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. Author manuscript; available in PMC: 2017 Aug 10.
Published in final edited form as: J Geophys Res Earth Surf. 2016 Jul 23;121(7):1328–1350. doi: 10.1002/2015JF003803

Table 1.

Boreholes and Known Subglacial Lakes Used to Evaluate Inferences of the Thermal State of the Bed of the GrIS.

Borehole /
subglacial lake		 Latitude
(°N)		 Longitude
(°W)		 Ice
thickness
(m)		 Basal
temperature
obs. /
correcteda
(°C)		 Reference
Boreholes
Interior
Camp Century 77.18 61.13 1387 −13.0 / −11.8 Weertman [1968]
DYE-3 65.18 43.82 2037 −13.2 / −11.4 Gundestrup and Hansen [1984]
GISP2 72.60 38.50 3053 −9.2 / −6.6 Cuffey et al. [1995]
GRIP 72.58 37.64 3029 −8.6 / −6.0 Bender et al. [2010]
NEEM 77.45 51.06 2538b −3.5 / −1.3 MacGregor et al. [2015b]c
NorthGRIP 75.10 42.32 3085 ~ −2.3 / 0 Dahl-Jensen et al. [2003]d
Southwestern
margin
Swiss Camp 69.57 49.28 N/A T Thomsen et al. [1991]
Jakobshavn
Isbræ		 ~69.19 ~48.77 1540–
1630		 −1.1 / 0 Iken et al. [1993]
Jakobshavn
Isbræ		 69.24 48.69 830 −0.6 / 0 Lüthi et al. [2002]
Paakitsoq 69.45 49.88 614–624 −0.5 / 0 Lüthi et al. [2015]
Isunnguata
Sermia		 ~67.19 ~49.52 92–821 −0.7 – −0.1 / 0 Harrington et al. [2015]
Peripheral ice
caps
Renland 71.30 26.72 324 F Hansson [1994]
Hans Tausen 82.50 37.52 345 F Madsen and Thorsteinsson [2001]
Flade Isblink 81.29 15.70 540 F Lemark [2010]
Subglacial lakes
Northwestern
margin		 ~77.92 ~68.89 757–809 T Palmer et al. [2013]
Southwestern
margin		 67.61 48.69 1200 T Howat et al. [2015]
Flade Isblink 81.16 16.58 540 T Willis et al. [2015]
a

“corrected” means corrected for pressure-melting using local ice thickness. Where basal temperatures were not measured directly but confidently inferred, we give the basal thermal state as either frozen (F) or thawed (T).

b

Note that ice thickness at NEEM was reported incorrectly by MacGregor et al. [2015a,b] as 2561 m.

c

The deepest measured temperature was −3.56°C at 2537.36 m. An additional 0.63 m of silty ice was drilled following this measurement, resulting in an extrapolated basal temperature of −3.54°C.

d

Dahl-Jensen et al. [2003] estimated a basal temperature of −2.4°C based on the deepest measured temperature available at the time (−7.8°C at 2880 m). Following further drilling, the temperature measured at 2992.6 m was −5.17°C. Drilling eventually reached the bed but the basal temperature was not measured there. Here we use the newer, deeper temperature measurement and the observed vertical temperature gradient (31 mK m−1) to estimate the basal temperature.