Jökull - 01.01.2020, Qupperneq 16

Glacier extent in Iceland, 1890–2019
Figure 4: The extent of Vatnajökull ice cap, Tungnafellsjökull and the glaciers of Mt. Snæfell at several times since the LIA
maximum in ∼1890. Mj=Morsárjökull, Skj=Skaftafellsjökull, Svj=Svínafellsjökull, Kvj=Kvíárjökull. – Útlínur Vatnajök-
uls, Tungnafellsjökuls og jöklanna á Snæfelli á mismunandi tímum frá því um 1890.
Breiðamerkurjökull calves into Jökulsárlón glac-
ier lagoon, which started to form in the mid-1930s
because of the retreat of the glacier in a subglacial
valley that reaches below sea level. This ∼900 km2
outlet glacier retreats and thins due to negative sur-
face mass balance in a warming climate, but calving
causes approximately one-third of the mass loss (Páls-
son, 2018). The southern outlet glaciers have retreated
up to several km since the end of the 19th century
(Figure 4), with the maximum retreat of more than
8 km of Breiðamerkurjökull.
Surges of Dyngjujökull and Brúarjökull (Björns-
son et al., 2003) have influenced the configuration
of the northern glacier margin, with the most exten-
sive advance of 10 km during the surge of Brúarjök-
ull in 1890 (Þórarinsson, 1964). Brúarjökull retreated
11 km between 1890 and 1963, and the glacier again
advanced close to 10 km during the surge in 1963–
1964 (Guðmundsson et al., 1996). Thus, the glacier
outline in 1973 was close to the outermost moraines
of ∼1890 (Figure 4).
The LIA extent of the southern outlet glaciers
of Vatnajökull has been traced in detail (Bradwell et
al., 2006; Guðmundsson et al., 2012, 2017; Hann-
esdóttir et al., 2015a; Everest et al., 2017). Less
detailed information about the LIA extent is avail-
able for other parts of the ice cap; however, a few
notes from travellers and natural scientists visiting
the glacier termini give some indications. Skeiðar-
árjökull fluctuated near it maximum LIA extent un-
til ca. 1890. A surge in 1929 brought at least parts
of the terminus beyond the previous maximum extent
JÖKULL No. 70, 2020 13