a−1, while the corresponding number for Hofsjökull and Langjökull is determined to be 0.07 m w.e. Opin. Mass loss from Icelandic glaciers in the years 1994/5–2009/10 was reported as 9.5 ± 1.5 Gt a−1 with a large interannual variability (Björnsson et al., 2013). Evolution of the Norwegian plateau icefield Hardangerjøkulen since the “little ice age”. The mass balance year 2014/15 was characterized by a long sequence of low-pressure systems arriving one after another through the winter, bringing large amounts of precipitation, followed by a cool summer with little melt, resulting in positive mass balance on all the glaciers. Glacier mass loss is a global phenomenon, and the rates in the early 21st century are unprecedented for the observed period (Zemp et al., 2015). Atmosphere 9, 450. doi:10.3390/atmos9110450, Schuler, T. V., Kohler, J., Elagina, N., Hagen, J. O. M., Hodson, A. J., Jania, J. Earth Sci. The town Stykkishólmur is shown with a purple dot, from which a temperature record exists since the middle of the 19th century. The animation at the top of this page shows a wide view of Pine Island Glacier (PIG) and the long-term retreat of its ice front. A., et al. Cryosphere 10, 159–177. (7) Estimates of the volumes of Vatnajökull and Hofsjökull in 1890 and 1945 as well as the volume of Langjökull in 1890 based on the volume–area scaling (Bahr et al., 1997; Bahr et al., 2015) (Figure 4). Icelandic glaciers. The sounds of the glacier calving is totally awesome. In this article, we present an updated and extended record for the hydrological years 1890/91 to 2018/19. J. Glaciol. The study shows a total mass change of −540 ± 130 Gt (−4.2 ± 1.0 Gt a−1 on average) since the end of the LIA (∼1890), which corresponds to a 16 ± 4% loss of the LIA maximum ice mass. (2019). The calving was caused by ice above the water melting, putting pressure on ice still under the water. (2020) of 0.055 m w.e. Grennan Milliken 30 October 2019. GA, FP, and EM designed the study, wrote the paper, and made the figures. Reykjavík, Iceland: Icelandic Meteorological Office, 84. Each method may have a constant bias, of a similar magnitude to the estimated uncertainties; the probability of the minimum mass change occurring for all periods (or alternatively maximum mass change for all periods) is, however, smaller. FIGURE 1. Res. Remote Sens. 234 (Oslo, Norwegian water resources and energy administration, and Saskatoon, Canada, national hydrology research institute. Present glacier shrinkage, and eustatic changes of sea-level. After 1994/95, an estimate of the annual variability of the mass change for other glaciers than the three largest is included by calculating the net mass change for each glaciological year, using the corresponding F value for each period. Rep., ví 2017-016. (2020); we describe the method below and the resulting mass change rates calculated from the area and volume changes are shown with purple boxes in Figures 3A,B,C. Timescales for redistribution of ice volume to maintain the characteristic shape of a glacier are expected to be much shorter than the response time of the glacier to mass-balance changes (Jóhannesson et al., 1989; Harrison et al., 2001). glacier models is unable to adequately resolve this critical interaction between ice sheets and climate. Mass changes of the Icelandic glaciers have, furthermore, been estimated using ICESat (Nilsson et al., 2015), CryoSat2 (Foresta et al., 2016), and the GRACE satellites (von Hippel and Harig, 2019; Wouters et al., 2019; Ciracì et al., 2020), and Sørensen et al. (2020). a−1. A database of worldwide glacier thickness observations. Since 2010, the mass loss rate has on average been ∼50% lower, with the exception of 2018/19, when one of the highest annual mass losses was observed (mass change rate −15.0 ± 1.6 Gt a−1). J. Glaciol. Dragosics, M., Meinander, O., Jónsdóttir, T., Dürig, T., De Leeuw, G., Pálsson, F., et al. Its future after that will depend on how much warming will be realized (Schmidt et al., 2019). tweet. Footage captured using GoPro Hero 7 Black. Guðmundsson, S., Björnsson, H., Pálsson, F., Magnússon, E., Sæmundsson, Þ., and Jóhannesson, T. (2019). Ann. FIGURE 4. The record shows variability on decadal timescales with a period of near-zero mass balance in the 1980s and early 1990s before the onset of consistently negative mass balance on the order of −1 m a−1 that has prevailed since then. 61, 25–34. Mean specific surface mass-balance records of the three largest glaciers in Iceland obtained with glaciological method (in situ surveys). Ice calving, also known as glacier calving or iceberg calving, is the breaking of ice chunks from the edge of a glacier. Holocene and latest Pleistocene climate and glacier fluctuations in Iceland. Using volume–area scaling to estimate changes in the volume of glaciers with a well-known subglacial topography, from variations in glacier area