayewski 1997
4718:Legrand & Mayewski 1997
2834:
2725:Greenland Ice Sheet Project
1158:where the ‰ sign indicates
450:National Science Foundation
136:Greenland Ice Sheet Project
10:
7563:
5946:Talalay, Pavel G. (2016).
5667:10.3189/002214311796406130
5640:Alley, Richard B. (2010).
5621:Alley, Richard B. (2000).
5613:
5455:"Finally, put in at EGRIP"
5352:10.3189/172756407786857695
4924:10.3189/172756494794587401
4548:Quaternary Science Reviews
4199:Quaternary Science Reviews
2827:plans to store additional
2594:in Antarctica, drilled by
2565:(1957–1958) saw increased
2481:
2477:
2432:, 22 years), and silicon (
2304:, other organic compounds
1423:for the past 420,000 years
1407:Palaeoatmospheric sampling
426:Centre for Ice and Climate
318:-like products mixed with
247:
149:
60:provide information about
7496:
7429:
7368:
7245:
7236:
7205:
7184:
7108:
6997:
6926:
6835:
6819:
6803:
6761:
6753:Thermoluminescence dating
6671:
6660:
6648:Samarium–neodymium dating
6615:
6594:
6568:
6559:
6521:
6459:
6414:
6378:
6347:
6338:
6301:
6263:
6142:
6117:
6069:
5623:The Two-Mile Time Machine
3812:10.1017/S0033822200063657
3656:Quaternary Dating Methods
2970:Knight, Peter G. (1999).
2683:(554 m in 1994) and
1727:of the ice. Placing two
1587:is lost more easily than
1359:Dansgaard-Oeschger events
1162:. A sample with the same
923:standard mean ocean water
733:The boundary between the
563:
446:Hercules transport planes
243:
6467:Chinese sexagenary cycle
2697:British Antarctic Survey
2689:West Antarctic Ice Sheet
1746:about 72,000 years ago.
576:, and various molecular
434:University of Copenhagen
160:Sampling the surface of
128:British Antarctic Survey
124:West Antarctic Ice Sheet
6681:Amino acid racemisation
5277:Ueda & Talalay 2007
5265:Ueda & Talalay 2007
5253:Ueda & Talalay 2007
5241:Ueda & Talalay 2007
4967:10.1021/acs.est.6b01108
4658:10.5194/acp-9-3911-2009
4470:10.1073/pnas.1513868113
3948:. Amsterdam: Elsevier.
3853:10.5194/tc-10-3091-2016
3469:Dahl-Jensen et al. 2016
3426:Dahl-Jensen et al. 2016
2497:A store of core samples
2355:in the atmosphere is a
2138:Atmospheric chemistry:
1725:electrical conductivity
570:electrical conductivity
6686:Archaeomagnetic dating
6198:Era of Caesar (Iberia)
5756:10.5194/cp-9-2525-2013
5396:. AAAS. 14 August 2017
4316:Lowe & Walker 2014
4286:Barbalace, Kenneth L.
4244:Fisher, David (2011).
4095:. NOAA. Archived from
3991:Lowe & Walker 2014
3718:10.5194/cp-9-1715-2013
3483:"When a Country Melts"
2658:
2627:
2498:
2323:
1911:Measured in polar ice
1432:
1424:
1334:
1150:
766:
473:
371:
259:
169:
26:
7454:Giant current ripples
6586:Geological time units
5950:. Beijing: Springer.
5938:10.3189/2014AoG68A008
5839:Reviews of Geophysics
5802:10.5194/cp-8-191-2012
5702:10.5194/cp-3-325-2007
5646:Journal of Glaciology
5370:. Talos Dome Ice Core
5087:10.3189/2013AoG63A375
5012:on 13 September 2005.
4891:10.5194/cp-7-707-2011
4397:. Scientific American
3653:Walker, Mike (2005).
3346:10.3189/2014AoG68A024
3288:10.3189/2014AoG68A012
3180:10.3189/2014AoG68A043
2825:Ice Memory Foundation
2679:in the 1990s, and at
2656:
2621:
2614:Antarctica deep cores
2505:drilled holes in the
2496:
2318:
1430:
1414:
1335:
1151:
763:
467:
442:US Air National Guard
415:Large coring projects
369:
257:
159:
24:
6638:Law of superposition
6633:Isotope geochemistry
5917:Annals of Glaciology
5911:(31 December 2014).
5828:on 18 November 2016.
5566:"IPICS White Papers"
5331:Annals of Glaciology
5128:10.1029/2001JB001707
5074:Annals of Glaciology
4911:Annals of Glaciology
4864:Pedro, J.B. (2011).
4099:on 13 February 2010.
3583:10.1029/2003EO490006
3333:Annals of Glaciology
3275:Annals of Glaciology
3167:Annals of Glaciology
2719:Greenland deep cores
2454:meteorites. At the
2327:Galactic cosmic rays
1854:) and formaldehyde (
1453:last glacial maximum
1284:
1184:ratio as SMOW has a
931:
833:. The ratio between
728:Bayesian probability
696:geomagnetic reversal
430:Niels Bohr Institute
351:string of drill pipe
62:ancient temperatures
7391:Moraine-dammed lake
7218:Subglacial eruption
6771:Fluorine absorption
6748:Luminescence dating
6643:Luminescence dating
6551:Milankovitch cycles
6391:Proleptic Gregorian
6223:Hindu units of time
5929:2014AnGla..55...15S
5851:1997RvGeo..35..219L
5793:2012CliPa...8..191L
5781:Climate of the Past
5747:2013CliPa...9.2525J
5735:Climate of the Past
5729:Jouzel, J. (2013).
5693:2007CliPa...3..325B
5681:Climate of the Past
5658:2010JGlac..56.1095A
5343:2007AnGla..47....1B
5119:2003JGRB..108.2090O
4959:2016EnST...50.7066A
4882:2011CliPa...7..707P
4870:Climate of the Past
4757:10.1038/nature14565
4749:2015Natur.523..543S
4649:2009ACP.....9.3911M
4588:Landais et al. 2012
4461:2016PNAS..113.3465B
4211:2003QSRv...22..141R
4060:2009JQS....24....3W
4019:on 5 September 2017
3932:Landais et al. 2012
3917:Blunier et al. 2007
3905:Landais et al. 2012
3893:Blunier et al. 2007
3844:2016TCry...10.3091U
3803:1992Radcb..34..431W
3709:2013CliPa...9.1715B
3697:Climate of the Past
3574:2003EOSTr..84..549H
3142:on 3 September 2017
3015:on 4 September 2017
2546:in Antarctica; the
2515:Erich von Drygalski
2466:Physical properties
1999:Terrestrial salts:
1901:
1686:Chlorofluorocarbons
877:, water containing
396:under high stress.
211:; isotopes such as
41:or a high mountain
7537:Incremental dating
7223:Subglacial volcano
7206:Volcanic relations
6873:Terminus post quem
6853:Synchronoptic view
6820:Linguistic methods
6781:Obsidian hydration
6716:Radiometric dating
6701:Incremental dating
6623:Chronostratigraphy
5895:Glaciological Data
5652:(200): 1095–1103.
5572:on 11 October 2017
4274:Souney et al. 2014
3605:Souney et al. 2014
3544:Souney et al. 2014
2659:
2628:
2501:In 1841 and 1842,
2499:
2456:South Pole Station
2344:, so the level of
2324:
1899:
1433:
1425:
1330:
1160:parts per thousand
1146:
767:
720:argon/argon dating
608:Radiocarbon dating
586:orbital parameters
582:palaeoenvironments
474:
372:
260:
170:
152:Ice-sheet dynamics
27:
7524:
7523:
7492:
7491:
7010:Accumulation zone
6886:
6885:
6799:
6798:
6656:
6655:
6517:
6516:
6472:Geologic Calendar
6334:
6333:
5957:978-7-116-09172-6
5885:978-0-415-74075-3
5859:10.1029/96RG03527
5632:978-0-691-10296-2
5366:Iaccarino, Tony.
