Modelling the 20th and 21st century evolution of Hoffellsjökull glacier, SE-Vatnajökull, Iceland

Abstract

The Little Ice Age maximum extent of glaciers in Iceland was reached about 1890 AD and most glaciers in the country have retreated during the 20th century. A model for the surface mass balance and the flow of glaciers is used to reconstruct the 20th century retreat history of Hoffellsjökull, a south-flowing outlet glacier of Vatnajökull, which is located close to the southeast coast of Iceland. The bedrock topography was surveyed with radio-echo soundings in 2001. A wealth of data are available to force and constrain the model, e.g. surface elevation maps from ~1890, 1936, 1946, 1986, 2001, 2008 and 2010, mass balance observations conducted in 1936–1938 and after 2001, energy balance measurements after 2001, and glacier surface velocity derived by DGPS and correlation of SPOT5 images. The 21% volume loss of this glacier in the period 1895–2010 is realistically simulated with the model. After calibration of the model with past observations, it is used to simulate the future response of the glacier during the 21st century. The mass balance model was forced with an ensemble of temperature and precipitation scenarios from a study of the effect of climate change on energy production in the Nordic countries (the CES project). If the average climate of 2000–2009 is maintained into the future, the volume of the glacier is projected to be reduced by 30% with respect to the present at the end of this century, and the glacier will almost disappear if the climate warms as suggested by most of the climate change scenarios. Runoff from the glacier is predicted to increase for the next 30–40 years and decrease after that as a consequence of the diminishing ice-covered area

Variations of southeast vatnajökull ice cap (iceland) 1650–1900 and reconstruction of the glacier surface geometry at the little ice age maximum

“…) and Hólar in Hornafjörður (Aðalgeirsdóttir et al . ) during most of the nineteenth century, with a closer correlation in the twentieth century (Fig. e).…”

“…The average summer temperature during the time period 1860–1890 at Hólar in Hornafjörður (partly reconstructed from other temperature records; Aðalgeirsdóttir et al . ) was 8.5°C compared with an average of 10.5°C during the time period 2000–2010. Assuming a temperature lapse rate of 0.0065°C m –1 , the ELA at the time of formation of the uppermost lateral moraines would have been approximately 310 m lower on average than today.…”

“…) and Hoffellsjökull (Björnsson and Pálsson ; Aðalgeirsdóttir et al . ), which are not included in this study, are shown in Table and the LIA surface reconstruction in Fig. .…”

“…) and the 7‐year running average temperature at Hólar in H ornafjörður ( I celandic M eteorological O ffice, A ðalgeirsdóttir et al . ) and reconstructed northern hemisphere ( NH ) temperatures (dark gray) calculated by combining low‐resolution proxies with tree‐ring data ( M oberg et al . ), and a temperature reconstruction from G reenland (light gray), based on an average of uplift corrected δ 18 O data from A gassiz and R enland ( V inther et al .…”

Contemporary glacigenic inputs to the dust cycle

“…Dust emission areas may also change depending on which sectors of the outwash plains remain active. On large ice caps and ice sheets individual outlet glaciers may undergo retreat and associated increase in runoff on shorter timescales (Aðalgeirsdóttir et al, 2011).…”