over decadal time spans, may be expected to be more accurate because this mainly relies on the assumption that the glacier maintains a similar shape as it responds to mass-balance variations with changes in its area and volume. These include the following: (1) Record of the annual surface mass balance obtained with the glaciological method for the three largest ice caps, Vatnajökull (glaciological years 1991/92 to 2018/19), Hofsjökull (1987/88 to 2018/19), and Langjökull (1996/97 to 2018/19). : Earth Surface. doi:10.1038/s41586-019-1071-0. On those timescales, this study does not clearly indicate periods of substantially positive mass balance. The total height of the ice was about 915 m (3,000 … Thus, uncertainty about the overall magnitude of the volume of the glacier in question does not affect the accuracy of the estimated volume changes in this case. Res. These studies are based on mass-balance models that do not take non-surface mass balance into account and they therefore have a tendency to underestimate the future glacier decline. doi:10.5194/tc-11-1665-2017, Schmidt, L. S., Aðalgeirsdóttir, G., Pálsson, F., Langen, P. L., Guðmundsson, S., and Björnsson, H. (2019). (2004). The figure shows only the period when Vatnajökull, Hofsjökull, and Langjökull have all been monitored with glaciological observations. 54, 63–74. Front. (2017) showed that signal leakage due to mass changes of the neighboring Greenland Ice Sheet and the effect of glacial isostatic rebound need to be carefully taken into account. The record spans 129 years, although the annual variability is not available until the last two decades of the 20th century. Volcanol. NHRI science. A part of this non-surface mass balance is caused by calving activity, which was insignificant in the first half of the 20th century, but has been gradually increasing with the ongoing retreat of the outlet glaciers located in over-deepened troughs (Guðmundsson et al., 2019). The rate in the rapid downwasting period 1994/95–2018/19 is −9.6 ± 0.8 Gt a−1. At Bowdoin Glacier, Northwest Greenland, most calving occurs by a few large events resulting from kilometre-scale fractures forming parallel to the calving front. As a fraction of the typical magnitude of the surface mass balance (∼−1 m w.e. “Geographic names of Iceland’s glaciers,” in Historic and modern (Washington: U.S. Geological Survey Professional Paper), 1746. 111, F03001. Quat. The non-surface mass balance is known to be a non-negligible component of the mass balance of glaciers in Iceland (e.g., Björnsson et al., 2013) but has so far not been included in mass-balance estimates. 35, 355–369. [Dataset]. (2013). Mass balance of western and northern Vatnajökull, Iceland, 1991–1995. For the periods of assumed zero mass balance of Vatnajökull in 1970/71 to 1979/80 and Hofsjökull in 1970/71 to 1986/87, the assigned uncertainty is 0.20 m w.e. 40, 1–5. The results of von Hippel and Harig (2019) are not corrected for isostatic rebound and the mass loss rate of Ciracì et al. doi:10.1177/0959683619865601, Wittmann, M., Zwaaftink, C. D. G., Schmidt, L., Guðmundsson, S., Pálsson, F., Arnalds, O., et al. Right: (F) Cumulative specific mass balance (m w.e.) Based on these comparsions, the uncertainties for the decadal averages for specific mass balance of Vatnajökull during the observed and modeled periods is determined to be 0.1 m w.e. Radio-echo soundings on Icelandic temperate glaciers: history of techniques and findings. 66, 46–65. Surface and bedrock topography of ice caps in Iceland, mapped by radio echo-sounding. J. Geosci. doi:10.5194/tc-14-1043-2020, Keywords: mass balance, glaciers, climate, Iceland, glacier–climate relationship, Citation: Aðalgeirsdóttir G, Magnússon E, Pálsson F, Thorsteinsson T, Belart JMC, Jóhannesson T, Hannesdóttir H, Sigurðsson O, Gunnarsson A, Einarsson B, Berthier E, Schmidt LS, Haraldsson HH and Björnsson H (2020) Glacier Changes in Iceland From ∼1890 to 2019. doi:10.5194/tc-9-139-2015, Østby, T. I., Schuler, T. V., Hagen, J. O., Hock, R., Kohler, J., and Reijmer, C. H. (2017). 8, 11–18. Many glaciers started retreating from an advanced position near their LIA terminal moraines in the last decades of the 19th century, even if they reached the absolute maximum extent somewhat earlier. Björnsson, H., Pálsson, F., and Guðmundsson, M. T. (2000). Reconciling Svalbard glacier mass balance. Ann. Two of us skated, while the oth… sms. Björnsson, H., and Pálsson, F. (2020). Ann. The response of Hofsjökull and southern Vatnajökull, Iceland, to climate change. Dust and tephra from volcanic eruptions are blown around in the highlands in dry periods and are often deposited on the glaciers, enhancing the melt (Wittmann et al., 2017). We thank three reviewers and the scientific editor Michael Zemp for constructive comments on the manuscript. (2019) extend the record for Icelandic glaciers back to 1950 using