4953:(13): 7066–7073.
4743:(7562): 543–549.
4643:(12): 3911–3934.
4617:978-0-521-84157-3
4455:(13): 3465–3470.
3669:978-0-470-86927-7
3510:UNH, Joe Souney.
3313:978-0-309-10635-1
3045:978-94-017-9540-1
2987:978-0-7487-4000-0
2944:978-0-12-386913-5
2841:List of ice cores
2773:Mount Kilimanjaro
2745:COVID-19 pandemic
2507:Unteraargletscher
2308:
2307:
1996:Aridity and wind
1721:hydrogen peroxide
1690:greenhouse effect
1119:
1095:
1069:
999:
790:Isotopic analysis
344:fatty-acid esters
340:dimethyl siloxane
187:crystal structure
7554:
7411:Terminal moraine
7243:
7242:
6979:Piedmont glacier
6913:
6906:
6899:
6890:
6889:
6878:ASPRO chronology
6827:Glottochronology
6743:Tephrochronology
6691:Dendrochronology
6669:
6668:
6566:
6565:
6365:Proleptic Julian
6355:Pre-Julian Roman
6345:
6344:
6140:
6139:
6056:
6049:
6042:
6033:
6032:
6002:Ice Core Gateway
5985:
5983:
5981:
5971:
5961:
5942:
5940:
5906:
5889:
5870:
5829:
5827:
5816:
5806:
5804:
5778:
5760:
5758:
5741:(6): 2525–2547.
5725:
5724:on 9 April 2017.
5723:
5716:
5706:
5704:
5671:
5669:
5636:
5608:
5607:
5591:
5582:
5581:
5579:
5577:
5562:
5556:
5550:
5544:
5538:
5532:
5526:
5520:
5514:
5508:
5502:
5496:
5490:
5484:
5483:
5480:protronix.co.uk/
5472:
5466:
5465:
5463:
5461:
5451:
5445:
5444:
5442:
5440:
5435:on 18 March 2017
5424:
5418:
5412:
5406:
5405:
5403:
5401:
5386:
5380:
5379:
5377:
5375:
5363:
5357:
5356:
5354:
5322:
5316:
5310:
5297:
5291:
5280:
5274:
5268:
5262:
5256:
5250:
5244:
5238:
5232:
5226:
5217:
5211:
5205:
5199:
5193:
5187:
5181:
5175:
5169:
5163:
5157:
5151:
5145:
5139:
5133:
5132:
5130:
5098:
5092:
5091:
5089:
5065:
5059:
5058:
5056:
5054:
5048:
5041:
5032:
5026:
5020:
5014:
5013:
5002:
4996:
4993:
4987:
4986:
4944:
4935:
4929:
4928:
4926:
4902:
4896:
4895:
4893:
4861:
4855:
4849:
4843:
4837:
4831:
4825:
4816:
4810:
4804:
4798:
4792:
4786:
4777:
4776:
4727:
4721:
4715:
4706:
4700:
4694:
4693:
4669:
4663:
4662:
4660:
4628:
4622:
4621:
4604:Neelin, J. David
4600:
4591:
4585:
4579:
4578:
4576:
4574:
4569:on 8 August 2017
4568:
4562:. Archived from
4554:(1–2): 182–192.
4545:
4536:
4530:
4524:
4515:
4514:
4512:
4510:
4499:
4493:
4492:
4482:
4472:
4440:
4434:
4428:
4422:
4421:, pp. 2533–2534.
4416:
4407:
4406:
4404:
4402:
4390:
4384:
4383:
4381:
4379:
4364:
4358:
4352:
4346:
4340:
4331:
4325:
4319:
4313:
4300:
4299:
4297:
4295:
4283:
4277:
4271:
4265:
4264:
4250:
4241:
4235:
4229:
4223:
4222:
4196:
4187:
4178:
4172:
4149:
4143:
4137:
4131:
4125:
4119:
4113:
4107:
4101:
4100:
4088:
4082:
4081:
4071:
4069:10.1002/jqs.1227
4035:
4029:
4028:
4026:
4024:
4018:
4011:
4000:
3994:
3988:
3982:
3981:
3975:
3966:
3960:
3959:
3941:
3935:
3929:
3920:
3914:
3908:
3902:
3896:
3890:
3884:
3883:
3881:
3879:
3864:
3858:
3857:
3855:
3838:(6): 3091–3105.
3823:
3817:
3816:
3814:
3778:
3772:
3766:
3757:
3751:
3745:
3744:, pp. 2530–2531.
3739:
3733:
3732:
3730:
3720:
3703:(4): 1715–1731.
3687:
3681:
3680:
3679:on 14 July 2014.
3678:
3672:. Archived from
3661:
3650:
3644:
3638:
3632:
3630:
3614:
3608:
3602:
3589:
3587:
3585:
3553:
3547:
3541:
3528:
3527:
3525:
3523:
3507:
3498:
3497:
3495:
3493:
3478:
3472:
3466:
3460:
3459:
3457:
3455:
3446:. Archived from
3440:"About EastGRIP"
3435:
3429:
3423:
3417:
3416:
3414:
3412:
3403:. Archived from
3392:
3386:
3385:
3383:
3381:
3366:
3360:
3357:
3351:
3350:
3348:
3324:
3318:
3317:
3299:
3293:
3292:
3290:
3266:
3260:
3254:
3248:
3242:
3236:
3230:
3224:
3218:
3212:
3206:
3197:
3191:
3185:
3184:
3182:
3158:
3152:
3151:
3149:
3147:
3132:
3126:
3120:
3111:
3105:
3096:
3090:
3077:
3071:
3062:
3056:
3050:
3049:
3031:
3025:
3024:
3022:
3020:
3014:
3007:
2998:
2992:
2991:
2967:
2961:
2955:
2949:
2948:
2930:
2924:
2918:
2909:
2903:
2892:
2886:
2877:
2876:
2874:
2872:
2861:
2635:Franz Josef Land
2576:Little America V
2449:Other inclusions
2444:
2441:
2440:
2431:
2428:
2427:
2418:
2415:
2414:
2405:
2402:
2401:
2388:
2386:
2385:
2373:
2371:
2370:
2354:
2352:
2351:
2339:
2337:
2336:
2303:
2302:
2301:
2292:
2291:
2290:
2281:
2280:
2279:
2271:
2270:
2260:
2259:
2258:
2248:
2247:
2246:
2236:
2235:
2234:
2225:
2224:
2223:
2213:
2212:
2211:
2200:
2199:
2198:
2188:
2186:
2185:
2174:
2170:
2169:
2168:
2160:
2159:
2149:
2148:
2147:
2127:
2126:
2125:
2115:
2114:
2113:
2103:
2099:
2097:
2096:
2086:
2084:
2083:
2075:
2074:
2064:
2063:
2062:
2047:aluminosilicates
2044:
2043:
2042:
2032:
2031:
2030:
2020:
2019:
2018:
2009:
2008:
2007:
1988:
1987:
1986:
1977:
1976:
1975:
1965:
1964:
1963:
1954:
1953:
1952:
1943:
1942:
1941:
1932:
1931:
1930:
1902:
1898:
1895:
1894:
1893:
1885:
1884:
1859:
1853:
1851:
1850:
1842:
1841:
1830:
1829:
1828:
1820:
1819:
1808:Methanesulfonate
1801:
1799:
1798:
1790:
1789:
1778:
1776:
1775:
1734:eruption of Laki
1667:
1665:
1664:
1656:
1654:
1653:
1634:
1633:
1632:
1622:
1621:
1620:
1610:
1609:
1608:
1598:
1597:
1596:
1586:
1585:
1584:
1574:
1573:
1572:
1562:
1561:
1560:
1550:
1549:
1548:
1538:
1537:
1536:
1526:
1524:
1523:
1513:
1512:
1511:
1481:
1480:
1479:
1466:
1465:
1464:
1450:
1449:
1448:
1402:
1401:
1400:
1386:
1384:
1383:
1375:
1373:
1372:
1339:
1337:
1336:
1331:
1326:
1318:
1314:
1313:
1294:
1277:
1270:
1263:
1257:
1252:
1250:
1249:
1241:
1239:
1238:
1220:
1212:
1209:. Combining the
1205:
1201:
1199:
1198:
1187:
1183:
1181:
1180:
1172:
1170:
1169:
1155:
1153:
1152:
1147:
1142:
1141:
1131:
1125:
1124:
1117:
1109:
1108:
1096:
1094:
1093:
1092:
1078:
1077:
1070:
1068:
1064:
1063:
1054:
1050:
1049:
1040:
1038:
1037:
1030:
1029:
1028:
1008:
1007:
1000:
998:
994:
993:
984:
980:
979:
970:
968:
967:
960:
958:
957:
948:
944:
943:
920:
918:
917:
909:
907:
906:
898:
896:
895:
887:
885:
884:
876:
874:
873:
866:is lighter than
865:
863:
862:
854:
852:
851:
843:
841:
840:
832:
829:
828:
819:
816:
815:
806:
803:
802:
709:
708:
707:
677:
675:
674:
665:
663:
662:
653:
652:
651:
633:
632:
631:
621:
620:
619:
528:
516:
114:in Antarctica.
