GEOPHYSICAL RESEARCH LETTERS, VOL. ???, XXXX, DOI:10.1029/,

Contribution of Icelandic ice caps to sea level rise: trends and variability since the Little Ice Age Helgi Bjrnsson1, Finnur Plsson1, Sverrir Gudmundsson1, Eyjlfur Magnsson1, Gudfinna Adalgeirsdttir1, Tmas Jhannesson2, Etienne Berthier3, Oddur Sigurdsson2and Thorsteinn Thorsteinsson2 Table 1. The in situ mass balance of Iceland’s three largest ice caps and estimated total mass loss of all ice masses in Iceland (also presented in Figures 2d and 3). Accuracy: ±0.15 mwe a−1 and ±1.5 Gt a−1 . Sources for Vatnajökull and Langjökull: Institute of Earth Sciences, University of Iceland, Björnsson, H., F. Pálsson., S. Gudmundsson, E. Magnússon and H. H. Haraldsson. Sources for Hofsjökull: Icelandic Meteorolgical Office, Th. Thorsteinsson, O. Sigurðsson and T. Jóhannesson. Ice caps Glaciol. bw year mwe a−1 1987−88 1988−89 1989−90 1990−91 1991−92 2.1 1992−93 1.8 1993−94 1.7 1994−95 1.6 1995−96 1.6 1996−97 1.1 1997−98 1.1 1998−99 1.3 1999−00 1.5 2000−01 1.3 2001−02 1.5 2002−03 1.9 2003−04 1.4 2004−05 1.1 2005−06 1.5 2006−07 1.6 2007−08 1.8 2008−09 1.7 2009−10 1.3

Vatnajökull 8,100 km2 bs bn mwe a−1 mwe a−1

−0.7 −0.6 −1.3 −1.6 −1.9 −2.5 −2.1 −2.0 −2.3 −2.0 −1.9 −2.6 −2.4 −2.5 −2.3 −2.2 −2.4 −2.0 −3.4

1.3 1.2 0.5 −0.1 −0.3 −1.4 −0.9 −0.7 −0.8 −0.6 −0.4 −0.7 −1.0 −1.4 −0.8 −0.6 −0.6 −0.3 −2.1

P

bn mwe

Langjökull 900 km2P bn bn mwe a−1 mwe

1.3 2.6 3.1 3.0 2.6 1.3 0.3 −0.4 −1.2 −1.8 −2.2 −2.9 −3.9 −5.2 −6.0 −6.6 −7.2 −7.5 −9.6

−1.3 −1.7 −0.7 −0.7 −1.3 −1.7 −1.9 −1.5 −0.9 −1.1 −1.4 −1.8 −0.4 −3.8

−1.3 −3.0 −3.7 −4.5 −5.7 −7.4 −9.3 −10.8 −11.7 −12.8 −14.2 −16.0 −16.4 −20.2

Annual mass balance (Table 1). The mass budget has been monitored annually on Hofsjökull since 1987– 1988 [Jóhannesson, 1997; Adalgeirsdóttir et al., 2003, 2006; Jóhannesson et al., 2013], Vatnajökull since 1991, Langjökull since 1996–1997 [Björnsson et al., 1998, 2002, 2004, Björnsson and Pálsson, 2008], and Drangajökull since 2004 [Sigurdsson, 2006]. Moreover sporadic measurements exist from 1935–1938 [Ahlmann, 1939; Ahlmann and Thorarinsson, 1943], 1966–1968 [Björnsson, 1971] and 1986 [Björnsson, 1988].

1 Institute of Earth Sciences, University of Iceland, Sturlugata 7, 101 Reykjavík, Iceland. 2 Icelandic Meteorological Office, Reykjavík, Iceland 3 CNRS-LEGOS, Toulouse, France

Copyright 2013 by the American Geophysical Union. 0094-8276/13/$5.00

1

Hofsjökull Iceland 890 km2P 11,100 km2 bn bn mwe a−1 mwe Gt a−1 −1.4 −1.4 0.5 −0.9 −0.5 −1.4 −1.4 −2.8 1.0 −1.7 −14.0 0.4 −1.4 −11.7 −0.5 −1.8 −3.4 −1.0 −2.8 2.7 −1.5 −4.4 6.4 −1.6 −5.9 14.8 −1.3 −7.3 11.3 −1.0 −8.2 7.8 −1.5 −9.7 9.6 −1.7 −11.4 8.3 −1.1 −12.5 6.2 −1.6 −14.1 9.6 −1.9 −16.1 11.9 −0.6 −16.7 13.3 −0.9 −17.6 9.0 −1.2 −18.8 7.4 −1.2 −19.9 8.4 −0.6 −20.6 3.4 −3.2 −23.7 25.3

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BJRNSSON ET AL.: MASS LOSS FROM ICELANDIC ICE CAPS

Table 2. Average specific mass balance for eight Icelandic ice masses estimated by subtraction of surface elevation maps from different points in time during the 20th century. Glacier Eyjafjallajökull Tindfjallajökull Torfajökull Langjökull

Hofsjökull Drangajökull Snæfellsjökull Hoffellsjökull

Period 1984–1998 1998–2004 2004–2010 2004–1998 1998–2004 2004–2011 1979–1998 1998–2004 2004–2011 1937–1945 1945–1986 1986–1997 1997–2004 1997–2004 1997–2009 1986 -1999/2001 1999/2001–2004 2004–2008 ∼1990–2011 1999–2008 2001–2010

Mass balance mwe a−1 +0.20 ±0.15 −1.53 ±0.15 -0.90 ±0.15 0.00 ±0.10 −1.60 ±0.15 −1.10 ±0.15 −0.20 ±0.10 −1.80 ±0.20 −1.98 ±0.20 −1.56 ±0.50 −0.31 ±0.10 −0.21 ±0.20 −1.32 ±0.20 −1.36 ±0.20 −1.26 ±0.15 −0.42 ±0.20 −1.44 ±0.30 −1.08 ±0.20 −0.35 ±0.10 −1.4 ±0.10 −1.2 ± 0.10

Long-term volume changes. Digital elevation models were constructed based on topographic maps from 1935–1937, 1945–1946, 1960s, and 1980s, by photogrammetry, trigonometric geodetic and DGPS surveys after 1980 [Björnsson, 1988; Björnsson and Pálsson, 2008; Pálsson et al., 2012; Adalgeirsdóttir et al., 2011], various satellite images (SAR Tandem, 1995–1996 and EMISAR 1998; [Magnússon et. al., 2005a,b]; ASTER (after 2000), SPOT5-HRS and HRG optical images, since 2002 [Berthier et al., 2005; Gudmundsson et al., 2009, 2011] and airborne LiDAR since 2007, [Jóhannesson et al., 2011, 2013]. The average annual specific net mass balance is derived from estimated of volume change over the entire glacier dividing by the number of years. Changes in the glacier surface elevation assumed to reflect changes in the volume of glacier ice of density 900 kg m−3 . Error analysis were discussed in Gudmundsson et al., [2011] Pálsson et al., [2012] and Berthier et al., [2005].

BJRNSSON ET AL.: MASS LOSS FROM ICELANDIC ICE CAPS

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