Spatially distributed mass balance of 14 Icelandic glaciers, 1945−2017. Trends and link with climate

Excluding the three largest ice caps, Icelandic glaciers have, until recently, received limited attention in terms of mass balance observations over the last century. In this study, mass balance estimates from 1945 to 2017 are presented, in decadal time spans, for 14 glaciers (total area 1054 km2) subject to different climatic forcing in Iceland. The mass balances are derived from airborne and spaceborne stereo imagery and airborne lidar, and correlated with precipitation and air temperature by a first order equation including a reference-surface correction term. This permits statistical modelling of annual mass balances and to temporally homogenize the mass balances for a region-wide, multidecadal mass balance study. The mean (standard deviation) mass balances of the target glaciers were −0.43 (0.17) m w.e. a−1 in 1945−1960, 0.01 (0.21) m w.e. a−1 in 1960−1980, 0.10 (0.23) m w.e. a−1 in 1980−1994, −0.98 (0.44) m w.e. a−1 in 1994−2004, −1.23 (0.57) m w.e. a−1 in 2004−2010 and 0.06 (0.35) m w.e. a−1 in 2010−2017. The majority of mass loss occured in 1994−2010, accounting for 22.5±1.6 Gt (1.4±0.1 Gt a−1). High decadal mass-balance variability is found on glaciers located at the south and west coasts,in contrast to the glaciers located inland, north and northwest. These patterns are likely explained by the proximity to warm (south and west) versus cold (northwest) oceanic currents.