7562:
7561:
7557:
7556:
7555:
7553:
7552:
7551:
7527:
7526:
7525:
7520:
7488:
7425:
7406:Sevetti moraine
7364:
7318:Roche moutonnée
7263:Cirque stairway
7232:
7201:
7180:
7104:
7065:Lateral moraine
6993:
6922:
6917:
6887:
6882:
6831:
6815:
6811:Molecular clock
6804:Genetic methods
6795:
6776:Nitrogen dating
6763:Relative dating
6757:
6726:Potassium–argon
6673:Absolute dating
6663:
6652:
6611:
6590:
6555:
6531:Cosmic Calendar
6523:Astronomic time
6513:
6455:
6410:
6374:
6360:Original Julian
6330:
6297:
6259:
6158:Ab urbe condita
6136:
6113:
6065:
6060:
5993:
5988:
5979:
5977:
5969:
5958:
5886:
5825:
5814:
5776:
5773:
5769:
5721:
5714:
5633:
5616:
5611:
5600:Popular Science
5592:
5585:
5575:
5573:
5564:
5563:
5559:
5551:
5547:
5539:
5535:
5527:
5523:
5515:
5511:
5503:
5499:
5491:
5487:
5474:
5473:
5469:
5459:
5457:
5453:
5452:
5448:
5438:
5436:
5429:"Documentation"
5425:
5421:
5413:
5409:
5399:
5397:
5388:
5387:
5383:
5373:
5371:
5364:
5360:
5323:
5319:
5311:
5300:
5292:
5283:
5275:
5271:
5263:
5259:
5251:
5247:
5239:
5235:
5227:
5220:
5212:
5208:
5200:
5196:
5188:
5184:
5176:
5172:
5164:
5160:
5152:
5148:
5140:
5136:
5113:(B2): 6–1–6–2.
5099:
5095:
5066:
5062:
5052:
5050:
5046:
5039:
5033:
5029:
5021:
5017:
5004:
5003:
4999:
4994:
4990:
4942:
4936:
4932:
4903:
4899:
4862:
4858:
4850:
4846:
4838:
4834:
4826:
4819:
4811:
4807:
4799:
4795:
4787:
4780:
4728:
4724:
4720:, pp. 222, 225.
4716:
4709:
4701:
4697:
4676:measurements".
4675:
4670:
4666:
4629:
4625:
4618:
4601:
4594:
4586:
4582:
4572:
4570:
4566:
4543:
4537:
4533:
4525:
4518:
4508:
4506:
4501:
4500:
4496:
4441:
4437:
4429:
4425:
4417:
4410:
4400:
4398:
4391:
4387:
4377:
4375:
4374:on 10 July 2017
4366:
4365:
4361:
4353:
4349:
4341:
4334:
4326:
4322:
4314:
4303:
4293:
4291:
4284:
4280:
4272:
4268:
4248:
4242:
4238:
4230:
4226:
4194:
4188:
4181:
4173:
4152:
4144:
4140:
4132:
4128:
4120:
4116:
4108:
4104:
4089:
4085:
4036:
4032:
4022:
4020:
4016:
4009:
4001:
3997:
3989:
3985:
3973:
3967:
3963:
3956:
3942:
3938:
3930:
3923:
3915:
3911:
3903:
3899:
3891:
3887:
3877:
3875:
3866:
3865:
3861:
3824:
3820:
3779:
3775:
3767:
3760:
3752:
3748:
3740:
3736:
3688:
3684:
3676:
3670:
3659:
3651:
3647:
3639:
3635:
3615:
3611:
3603:
3592:
3554:
3550:
3542:
3531:
3521:
3519:
3508:
3501:
3491:
3489:
3479:
3475:
3467:
3463:
3453:
3451:
3450:on 28 June 2017
3436:
3432:
3424:
3420:
3410:
3408:
3407:on 28 June 2017
3393:
3389:
3379:
3377:
3367:
3363:
3358:
3354:
3339:(68): 131–136.
3325:
3321:
3314:
3300:
3296:
3281:(68): 322–330.
3267:
3263:
3255:
3251:
3243:
3239:
3231:
3227:
3219:
3215:
3207:
3200:
3192:
3188:
3173:(68): 260–270.
3159:
3155:
3145:
3143:
3134:
3133:
3129:
3121:
3114:
3106:
3099:
3091:
3080:
3072:
3065:
3057:
3053:
3046:
3032:
3028:
3018:
3016:
3012:
3005:
2999:
2995:
2988:
2968:
2964:
2956:
2952:
2945:
2931:
2927:
2919:
2912:
2904:
2895:
2887:
2880:
2870:
2868:
2862:
2858:
2854:
2837:
2821:warming climate
2781:
2769:monsoon seasons
2753:
2751:Non-polar cores
2721:
2677:McMurdo Station
2625:
2616:
2544:Queen Maud Land
2521:, described by
2519:James E. Church
2491:
2486:
2480:
2468:
2451:
2439:
2437:
2436:
2435:
2433:
2426:
2424:
2423:
2422:
2420:
2413:
2411:
2410:
2409:
2407:
2400:
2398:
2397:
2396:
2394:
2384:
2382:
2381:
2380:
2379:
2369:
2367:
2366:
2365:
2364:
2350:
2348:
2347:
2346:
2345:
2342:solar radiation
2335:
2333:
2332:
2331:
2330:
2313:
2300:
2298:
2297:
2296:
2294:
2289:
2287:
2286:
2285:
2283:
2278:
2275:
2274:
2273:
2269:
2266:
2265:
2264:
2262:
2257:
2254:
2253:
2252:
2250:
2245:
2242:
2241:
2240:
2238:
2233:
2231:
2230:
2229:
2227:
2222:
2219:
2218:
2217:
2215:
2210:
2208:
2207:
2206:
2204:
2197:
2194:
2193:
2192:
2190:
2184:
2181:
2180:
2179:
2176:
2172:
2167:
2164:
2163:
2162:
2158:
2155:
2154:
2153:
2151:
2146:
2143:
2142:
2141:
2139:
2124:
2121:
2120:
2119:
2117:
2112:
2109:
2108:
2107:
2105:
2101:
2095:
2092:
2091:
2090:
2088:
2082:
2079:
2078:
2077:
2073:
2070:
2069:
2068:
2066:
2061:
2058:
2057:
2056:
2054:
2041:
2038:
2037:
2036:
2034:
2029:
2026:
2025:
2024:
2022:
2017:
2015:
2014:
2013:
2011:
2006:
2004:
2003:
2002:
2000:
1985:
1983:
1982:
1981:
1979:
1974:
1971:
1970:
1969:
1967:
1962:
1960:
1959:
1958:
1956:
1951:
1949:
1948:
1947:
1945:
1940:
1938:
1937:
1936:
1934:
1929:
1927:
1926:
1925:
1923:
1919:Waves and wind
1892:
1889:
1888:
1887:
1883:
1880:
1879:
1878:
1876:
1855:
1849:
1846:
1845:
1844:
1840:
1837:
1836:
1835:
1832:
1827:
1824:
1823:
1822:
1818:
1815:
1814:
1813:
1811:
1797:
1794:
1793:
1792:
1788:
1785:
1784:
1783:
1780:
1774:
1771:
1770:
1769:
1766:
1717:
1715:Glaciochemistry
1710:
1706:
1692:and also cause
1663:
1661:
1660:
1659:
1658:
1652:
1650:
