TY - JOUR
T1 - The past, present, and future viscous heat dissipation available for Greenland subglacial conduit formation
AU - Mankoff, Kenneth D.
AU - Tulaczyk, Slawek M.
N1 - Funding Information:
We thank D. van As for initial discussions on this topic, M. Morlighem and X. Fettweis for providing accessible and documented data, R. Bell for sharing data, and D. Pollard, anonymous referees, and The Cryosphere Discussion reviewers for comments. Kenneth D. Mankoff was funded by NASA Headquarters under the NASA Earth and Space Science Fellowship Program (Grant NNX10AN83H) and the Postdoctoral Scholar Program at the Woods Hole Oceanographic Institution, with funding provided by the Ocean and Climate Change Institute. Slawek M. Tulaczyk was funded by NASA grant NNX11AH61G.
Publisher Copyright:
© Author(s) 2017.
PY - 2017/1/30
Y1 - 2017/1/30
N2 - Basal hydrology of the Greenland Ice Sheet (GIS) influences its dynamics and mass balance through basal lubrication and ice-bed decoupling or efficient water removal and ice-bed coupling. Variations in subglacial water pressure through the seasonal evolution of the subglacial hydrological system help control ice velocity. Near the ice sheet margin, large basal conduits are melted by the viscous heat dissipation (VHD) from surface runoff routed to the bed. These conduits may lead to efficient drainage systems that lower subglacial water pressure, increase basal effective stress, and reduce ice velocity. In this study we quantify the energy available for VHD historically at present and under future climate scenarios. At present, 345km3 of annual runoff delivers 66GW to the base of the ice sheet per year. These values are already ~50% more than the historical 1960-1999 value of 46GW. By 2100 under IPCC AR5 RCP8.5 (RCP4.5) scenarios, 1278 (524)km3 of runoff may deliver 310 (110)GW to the ice sheet base. Hence, the ice sheet may experience a 5-to-7-fold increase in VHD in the near future which will enhance opening of subglacial conduits near the margin and will warm basal ice in the interior. The other significant basal heat source is geothermal heat flux (GHF), which has an estimated value of 36 GW within the present-day VHD area. With increasing surface meltwater penetration to the bed the basal heat budget in the active basal hydrology zone of the GIS will be increasingly dominated by VHD and relatively less sensitive to GHF, which may result in spatial changes in the ice flow field and in its seasonal variability.
AB - Basal hydrology of the Greenland Ice Sheet (GIS) influences its dynamics and mass balance through basal lubrication and ice-bed decoupling or efficient water removal and ice-bed coupling. Variations in subglacial water pressure through the seasonal evolution of the subglacial hydrological system help control ice velocity. Near the ice sheet margin, large basal conduits are melted by the viscous heat dissipation (VHD) from surface runoff routed to the bed. These conduits may lead to efficient drainage systems that lower subglacial water pressure, increase basal effective stress, and reduce ice velocity. In this study we quantify the energy available for VHD historically at present and under future climate scenarios. At present, 345km3 of annual runoff delivers 66GW to the base of the ice sheet per year. These values are already ~50% more than the historical 1960-1999 value of 46GW. By 2100 under IPCC AR5 RCP8.5 (RCP4.5) scenarios, 1278 (524)km3 of runoff may deliver 310 (110)GW to the ice sheet base. Hence, the ice sheet may experience a 5-to-7-fold increase in VHD in the near future which will enhance opening of subglacial conduits near the margin and will warm basal ice in the interior. The other significant basal heat source is geothermal heat flux (GHF), which has an estimated value of 36 GW within the present-day VHD area. With increasing surface meltwater penetration to the bed the basal heat budget in the active basal hydrology zone of the GIS will be increasingly dominated by VHD and relatively less sensitive to GHF, which may result in spatial changes in the ice flow field and in its seasonal variability.
UR - http://www.scopus.com/inward/record.url?scp=85011418956&partnerID=8YFLogxK
U2 - 10.5194/tc-11-303-2017
DO - 10.5194/tc-11-303-2017
M3 - Article
AN - SCOPUS:85011418956
SN - 1994-0416
VL - 11
SP - 303
EP - 317
JO - Cryosphere
JF - Cryosphere
IS - 1
ER -