mass-balance observations from Storglaciären in Sweden and Storbreen in Norway. doi:10.1080/20014422.1940.11880686, Thorarinsson, S. (1943). Labels by the filled circles indicate dates when both area (Hannesdóttir et al., 2020) and volume are well established, while labels beside stars indicate dates of well-known area, with volume estimated from the deduced volume–area relation (dotted gray line). Our study thus shows that Scandinavian glaciers are not representative of glacier mass change in Iceland. due to how CO is calculated in 1890/91 to 1944/45 with the ratio F (as described above). Iceland is located in a region of maritime climate in the middle of the North Atlantic Ocean with relatively cool summers, mild winters, and high precipitation. The calving will continue to increase as the glaciers retreat, and should, along with other non-surface mass-balance components, be taken into account in future projections of mass loss of glaciers in Iceland. (2020) are in the last version of the WGMS database (10.5904/wgms-fog-2020-08). a−1. The surface mass balance from the glaciological method is obtained by measuring the snow water equivalent (w.e.) Zamolo, A. Sensitivity of Vatnajökull ice cap hydrology and dynamics to climate warming over the next 2 centuries. They neither reflect random annual errors in those records, nor annual deviation from long-term means for the geodetic and volume–area scaling results. Afkomumælingar á Hofsjökli 1988–2017 (mass balance Measurements on Hofsjökull 1988–2017). Nat. 5, 427–432. To estimate the maximum glacier volume at the end of the LIA, a volume–area scaling method is used based on the observed area and volume from the three largest ice caps (over 90% of total ice mass) at 5–7 different times each, in total 19 points. The surface mass-balance record obtained with the glaciological method for Langjökull (in 1997/98–2003/04) has been compared with volume changes derived from geodetic mass-balance estimates (Pálsson et al., 2012). 1). We apply a variable calving rate as described by Jóhannesson et al. doi:10.5194/tc-9-565-2015, Hannesdóttir, H., Björnsson, H., Pálsson, F., Aðalgeirsdóttir, G., and Guðmundsson, S. (2015b). Geosci. Surface and bedrock topography of the Mýrdalsjökull ice cap, Iceland: the Katla caldera, eruption sites and routes of jökulhlaups. The continued mass loss is dependent on future greenhouse gas emissions and whether, and if so how rapidly, they will be reduced. Received: 18 January 2019 – Discussion started: 7 February 2019 Revised: 23 May 2019 – Accepted: 6 June 2019 – Published: 28 June 2019 Abstract. 25, 1–54. The GRACE record (Wouters et al., 2019) has some years (e.g., 2006/07 and 2010/11) with more negative mass change, and others (e.g., 2005/06, 2011/12, and 2013/14) are less negative than our estimates, although the data points from our record are within the large uncertainty range of the GRACE values. Geophys. Cryosphere 5, 961–975. Change. The method is found to be uncertain by tens of per cent, up to even a factor 2–3, for estimating the volume of ice caps with an unknown subglacial topography (Gärtner-Roer et al., 2014), and methods that include information on glacier mass balance and glacier-surface geometry using ice-flow dynamics (Huss and Farinotti, 2012; Farinotti et al., 2019) are preferred for this purpose. Modelling the 20th and 21st century evolution of Hoffellsjökull glacier, SE-Vatnajökull, Iceland. Sørensen, L. S., Jarosch, A. H., Aðalgeirsdóttir, G., Barletta, V. R., Forsberg, R., Pálsson, F., et al. 209, 226–233. The inventory of Icelandic glaciers made around the year 2000 includes about 300 glaciers (Sigurðsson and Williams, 2008). Mass balance of Mýrdalsjökull ice cap accumulation area and comparison of observed winter balance with simulated precipitation. The corresponding minimum and maximum volume estimates for Vatnajökull in 1945 and 1890 (shown with error bars in Figure 4) are larger than the volumes estimated for the LIA maximum area (1890 star in Figure 4) and the doubled area correction due to surges (1890** star in Figure 4). A comparison of our results to the annual mass change rates of Zemp et al. a−1 in 1996/97 and use −0.067 m w.e. The results presented here add valuable information to global estimates of the response of glaciers to climate change in the past several decades. Res. Therefore, the observed difference may partly be due to the lack of seasonal correction (that could be 5–20% of typical summer melt) when estimating the geodetic mass balance. Surges of glaciers in Iceland. The mass change record of all glaciers in Iceland is shown in Figure 5. Jökull 639, 200929. doi:10.33799/jokull2020.70.001, Harrison, W. D., Elsberg, D. H., Echelmeyer, K. A., and Krimmel, R. M. (2001). The calving will continue to increase as the glaciers retreat, and should, along with other non-surface mass-balance components, be taken …