1649:
1648:
1647:
1631:
1628:
1627:
1626:
1624:
1619:
1616:
1615:
1614:
1612:
1607:
1604:
1603:
1602:
1600:
1595:
1592:
1591:
1590:
1588:
1583:
1580:
1579:
1578:
1576:
1571:
1568:
1567:
1566:
1564:
1563:(nitrogen) and
1559:
1556:
1555:
1554:
1552:
1547:
1544:
1543:
1542:
1540:
1535:
1532:
1531:
1530:
1528:
1522:
1519:
1518:
1517:
1515:
1510:
1507:
1506:
1505:
1503:
1478:
1475:
1474:
1473:
1471:
1463:
1460:
1459:
1458:
1456:
1447:
1444:
1443:
1442:
1440:
1437:paleoatmosphere
1421:Vostok ice core
1418:
1409:
1399:
1396:
1395:
1394:
1392:
1382:
1380:
1379:
1378:
1377:
1371:
1369:
1368:
1367:
1366:
1322:
1309:
1305:
1304:
1287:
1285:
1282:
1281:
1275:
1273:
1268:
1266:
1261:
1255:
1248:
1246:
1245:
1244:
1243:
1237:
1235:
1234:
1233:
1232:
1223:
1218:
1215:
1210:
1208:
1203:
1202:has a negative
1197:
1195:
1194:
1193:
1192:
1190:
1185:
1179:
1177:
1176:
1175:
1174:
1168:
1166:
1165:
1164:
1163:
1134:
1132:
1127:
1120:
1116:
1104:
1103:
1079:
1073:
1072:
1071:
1059:
1056:
1055:
1045:
1042:
1041:
1039:
1033:
1032:
1031:
1009:
1003:
1002:
1001:
989:
986:
985:
975:
972:
971:
969:
963:
962:
961:
959:
953:
952:
939:
935:
934:
932:
929:
928:
916:
914:
913:
912:
911:
905:
903:
902:
901:
900:
894:
892:
891:
890:
889:
883:
881:
880:
879:
878:
872:
870:
869:
868:
867:
861:
859:
858:
857:
856:
850:
848:
847:
846:
845:
839:
837:
836:
835:
834:
827:
825:
824:
823:
821:
814:
812:
811:
810:
808:
801:
799:
798:
797:
795:
792:
758:
756:Visual analysis
706:
703:
702:
701:
699:
673:
671:
670:
669:
668:
661:
659:
658:
657:
656:
650:
647:
646:
645:
643:
630:
627:
626:
625:
623:
618:
615:
614:
613:
611:
566:
561:
540:
539:
538:
537:
536:
529:
521:
520:
517:
506:
485:thermal shock.
462:
460:Core processing
417:
336:n-butyl acetate
330:solutions; and
324:ethylene glycol
280:electric drills
252:
246:
231:make some snow
221:micrometeorites
154:
148:
101:nuclear testing
93:wind-blown dust
17:
12:
11:
5:
7560:
7550:
7549:
7544:
7539:
7522:
7521:
7519:
7518:
7513:
7508:
7503:
7497:
7494:
7493:
7490:
7489:
7487:
7486:
7481:
7476:
7471:
7466:
7461:
7456:
7451:
7446:
7441:
7435:
7433:
7427:
7426:
7424:
7423:
7418:
7413:
7408:
7403:
7398:
7393:
7388:
7383:
7378:
7372:
7370:
7366:
7365:
7363:
7362:
7355:
7350:
7345:
7340:
7335:
7330:
7325:
7320:
7315:
7310:
7305:
7300:
7298:Hanging valley
7295:
7293:Glacial striae
7290:
7285:
7280:
7275:
7270:
7265:
7260:
7255:
7249:
7247:
7240:
7234:
7233:
7231:
7230:
7225:
7220:
7215:
7209:
7207:
7203:
7202:
7200:
7199:
7194:
7188:
7186:
7182:
7181:
7179:
7178:
7173:
7168:
7163:
7158:
7156:Periglaciation
7153:
7148:
7146:Outburst flood
7143:
7138:
7133:
7128:
7123:
7118:
7112:
7110:
7106:
7105:
7103:
7102:
7097:
7092:
7087:
7082:
7077:
7072:
7070:Medial moraine
7067:
7062:
7057:
7055:Glacier tongue
7052:
7047:
7042:
7037:
7032:
7027:
7022:
7017:
7012:
7007:
7001:
6999:
6995:
6994:
6992:
6991:
6989:Valley glacier
6986:
6981:
6976:
6974:Outlet glacier
6971:
6966:
6961:
6956:
6951:
6946:
6941:
6936:
6930:
6928:
6924:
6923:
6916:
6915:
6908:
6901:
6893:
6884:
6883:
6881:
6880:
6875:
6870:
6865:
6860:
6855:
6850:
6848:New Chronology
6845:
6839:
6837:
6836:Related topics
6833:
6832:
6830:
6829:
6823:
6821:
6817:
6816:
6814:
6813:
6807:
6805:
6801:
6800:
6797:
6796:
6794:
6793:
6788:
6783:
6778:
6773:
6767:
6765:
6759:
6758:
6756:
6755:
6750:
6745:
6740:
6739:
6738:
6733:
6728:
6723:
6713:
6711:Paleomagnetism
6708:
6703:
6698:
6693:
6688:
6683:
6677:
6675:
6666:
6658:
6657:
6654:
6653:
6651:
6650:
6645:
6640:
6635:
6630:
6625:
6619:
6617:
6613:
6612:
6610:
6609:
6604:
6598:
6596:
6592:
6591:
6589:
6588:
6583:
6578:
6572:
6570:
6563:
6557:
6556:
6554:
6553:
6548:
6543:
6538:
6533:
6527:
6525:
6519:
6518:
6515:
6514:
6512:
6511:
6509:New Earth Time
6506:
6501:
6500:
6499:
6494:
6484:
6479:
6474:
6469:
6463:
6461:
6457:
6456:
6454:
6453:
6448:
6438:
6433:
6418:
6416:
6412:
6411:
6409:
6408:
6403:
6398:
6393:
6388:
6382:
6380:
6376:
6375:
6373:
6372:
6370:Revised Julian
6367:
6362:
6357:
6351:
6349:
6342:
6336:
6335:
6332:
6331:
6329:
6328:
6323:
6318:
6313:
6307:
6305:
6299:
6298:
6296:
6295:
6290:
6288:Lists of kings
6285:
6280:
6278:Canon of Kings
6275:
6269:
6267:
6261:
6260:
6258:
6257:
6256:
6255:
6250:
6245:
6240:
6230:
6220:
6215:
6210:
6205:
6203:Before present
6200:
6195:
6190:
6185:
6180:
6175:
6170:
6161:
6154:
6148:
6146:
6137:
6135:
6134:
6129:
6124:
6118:
6115:
6114:
6112:
6111:
6106:
6101:
6100:
6099:
6089:
6084:
6079:
6073:
6071:
6067:
6066:
6059:
6058:
6051:
6044:
6036:
6030:
6029:
6027:Third Pole ice
6024:
6019:
6014:
6009:
6004:
5999:
5992:
5991:External links
5989:
5987:
5986:
5962:
5956:
5943:
5907:
5890:
5884:
5871:
5845:(3): 219–243.
