Glacier Retreat in Iceland Mapped from Space: Time Series Analysis of Geodata from 1941 to 2018

Abstract

In recent decades, glaciers outside Greenland and Antarctica have shown increasingly rapid rates of mass loss and retreat of the ice front, which is associated with climatic and oceanic warming. Due to their maritime location, Icelandic glaciers are sensitive to short-term climate fluctuations and have shown rapid rates of retreat and mass loss over the last decade. In this study, historical maps (1941–1949) of the US Army Map Service (AMS series C762) and optical satellite imagery (Landsat 1, Landsat 5, Landsat 7, Landsat 8, and Sentinel-2) are used to study the Langjökull, Hofsjökull and Vatnajökull ice caps. By the help of the Normalized Difference Snow Index (NDSI), the glacier terminus fluctuations of the ice caps from 1973 to 2018 and the Equilibrium Line Altitude (ELA) from 1973 to 2018 are analyzed. The results are compared with climate data, especially with mean summer temperatures and winter precipitation. Due to the negative temperature gradient with increasing altitude, bivariate histograms are generated, showing the glaciated area per altitude zone and time, and providing a prediction of the future development until 2050 and beyond. The results indicate that Langjökull, Hofsjökull and Vatnajökull are retreating and advancing over the study period in correlation with the mean summer temperature, with a steady decrease over time being the clearest and most significant trend. The lower parts of the glaciers, thus, will probably disappear during the next decades. This behaviour is also evident by an exceptional increase of the ELA observed on all three glaciers, which leads to a reduction of the accumulation zone.

Geophysical reconstruction of the late Holocene proximal proglacial landsystem at Skeiðarársandur, southeast Iceland

“…Fig. 8) can be attributed to a greater sediment flux available due to a longer periood of coupling of the glacier and sandur surface (Hannesdóttir et al ., 2020; Hauser and Schmitt, 2021). In addition, sediment flux as a result of subglacially‐induced jökulhlaups, following the reactivation of Grímsvötn in 1783 (Guðmundsson, 1992), disproportionately affected eastern portions of Skeiðarársandur compared to the central and western sections of the sandur.…”

“…Thickness of the deposits above PR1 are greatest in more eastern locations where Skeiðarárjökull has retreated from its LIA maximum at a much slower rate than in more central and western sandur locations (e.g. Hannesdóttir et al ., 2020; Hauser and Schmitt, 2021). We can attribute the majority of aggradation above PR1 to be due to jökulhlaup‐related deposition when Skeiðarárjökull was advanced and coupled to the sandur surface.…”

“…Thickness of the deposits above PR1 are greatest in more eastern locations where Skeiðarárjökull has retreated from its LIA maximum at a much slower rate than in more central and western sandur locations (e.g. Hannesdóttir et al ., 2020; Hauser and Schmitt, 2021).…”

Observed and Predicted Trends in Icelandic Snow Conditions for the period 1930–2100

“…Most of these areas have experienced an increase in SCF, especially the eastern highlands and the mountainous regions of Northern and Northwestern Iceland. A few areas showed significant decreases in the SCF and most of those were located at the termini of the country's major outlet glaciers, whose retreat has been well documented (Aðalgeirsdóttir et al, 2020;Hannesdóttir et al, 2019;Hauser & Schmitt, 2021) or in coastal areas. All manned observations sites where a decrease in SCF or SND had occurred over the period were all located at low elevation in coastal areas except for one.…”

Estimating local surface glacier mass balance from migration of the 1918 Katla eruption tephra layer on Sléttjökull, southern Iceland

“…Glacier retreat is a global phenomenon and since the 1990s, it is very likely caused by the warming of the atmosphere due to human activities (IPCC, 2021). On the three largest Icelandic glaciers, the equilibrium line altitude has risen by more than 200 m since 1973 (Hauser and Schmitt, 2021). In the period 1890-2019, the volume of Icelandic glaciers was reduced by 16% to ∼3400 km 3 (Aðalgeirsdóttir and others, 2020).…”