Jökull - 01.01.2020, Blaðsíða 4

Reviewed research article
A national glacier inventory and variations in glacier extent in
Iceland from the Little Ice Age maximum to 2019
Hrafnhildur Hannesdóttir1, Oddur Sigurðsson1, Ragnar H. Þrastarson1,
Snævarr Guðmundsson3, Joaquín M.C. Belart2,4, Finnur Pálsson2, Eyjólfur Magnússon2,
Skúli Víkingsson5, Ingibjörg Kaldal5 and Tómas Jóhannesson1
1Icelandic Meteorological Office (IMO), Bústaðavegur 7–9, IS-108 Reykjavík, Iceland; e-mail: hh@vedur.is
2Institute of Earth Sciences, University of Iceland (IES-UI), Sturlugata 7, IS-102 Reykjavík, Iceland
3South East Iceland Nature Research Center (SEINRC), Litlabrú 2, IS-780 Höfn, Iceland
4Laboratoire d’Etudes en Géophysique et Océanographie Spatiales, Université de Toulouse,
Avenue Edouard Belin, 31400 Toulouse, France
5Iceland Geosurvey (ÍSOR), Grensásvegur 9, IS-108 Reykjavík, Iceland
https://doi.org/10.33799/jokull2020.70.001
Abstract — A national glacier outline inventory for several different times since the end of the Little Ice Age
(LIA) in Iceland has been created with input from several research groups and institutions, and submitted to the
GLIMS (Global Land Ice Measurements from Space, nsidc.org/glims) database, where it is openly available.
The glacier outlines have been revised and updated for consistency and the most representative outline chosen.
The maximum glacier extent during the LIA was not reached simultaneously in Iceland, but many glaciers
started retreating from their outermost LIA moraines around 1890. The total area of glaciers in Iceland in 2019
was approximately 10,400 km2, and has decreased by more than 2200 km2 since the end of the 19th century
(corresponding to an 18% loss in area) and by approximately 750 km2 since ∼2000. The larger ice caps
have lost 10–30% of their maximum LIA area, whereas intermediate-size glaciers have been reduced by up to
80%. During the first two decades of the 21st century, the decrease rate has on average been approximately
40 km2 a−1. During this period, some tens of small glaciers have disappeared entirely. Temporal glacier
inventories are important for climate change studies, for calibration of glacier models, for studies of glacier
surges and glacier dynamics, and they are essential for better understanding of the state of glaciers. Although
surges, volcanic eruptions and jökulhlaups influence the position of some glacier termini, glacier variations
have been rather synchronous in Iceland, largely following climatic variations since the end of the 19th century.
INTRODUCTION
Most glaciers in the world have retreated from
their advanced positions of the Little Ice Age (LIA,
∼1450–1900 in Iceland), which they reached at dif-
ferent times (e.g. Grove, 2004). There is a robust
trend of shrinkage and volume loss of glaciers in
all glacierized regions of the Earth (Paul and Bolch,
2019; Zemp et al., 2019). The LIA outer boundary
is often marked by terminal and lateral moraines as
well as trimlines, which have been used to reconstruct
the maximum LIA extent of glaciers (e.g. Paul and
Bolch, 2019). Reconstructions of glacier extents from
a variety of sources such as historical documents, pic-
torial sources, delineation and dating of moraines and
lacustrine records have revealed a detailed timeline of
glacier variations during the LIA for many glaciers
in the Alps (e.g. Zemp et al., 2008), South Amer-
ica (e.g. Masiokas et al., 2009; Zalazar et al., 2020),
Norway (e.g. Nesje et al., 2008; Nussbaumer et al.,
2011) and Iceland (e.g. Þórarinsson, 1943; Björns-
son and Pálsson, 2004; Bradwell et al., 2006; Sig-
urðsson, 2010; Aðalgeirsdóttir et al., 2011; Pálsson
JÖKULL No. 70, 2020 1