5830:
5807:
5787:(1): 191–203.
5771:
5767:
5761:
5726:
5707:
5687:(2): 325–330.
5672:
5637:
5631:
5617:
5615:
5612:
5610:
5609:
5583:
5557:
5553:MacKinnon 1980
5545:
5541:MacKinnon 1980
5533:
5529:MacKinnon 1980
5521:
5517:MacKinnon 1980
5509:
5505:MacKinnon 1980
5497:
5493:MacKinnon 1980
5485:
5467:
5446:
5419:
5407:
5381:
5358:
5317:
5298:
5281:
5269:
5257:
5245:
5233:
5218:
5206:
5194:
5182:
5170:
5158:
5146:
5134:
5093:
5060:
5027:
5015:
4997:
4988:
4930:
4897:
4876:(3): 707–708.
4856:
4844:
4842:, pp. 227–228.
4832:
4817:
4805:
4803:, pp. 231–232.
4793:
4778:
4722:
4707:
4695:
4684:(4): 391–396.
4673:
4664:
4623:
4616:
4592:
4580:
4531:
4516:
4494:
4435:
4423:
4408:
4385:
4359:
4347:
4332:
4320:
4318:, pp. 165–170.
4301:
4278:
4266:
4255:. 84–85: 1–4.
4236:
4224:
4205:(2): 141–155.
4179:
4150:
4138:
4126:
4114:
4102:
4083:
4040:Björck, Svante
4030:
3995:
3983:
3961:
3954:
3936:
3921:
3919:, pp. 325–327.
3909:
3907:, pp. 191–192.
3897:
3885:
3859:
3832:The Cryosphere
3818:
3797:(3): 431–435.
3773:
3758:
3746:
3734:
3682:
3668:
3645:
3643:, pp. 265–266.
3633:
3609:
3590:
3548:
3529:
3499:
3487:The New Yorker
3473:
3461:
3430:
3418:
3387:
3361:
3352:
3319:
3312:
3294:
3261:
3259:, pp. 252–254.
3249:
3247:, pp. 173–175.
3237:
3235:, pp. 109–111.
3225:
3213:
3198:
3196:, pp. 259–263.
3186:
3153:
3127:
3112:
3097:
3078:
3063:
3051:
3044:
3026:
2993:
2986:
2962:
2950:
2943:
2925:
2910:
2893:
2878:
2855:
2853:
2850:
2849:
2848:
2843:
2836:
2833:
2817:
2816:
2813:
2810:
2807:
2804:
2801:
2798:
2795:
2792:
2780:
2777:
2767:events and of
2752:
2749:
2720:
2717:
2693:Berkner Island
2666:Kohnen Station
2623:
2615:
2612:
2580:Ross Ice Shelf
2531:Alfred Wegener
2490:
2487:
2479:
2476:
2467:
2464:
2450:
2447:
2445:, 172 years).
2438:
2425:
2412:
2399:
2383:
2368:
2359:for climate.
2349:
2334:
2312:
2309:
2306:
2305:
2299:
2288:
2276:
2267:
2255:
2243:
2232:
2220:
2209:
2202:
2195:
2182:
2165:
2156:
2144:
2136:
2122:
2110:
2093:
2080:
2071:
2059:
2050:
2049:
2039:
2027:
2016:
2005:
1997:
1994:
1990:
1989:
1984:
1972:
1961:
1950:
1939:
1928:
1920:
1917:
1913:
1912:
1909:
1906:
1890:
1881:
1847:
1838:
1825:
1816:
1795:
1786:
1772:
1716:
1713:
1708:
1704:
1662:
1651:
1629:
1617:
1605:
1593:
1581:
1569:
1557:
1545:
1533:
1520:
1508:
1500:orbital cycles
1476:
1461:
1445:
1416:
1408:
1405:
1397:
1381:
1370:
1329:
1325:
1321:
1317:
1312:
1308:
1303:
1300:
1297:
1293:
1290:
1272:
1265:
1247:
1236:
1222:
1214:
1207:
1196:
1189:
1178:
1167:
1145:
1140:
1137:
1130:
1123:
1115:
1112:
1107:
1102:
1099:
1091:
1088:
1085:
1082:
1076:
1067:
1062:
1058:
1053:
1048:
1044:
1036:
1027:
1024:
1021:
1018:
1015:
1012:
1006:
997:
992:
988:
983:
978:
974:
966:
956:
951:
947:
942:
938:
915:
904:
893:
882:
871:
860:
849:
838:
826:
813:
800:
791:
788:
757:
754:
743:palaeoclimatic
704:
692:Laschamp event
672:
660:
648:
628:
616:
565:
562:
560:
557:
530:
523:
522:
518:
511:
510:
509:
508:
507:
505:
502:
461:
458:
416:
413:
296:drilling fluid
245:
242:
147:
144:
120:Vostok Station
70:carbon dioxide
15:
9:
6:
4:
3:
2:
7559:
7548:
7545:
7543:
7540:
7538:
7535:
7534:
7532:
7517:
7514:
7512:
7509:
7507:
7504:
7502:
7499:
7498:
7495:
7485:
7482:
7480:
7477:
7475:
7472:
7470:
7467:
7465:
7462:
7460:
7457:
7455:
7452:
7450:
7447:
7445:
7442:
7440:
7437:
7436:
7434:
7432:
7431:Glaciofluvial
7428:
7422:
7421:Veiki moraine
7419:
7417:
7414:
7412:
7409:
7407:
7404:
7402:
7401:Rogen moraine
7399:
7397:
7396:Pulju moraine
7394:
7392:
7389:
7387:
7384:
7382:
7381:Erratic block
7379:
7377:
7374:
7373:
7371:
7367:
7361:
7360:
7356:
7354:
7351:
7349:
7346:
7344:
7343:Tunnel valley
7341:
7339:
7338:Trough valley
7336:
7334:
7331:
7329:
7326:
7324:
7321:
7319:
7316:
7314:
7311:
7309:
7306:
7304:
7301:
7299:
7296:
7294:
7291:
7289:
7286:
7284:
7281:
7279:
7276:
7274:
7271:
7269:
7268:Crag and tail
7266:
7264:
7261:
7259:
7256:
7254:
7251:
7250:
7248:
7244:
7241:
7239:
7235:
7229:
7226:
7224:
7221:
7219:
7216:
7214:
7211:
7210:
7208:
7204:
7198:
7195:
7193:
7190:
7189:
7187:
7183:
7177:
7174:
7172:
7169:
7167:
7164:
7162:
7159:
7157:
7154:
7152:
7151:Overdeepening
7149:
7147:
7144:
7142:
7139:
7137:
7134:
7132:
7129:
7127:
7126:Basal sliding
7124:
7122:
7119:
7117:
7114:
7113:
7111:
7107:
7101:
7098:
7096:
7093:
7091:
7088:
7086:
7083:
7081:
7078:
7076:
7073:
7071:
7068:
7066:
7063:
7061:
7058:
7056:
7053:
7051:
7048:
7046:
7043:
7041:
7038:
7036:
7033:
7031:
7028:
7026:
7023:
7021:
7018:
7016:
7013:
7011:
7008:
7006:
7005:Ablation zone
7003:
7002:
7000:
6996:
6990:
6987:
6985:
6982:
6980:
6977:
6975:
6972:
6970:
6967:
6965:
6962:
6960:
6957:
6955:
6952:
6950:
6947:
6945:
6942:
6940:
6937:
6935:
6932:
6931:
6929:
6925:
6921:
6914:
6909:
6907:
6902:
6900:
6895:
6894:
6891:
6879:
6876:
6874:
6871:
6869:
6866:
6864:
6861:
6859:
6856:
6854:
6851:
6849:
6846:
6844:
6841:
6840:
6838:
6834:
6828:
6825:
6824:
6822:
6818:
6812:
6809:
6808:
6806:
6802:
6792:
6789:
6787:
6784:
6782:
6779:
6777:
6774:
6772:
6769:
6768:
6766:
6764:
6760:
6754:
6751:
6749:
6746:
6744:
6741:
6737:
6734:
6732:
6729:
6727:
6724:
6722:
6719:
6718:
6717:
6714:
6712:
6709:
6707:
6704:
6702:
6699:
6697:
6694:
6692:
6689:
6687:
6684:
6682:
6679:
6678:
6676:
6674:
6670:
6667:
6665:
6662:Chronological
6659:
6649:
6646:
6644:
6641:
6639:
6636:
6634:
6631:
6629:
6628:Geochronology
6626:
6624:
6621:
6620:
6618:
6614:
6608:
6605:
6603:
6600:
6599:
6597:
6593:
6587:
6584:
6582:
6579:
6577:
6574:
6573:
6571:
6567:
6564:
6562:
6561:Geologic time
6558:
6552:
6549:
6547:
6546:Metonic cycle
6544:
6542:
6541:Galactic year
6539:
6537:
6534:
6532:
6529:
6528:
6526:
6524:
6520:
6510:
6507:
6505:
6502:
6498:
6495:
6493:
6490:
6489:
6488:
6485:
6483:
6482:ISO week date
6480:
6478:
