Glaciers in the Earth’s Hydrological Cycle: Assessments of Glacier Mass and Runoff Changes on Global and Regional Scales - The Earth's Hydrological Cycle - page 330

Table 2 Overview of studies projecting global glacier mass changes for the twenty-first century

Period Projected SLE (mm) Climate Scenario Reference

All glaciers Excl. A ? G

2001-2100 46, 51 SRES A1B, 2 GCMs Raper and Braithwaite ( 2006 )

2001-2100 124 ± 37 99 ± 33 SRES A1B, 10 GCMs Radi´ and Hock ( 2011 )

2006-2100 148 ± 35 RCP2.6, 13 GCMs Marzeion et al. ( 2012 )

2006-2100 166 ± 42 RCP4.5, 15 GCMs Marzeion et al. ( 2012 )

2006-2100 175 ± 40 RCP6.0, 11 GCMs Marzeion et al. ( 2012 )

2006-2100 217 ± 47 RCP8.5, 15 GCMs Marzeion et al. ( 2012 )

2000-2099 159 ± 52 116 SRES A1B, 12 GCMs Slangen et al. ( 2012 )

2001-2100 150 ± 37 114 ± 30 SRES A1B, 10 GCMs Radi´ et al. ( 2013 )

2006-2100 155 ± 41 122 ± 36 RCP4.5, 14 GCMs Radi´ et al. ( 2013 )

2006-2100 216 ± 44 167 ± 38 RCP8.5, 14 GCMs Radi´ et al. ( 2013 )

73 ± 14 a 2006-2099 RCP8.5, 10 GCMs Hirabayashi et al. ( 2013 )

2012-2099 102 ± 28 64 SRES A1B, 8 GCMs Giesen and Oerlemans ( 2013 )
a Here calculated by subtracting the reported projections for the period 1948-2005 (25.9±1.4 mm SLE)
from the period 1948-2099 (99.0±14.9 mm SLE) in Hirabayashi et al. ( 2013 ).

d b

dT DT þ d b

DM
Dt ¼ S dP DP

d b
dT

d b

where

dP are mass-balance sensitivities to temperature and precipitation change,
respectively, and S is glacier surface area (e.g., Hock et al. 2009 ). The specific mass-
balance rate, b, is typically in m water equivalent (w.e.) year -1 .
Several studies have found that glaciers in wetter or maritime climates tend to be more
sensitive to temperature and precipitation changes than subpolar glaciers or glaciers in
continental climates (e.g., Oerlemans and Fortuin 1992 ; Braithwaite and Zhang 1999 ;de
Woul and Hock 2005 ). Quantifying the relations between mass-balance sensitivities and
climate variables enables extrapolation of the sensitivities to glaciers without mass-balance
observations. For the purpose of projecting global glacier mass changes, this approach was
first applied in Gregory and Oerlemans ( 1998 ), further developed in Van de Wal and Wild
( 2001 ), and recently used for regional projections of twenty-first century sea-level change
based on IPCC AR4 SRES scenarios (Slangen et al. 2012 ). In Slangen et al. ( 2012 ), the
mass balance sensitivity ( d b

and

dT ) is differentiated between summer and non-summer months,
accounting for seasonality in glacier mass balance. Future scenarios of temperature and
precipitation changes are taken from an ensemble of 12 global climate models (GCMs),
and the results for the A1B emission scenario show a glacier contribution to the twenty-
first century sea-level rise of 130-250 mm.
Hock et al. ( 2009 ) used a mass-balance sensitivity approach to reconstruct the average
global glacier mass balance spatially resolved on a 0.5 global glacier grid (Cogley 2003 )
for the period 1961-2004 using gridded reanalysis temperature and precipitation trends. At
the time of publication, this study was the only alternative approach to spatial interpolation
of local mass-balance observations (Sect. 2.1 ). Their global estimate of 0.79 ± 0.34 mm
SLE year -1 was larger than the consensus estimate of 0.50 ± 0.22 mm SLE year -1 by
Kaser et al. ( 2006 ) for the same period, mainly due to large modeled mass loss of glaciers