Editing Ice core (section)

=== Greenland deep cores ===
In 1970, scientific discussions began which resulted in the [[Greenland Ice Sheet Project]] (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&nbsp;m in 1971), Milcent (398&nbsp;m in 1973) and Crete (405&nbsp;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&nbsp;m, in 1981.  Two holes, 30&nbsp;km apart, were eventually drilled at the north-central location in the early 1990s by two groups: [[Greenland Ice Core Project|GRIP]], a European consortium, and GISP-2, a group of US universities.  GRIP reached bedrock at 3029&nbsp;m in 1992, and GISP-2 reached bedrock at 3053&nbsp;m the following year.<ref>{{harvnb|Langway|2008}}, pp. 27–28.</ref> 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&nbsp;km north of GRIP, and a new project, [[North Greenland Ice Core Project|NorthGRIP]], was launched as an international consortium led by Denmark.  Drilling began in 1996; the first hole had to be abandoned at 1400&nbsp;m in 1997, and a new hole was begun in 1999, reaching 3085&nbsp;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 ([[NEEM Camp|NEEM]]) project retrieved a 2537&nbsp;m core in 2010 from a site further north, extending the climatic record to 128,500 years ago;<ref name="Jouzel-2013-2">{{harvnb|Jouzel|2013}}, p. 2528.</ref> NEEM was followed by [[East Greenland Ice-Core Project|EastGRIP]], which began in 2015 in east Greenland and was planned to be completed in 2020.<ref>{{Cite web|url=http://eastgrip.org/documentation/|title=Documentation|last=Madsen|first=Martin Vindbæk|date=15 March 2016|publisher=East Greenland Ice Core Project|language=en|access-date=17 March 2017|archive-url=https://web.archive.org/web/20170318090450/http://eastgrip.org/documentation/|archive-date=18 March 2017|url-status=dead}}</ref>
In March 2020, the 2020 EGRIP field campaign was cancelled due to the ongoing [[COVID-19 pandemic]]. 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.<ref>{{cite web|url=https://eastgrip.org/FieldDiaries/2022diaries/2022-05-07.html|title=Finally, put in at EGRIP|access-date=2023-08-21}}</ref><ref>{{Cite web|url=https://protronix.co.uk/surviving-harsh-operating-conditions-how-protronix-ems-is-powering-cutting-edge-research-in-east-greenland/|title=Surviving Harsh Operating Conditions: How Protronix EMS is Powering Cutting-Edge Research in East Greenland &#124; Protronix EMS|website=protronix.co.uk/}}</ref>