6475:
6473:
6470:
6468:
6465:
6464:
6462:
6458:
6452:
6449:
6446:
6442:
6439:
6437:
6434:
6431:
6427:
6423:
6420:
6419:
6417:
6413:
6407:
6404:
6402:
6399:
6397:
6394:
6392:
6389:
6387:
6384:
6383:
6381:
6377:
6371:
6368:
6366:
6363:
6361:
6358:
6356:
6353:
6352:
6350:
6346:
6343:
6341:
6337:
6327:
6324:
6322:
6319:
6317:
6314:
6312:
6309:
6308:
6306:
6304:
6300:
6294:
6291:
6289:
6286:
6284:
6281:
6279:
6276:
6274:
6271:
6270:
6268:
6266:
6262:
6254:
6251:
6249:
6246:
6244:
6241:
6239:
6236:
6235:
6234:
6231:
6228:
6224:
6221:
6219:
6216:
6214:
6211:
6209:
6206:
6204:
6201:
6199:
6196:
6194:
6191:
6189:
6188:Byzantine era
6186:
6184:
6181:
6179:
6176:
6174:
6171:
6169:
6165:
6162:
6160:
6159:
6155:
6153:
6150:
6149:
6147:
6145:
6144:Calendar eras
6141:
6138:
6133:
6130:
6128:
6125:
6123:
6120:
6119:
6116:
6110:
6107:
6105:
6102:
6098:
6095:
6094:
6093:
6090:
6088:
6085:
6083:
6080:
6078:
6075:
6074:
6072:
6068:
6064:
6057:
6052:
6050:
6045:
6043:
6038:
6037:
6034:
6028:
6025:
6023:
6020:
6018:
6015:
6013:
6010:
6008:
6005:
6003:
6000:
5998:
5995:
5994:
5975:
5968:
5963:
5959:
5953:
5949:
5944:
5939:
5934:
5930:
5926:
5923:(68): 15–26.
5922:
5918:
5914:
5908:
5904:
5900:
5896:
5891:
5887:
5881:
5877:
5872:
5868:
5864:
5860:
5856:
5852:
5848:
5844:
5840:
5836:
5831:
5824:
5820:
5813:
5808:
5803:
5798:
5794:
5790:
5786:
5782:
5775:
5762:
5757:
5752:
5748:
5744:
5740:
5736:
5732:
5727:
5720:
5713:
5708:
5703:
5698:
5694:
5690:
5686:
5682:
5678:
5673:
5668:
5663:
5659:
5655:
5651:
5647:
5643:
5638:
5634:
5628:
5624:
5619:
5618:
5605:
5601:
5597:
5590:
5588:
5571:
5567:
5561:
5554:
5549:
5542:
5537:
5530:
5525:
5518:
5513:
5506:
5501:
5494:
5489:
5481:
5477:
5471:
5456:
5450:
5434:
5430:
5423:
5416:
5411:
5395:
5391:
5385:
5369:
5362:
5353:
5348:
5344:
5340:
5336:
5332:
5328:
5321:
5314:
5309:
5307:
5305:
5303:
5295:
5290:
5288:
5286:
5278:
5273:
5266:
5261:
5254:
5249:
5242:
5237:
5230:
5225:
5223:
5215:
5210:
5203:
5198:
5191:
5186:
5179:
5174:
5167:
5162:
5155:
5150:
5143:
5138:
5129:
5124:
5120:
5116:
5112:
5108:
5104:
5097:
5088:
5083:
5079:
5075:
5071:
5064:
5045:
5038:
5031:
5024:
5019:
5011:
5007:
5006:"Future Work"
5001:
4992:
4984:
4980:
4976:
4972:
4968:
4964:
4960:
4956:
4952:
4948:
4941:
4934:
4925:
4920:
4916:
4912:
4908:
4901:
4892:
4887:
4883:
4879:
4875:
4871:
4867:
4860:
4853:
4848:
4841:
4836:
4829:
4824:
4822:
4814:
4809:
4802:
4797:
4790:
4785:
4783:
4774:
4770:
4766:
4762:
4758:
4754:
4750:
4746:
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4015:
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3999:
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3955:9780444536426
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3649:
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3620:
3613:
3606:
3601:
3599:
3597:
3595:
3584:
3579:
3575:
3571:
3567:
3563:
3562:Eos Trans AGU
3559:
3552:
3545:
3540:
3538:
3536:
3534:
3518:on 4 May 2017
3517:
3513:
3506:
3504:
3488:
3484:
3477:
3470:
3465:
3449:
3445:
3441:
3434:
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3406:
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3398:
3391:
3376:
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3356:
3347:
3342:
3338:
3334:
3330:
3323:
3315:
3309:
3305:
3298:
3289:
3284:
3280:
3276:
3272:
3265:
3258:
3253:
3246:
3241:
3234:
3229:
3222:
3217:
3210:
3205:
3203:
3195:
3190:
3181:
3176:
3172:
3168:
3164:
3157:
3141:
3137:
3131:
3124:
3119:
3117:
3109:
3104:
3102:
3094:
3089:
3087:
3085:
3083:
3075:
3070:
3068:
3060:
3055:
3047:
3041:
3037:
3030:
3011:
3004:
2997:
2989:
2983:
2979:
2975:
2974:
2966:
2959:
2954:
2946:
2940:
2936:
2929:
2922:
2917:
2915:
2907:
2902:
2900:
2898:
2890:
2885:
2883:
2867:
2860:
2856:
2847:
2844:
2842:
2839:
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2826:
2822:
2814:
2811:
2808:
2805:
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2799:
2796:
2793:
2789:
2788:
2787:
2785:
2776:
2774:
2770:
2766:
2762:
2758:
2748:
2746:
2742:
2738:
2734:
2730:
2726:
2716:
2713:
2708:
2706:
2702:
2698:
2694:
2690:
2686:
2682:
2678:
2674:
2669:
2667:
2663:
2655:
2651:
2648:
2644:
2643:Novaya Zemlya
2640:
2636:
2632:
2620:
2611:
2609:
2608:Devon Ice Cap
2605:
2601:
2597:
2593:
2588:
2585:
2581:
2577:
2573:
2568:
2564:
2559:
2557:
2553:
2549:
2545:
2541:
2537:
2532:
2527:
2524:
2523:Pavel Talalay
2520:
2516:
2512:
2508:
2504:
2503:Louis Agassiz
2495:
2485:
2475:
2473:
2463:
2461:
2457:
2446:
2443:
2430:
2417:
2404:
2392:
2377:
2362:
2358:
2343:
2328:
2321:
2317:
2311:Radionuclides
2203:
2187:
2137:
2135:
2131:
2052:
2051:
2048:
1998:
1995:
1992:
1991:
1921:
1918:
1915:
1914:
1910:
1907:
1904:
1903:
1897:
1873:
1871:
1867:
1863:
1858:
1852:
1809:
1805:
1800:
1777:
1764:
1760:
1756:
1752:
1747:
1745:
1740:
1735:
1730:
1726:
1722:
1712:
1701:
1699:
1695:
1691:
1687:
1683:
1679:
1675:
1671:
1668:ratio and of
1645:
1644:fractionation
1640:
1636:
1501:
1497:
1493:
1489:
1485:
1468:
1454:
1438:
1429:
1422:
1413:
1404:
1390:
1364:
1360:
1356:
1352:
1347:
1345:
1340:
1327:
1319:
1310:
1306:
1301:
1298:
1295:
1288:
1279:
1259:
1230:
1225:
1161:
1156:
1143:
1138:
1135:
1128:
1121:
1113:
1110:
1100:
1097:
1060:
1057:
1046:
1043:
990:
987:
976:
973:
949:
940:
936:
926:
924:
831:
818:
805:
787:
783:
779:
775:
771:
762:
753:
751:
750:Richard Alley
746:
744:
740:
736:
731:
729:
725:
724:Uranium decay
721:
717:
713:
697:
693:
687:
685:
681:
666:
641:
637:
609:
605:
601:
599:
594:
589:
587:
583:
579:
575:
574:radionuclides
571:
559:Ice core data
556:
552:
550:
545:
534:
527:
515:
501:
499:
494:
492:
486:
483:
477:
471:
466:
457:
455:
451:
448:owned by the
447:
443:
439:
435:
431:
427:
423:
412:
408:
406:
402:
397:
393:
392:to the core.
391:
390:thermal shock
387:
381:
378:
368:
364:
362:
357:
352:
347:
345:
341:
337:
333:
329:
325:
321:
320:fluorocarbons
317:
313:
308:
304:
299:
297:
293:
288:
285:
281:
277:
273:
269:
265:
256:
251:
241:
238:
234:
228:
226:
222:
218:
214:
210:
206:
201:
199:
194:
192:
188:
184:
180:
176:
167:
163:
158:
153:
143:
141:
137:
133:
129:
125:
121:
117:
113:
109:
104:
102:
98:
94:
90:
86:
81:
79:
78:climate model
75:
71:
67:
63:
59:
54:
52:
48:
44:
40:
36:
32:
23:
19:
7369:Depositional
7359:Zungenbecken
7357:
7288:Glacial lake
7283:Glacial horn
7197:Mass balance
7191:
7185:Measurements
7121:Accumulation
7045:Glacier head
7040:Glacier cave
6984:Rock glacier
6791:Stratigraphy
6736:Uranium–lead
6706:Lichenometry
6695:
6504:Winter count
6487:Mesoamerican
6415:Astronomical
6233:Mesoamerican
6218:Sothic cycle
6193:Seleucid era
6178:Bosporan era
6166: /
6156:
6104:Paleontology
5980:14 September
5978:. Retrieved
5947:
5920:
5916:
5894:
5875:
5842:
5838:
5823:the original
5819:CRREL Report
5818:
5784:
5780:
5738:
5734:
5719:the original
5684:
5680:
5649:
5645:
5622:
5599:
5574:. Retrieved
5570:the original
5560:
5548:
5536:
5524:
5512:
5500:
5488:
5479:
5470:
5458:. Retrieved
5449:
5437:. Retrieved
5433:the original
5422:
5417:, pp. 27–28.
5415:Langway 2008
5410:
5398:. Retrieved
5393:
5384:
5372:. Retrieved
5361:
5334:
5330:
5320:
5272:
5260:
5255:, pp. 50–58.
5248:
5236:
5214:Langway 2008
5209:
5204:, pp. 17–20.
5202:Langway 2008
5197:
5192:, pp. 14–15.
5190:Langway 2008
5185:
5178:Langway 2008
5173:
5166:Langway 2008
5161:
5154:Langway 2008
5149:
5142:Talalay 2016
5137:
5110:
5106:
5096:
5077:
5073:
5063:
5053:14 September
5051:. Retrieved
5030:
5018:
5010:the original
5000:
4991:
4950:
4946:
4933:
4914:
4910:
4900:
4873:
4869:
4859:
4847:
4835:
4808:
4796:
4740:
4736:
4725:
4705:, pp. 51–55.
4698:
4681:
4677:
4667:
4640:
4636:
4626:
4607:
4583:
4571:. Retrieved
4564:the original
4551:
4547:
4534:
4507:. Retrieved
4497:
4452:
4448:
4438:
4426:
4399:. Retrieved
4388:
4376:. Retrieved
4372:the original
4362:
4350:
4330:, pp. 65–70.
4323:
4292:. Retrieved
4281:
4269:
4252:
4239:
4227:
4202:
4198:
4141:
4136:, pp. 50–51.
4129:
4117:
4112:, pp. 44–48.
4105:
4097:the original
4086:
4051:
4047:
4033:
4021:. Retrieved
4014:the original
4005:
3998:
3986:
3977:
3964:
3945:
3939:
3912:
3900:
3888:
3876:. Retrieved
3871:
3862:
3835:
3831:
3821:
3794:
3790:
3784:
3776:
3749:
3737:
3700:
3696:
3685:
3674:the original
3655:
3648:
3641:Talalay 2016
3636:
3626:
3622:
3612:
3607:, pp. 20–21.
3565:
3561:
3551:
3546:, pp. 16–19.
3520:. Retrieved
3516:the original
3490:. Retrieved
3486:
3476:
3464:
3452:. Retrieved
3448:the original
3443:
3433:
3428:, pp. 17–19.
3421:
3409:. Retrieved
3405:the original
3400:
3390:
3378:. Retrieved
3374:
3364:
3355:
3336:
3332:
3322:
3303:
3297:
3278:
3274:
3264:
3257:Talalay 2016
3252:
3245:Talalay 2016
3240:
3233:Talalay 2016
3228:
3221:Talalay 2016
3216:
3209:Talalay 2016
3194:Talalay 2016
3189:
3170:
3166:
3156:
3144:. Retrieved
3140:the original
3130:
3123:Talalay 2016
3108:Talalay 2016
3093:Talalay 2016
3076:, pp. 34–35.
3074:Talalay 2016
3061:, pp. 43–46.
3054:
3035:
3029:
3017:. Retrieved
3010:the original
2996:
2972:
2965:
2960:, pp. 35–36.
2953:
2934:
2928:
2921:Talalay 2016
2908:, pp. 48–50.
2891:, pp. 71–73.
2869:. Retrieved
2859:
2846:Ice drilling
2818:
2782:
2779:Future plans
2754:
2722:
2709:
2670:
2660:
2629:
2589:
2572:Byrd Station
2560:
2542:(NBSAE), in
2528:
2500:
2469:
2452:
2325:
2130:hydrocarbons
1874:
1862:carbon black
1806:over time.
1748:
1718:
1702:
1698:stratosphere
1637:
1492:low-latitude
1469:
1434:
1389:carbon cycle
1363:interglacial
1351:Camp Century
1348:
1341:
1280:
1226:
1157:
927:
793:
784:
780:
776:
772:
768:
747:
732:
688:
680:particulates
606:
602:
590:
567:
553:
541:
495:
487:
478:
475:
418:
409:
398:
394:
382:
377:leaf-springs
373:
361:drill string
348:
334:, including
300:
289:
276:brace handle
261:
250:Ice drilling
229:
213:beryllium-10
205:forest fires
202:
195:
171:
162:Taku Glacier
112:Byrd Station
105:
82:
55:
30:
28:
18:
7474:Outwash fan
7469:Kettle hole
7353:Valley step
7333:Trough lake
7313:Ribbon lake
7273:Finger lake
7015:Bergschrund
6731:Radiocarbon
6406:Dual dating
6265:Regnal year
6243:Short Count
6183:Bostran era
6164:Anno Domini
6097:Big History
6077:Archaeology
5543:, p. 26-29.
5313:Jouzel 2013
5294:Jouzel 2013
5267:, pp. 3–26.
5229:Jouzel 2013
5180:, pp. 9–11.
5144:, pp. 9–11.
5080:(63): 183.
4917:: 307–312.
4527:Jouzel 2013
4431:Jouzel 2013
4419:Jouzel 2013
4343:Jouzel 2013
4232:Jouzel 2013
4175:Jouzel 2013
4054:(1): 3–17.
4023:5 September
3791:Radiocarbon
3754:Jouzel 2013
3742:Jouzel 2013
3728:2158/969431
3568:(49): 549.
2712:Allan Hills
2681:Taylor Dome
2602:drilled by
2598:; cores at
2550:(JIRP), in
2489:Early years
2134:halocarbons
1415:Graph of CO
1403:over time.
735:Pleistocene
544:brittle ice
504:Brittle ice
482:WAIS Divide
468:Sawing the
217:cosmic rays
215:created by
179:Summit Camp
97:Radioactive
35:core sample
7547:Glaciology
7531:Categories
7501:Glaciology
7484:Urstromtal
7464:Kame delta
7416:Till plain
7213:Jökulhlaup
7171:Starvation
7050:Ice divide
6964:Ice stream
6326:Vietnamese
6238:Long Count
6173:Anno Mundi
6168:Common Era
6070:Key topics
6063:Chronology
5337:(1): 3–4.
5315:, p. 2529.
5296:, p. 2528.
5243:, pp. 3–5.
5231:, p. 2527.
5156:, pp. 5–6.
5023:Alley 2000
4703:Alley 2000
4529:, p. 2534.
4433:, p. 2531.
4357:, p. 1097.
4355:Alley 2010
4345:, p. 2532.
4328:Alley 2000
4234:, p. 2533.
4177:, p. 2530.
4146:Alley 2000
4134:Alley 2000
4122:Alley 2000
4110:Alley 2000
3771:, p. 1098.
3769:Alley 2010
3756:, p. 2535.
3629:(49): 302.
3471:, pp. 8–9.
3397:"Partners"
3059:Alley 2000
2958:Alley 2000
2906:Alley 2000
2889:Alley 2000
2852:References
2705:Talos Dome
2685:Siple Dome
2567:glaciology
2482:See also:
1922:Sea salt:
1804:combustion
1729:electrodes
1694:ozone loss
1496:insolation
386:antifreeze
359:which the
305:to reduce
248:See also:
237:hoar frost
150:See also:
64:, and the
49:with hand
7542:Water ice
7246:Erosional
7238:Landforms
7109:Processes
7090:Randkluft
7085:Penitente
7030:Dirt cone
6959:Ice shelf
6954:Ice sheet
6949:Ice field
6863:Year zero
6843:Chronicle
6786:Seriation
6721:Lead–lead
6595:Standards
6576:Deep time
6536:Ephemeris
6422:Lunisolar
6386:Gregorian
6379:Gregorian
6340:Calendars
6303:Era names
6273:Anka year
6152:Human Era
6082:Astronomy
5903:0149-1776
5460:21 August
5400:30 August
4983:206558530
4854:, p. 228.
4830:, p. 225.
4815:, p. 222.
4791:, p. 221.
4590:, p. 191.
3993:, p. 315.
3934:, p. 192.
3895:, p. 325.
3211:, p. 101.
2923:, p. 263.
2829:ice cores
2757:Himalayas
2733:NorthGRIP
2707:in 2007.
2645:, and at
2578:, on the
1639:Diffusion
1307:δ
1302:×
1289:δ
1229:Deuterium
1111:×
1098:−
937:δ
636:carbonate
491:polythene
303:viscosity
233:sublimate
209:volcanoes
191:clathrate
89:Greenland
74:heat flow
72:. Since
39:ice sheet
7506:Category
7444:Diluvium
7439:Alpentor
7348:U-valley
7192:Ice core
7161:Plucking
7116:Ablation
7100:Terminus
7025:Crevasse
7020:Blue ice
6920:Glaciers
6858:Timeline
6696:Ice core
6569:Concepts
6316:Japanese
6248:Tzolk'in
6213:Egyptian
5974:Archived
5867:55357216
5604:Archived
5555:, p. 30.
5531:, p. 39.
5519:, p. 36.
5507:, p. 42.
5495:, p. 41.
5439:17 March
5279:, p. 11.
5216:, p. 23.
5044:Archived
5025:, p. 73.
4975:27244483
4765:26153860
4678:Tellus B
4606:(2010).
4489:26976561
4276:, p. 25.
4148:, p. 56.
4124:, p. 49.
4078:40380068
3872:Phys.org
3223:, p. 79.
3125:, p. 77.
3095:, p. 59.
2973:Glaciers
2835:See also
2759:and the
2741:EastGRIP
2600:Law Dome
2329:produce
1870:ammonium
1488:monsoons
1484:wetlands
1470:Because
925:(SMOW):
739:Holocene
737:and the
642:). The
444:, using
422:EastGRIP
356:wireline
316:kerosene
312:toxicity
307:tripping
292:cuttings
272:T handle
198:icebergs
130:and the
58:isotopes
31:ice core
7386:Moraine
7376:Drumlin
7303:Nunatak
7166:Retreat
7131:Calving
7075:Moraine
7060:Icefall
6998:Anatomy
6969:Ledoyom
6944:Ice cap
6868:Floruit
6616:Methods
6477:Iranian
6445:Islamic
6311:Chinese
6122:Periods
6092:History
6087:Geology
5925:Bibcode
5847:Bibcode
5789:Bibcode
5743:Bibcode
5689:Bibcode
5654:Bibcode
5614:Sources
5576:17 June
5394:Science
5339:Bibcode
5168:, p. 7.
5115:Bibcode
4955:Bibcode
4878:Bibcode
4773:4462058
4745:Bibcode
4645:Bibcode
4480:4822573
4457:Bibcode
4207:Bibcode
4056:Bibcode
3840:Bibcode
3799:Bibcode
3785:in-situ
3705:Bibcode
3570:Bibcode
3492:17 June
3454:17 June
3411:17 June
3380:17 June
3110:, p. 7.
3019:17 June
2871:5 April
2791:cycles.
2765:El Niño
2509:in the
2478:History
2376:Tritium
1916:Oceans
1905:Source
1866:calcium
1810:(MSA) (
1759:cadmium
1739:Tambora
1696:in the
1674:krypton
1494:summer
765:layers.
712:methane
684:organic
593:diffuse
578:species
438:Denmark
328:ethanol
268:helical
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7479:Sandur
7323:Suncup
7308:P-form
7258:Cirque
7141:Motion
7080:Moulin
6939:Cirque
6934:Aufeis
6664:dating
6460:Others
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6321:Korean
6132:Epochs
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5901:
5882:
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5374:28 May
4981:
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4573:2 June
4509:3 June
4487:
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4378:25 May
4294:20 May
4076:
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3952:
3878:29 May
3666:
3522:21 May
3310:
3146:3 June
3042:
2984:
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2673:Dome F
2637:, the
2631:Soviet
2592:Dome C
2554:; and
2552:Alaska
2460:Pollen
1761:, and
1755:copper
1682:helium
1344:Jouzel
1276:δ
1269:δ
1262:δ
1256:δ
1219:δ
1211:δ
1204:δ
1186:δ
1118:
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598:Vostok
564:Dating
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342:oils,
332:esters
284:tripod
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244:Coring
225:pollen
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7253:Arête
7176:Surge
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6927:Types
6497:Aztec
6441:Lunar
6436:Solar
6430:Hindu
6293:Limmu
6253:Haab'
6208:Hijri
5970:(PDF)
5863:S2CID
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5815:(PDF)
5777:(PDF)
5722:(PDF)
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