20Satellite imagery is increasingly used to monitor glacier area changes and create glacier inventories. 21Robust and efficient pixel-based band ratios have proven to be accurate for automatically delineating 22 clean glacier ice, however such classifications are restricted by debris-covered ice due to its spectral 23 similarity with surrounding terrain. Object-Based Image Analysis (OBIA) has emerged as a new 24 analysis technique within remote sensing. It offers many advantages over pixel-based classification 25 techniques due to the ability to work with multiple data sources and handle data contextually and 26 hierarchically. By making use of OBIA capabilities we automatically classify clean ice and debris-27 covered ice in the challenging area surrounding Mount Manaslu in Nepal using optical (Landsat 8), 28 topographic (void-filled SRTM) and SAR coherence (ALOS PALSAR) data. Clean ice was classified with 29 a mean accuracy of 93.3% while debris-covered ice was classified with an accuracy of 83.3% when 30 compared to manually corrected outlines, providing a total glacier accuracy of 91%. With further 31 developments in the classification, steep tributary sections of ice could be contextually included, 32 raising the accuracy to over 94%. One prominent advantage of OBIA is that it allows some post-33 processing and correction of the glacier outlines automatically, reducing the amount of manual 34 correction needed. OBIA incorporating SAR coherence data can be recommended for future mapping 35 of debris-covered ice. 36

This study assesses changes in glacier area, velocity, and geodetic mass balance for the glaciers in the Manaslu region of Nepal, a previously undocumented region of the Himalayas. We studied changes between 1970 (for select glaciers), 2000, 2005, and 2013 Glacier change varies across the region and seems to relate to a combination of glacier hypsometry, glacier elevation range and the presence and distribution of supraglacial debris. Lower-elevation, debris-free glaciers with bottom-heavy hypsometries are losing most mass. As the glaciers in the Manaslu region continue to stagnate, an accumulation and thickening of the debris-cover is likely, thereby insulating the glacier and further complicating future glacier responses to climate.

Abstract. Glaciers and rock glaciers play an important role in the hydrology of the semi-arid northern Chile. Several studies show that glaciers have rapidly lost mass in response to climate change during the last decades. The response of rock glaciers to climate change in this region is, however, less known. In this study we use a combination of historical aerial photography, stereo satellite imagery, airborne lidar, and the Shuttle Radar Topography Mission (SRTM) DEM to report glacier changes for the Tapado Glacier–rock glacier complex from the 1950s to 2020 and to report mass balances for the glacier component of the complex, Tapado Glacier. Furthermore, we examine high-resolution elevation changes and surface velocities between 2012 and 2020 for 35 rock glaciers in the La Laguna catchment. Our results show how Tapado Glacier has shrunk by -25.2±4.6 % between 1956 and 2020, while the mass balance of Tapado Glacier has become steadily more negative, from being approximately in balance between 1956 and 1978 (-0.04±0.08 m w.e. a−1) to showing increased losses between 2015 and 2020 (-0.32±0.08 m w.e. a−1). Climatological (re-)analyses reveal a general increase in air temperature, decrease in humidity, and variable precipitation since the 1980s in the region. In particular, the severe droughts starting in 2010 resulted in a negative mass balance of -0.54±0.10 m w.e. a−1 between 2012 and 2015. The rock glaciers within the La Laguna catchment show heterogenous changes, with some sections of landforms exhibiting pronounced elevation changes and surface velocities exceeding that of Tapado Glacier. This could be indicative of high ice contents within the landforms and also highlights the importance of considering how landforms can transition from more glacial landforms to more periglacial features under permafrost conditions. As such, we believe high-resolution (sub-metre) elevation changes and surface velocities are a useful first step for identifying ice-rich landforms.

Holocene fluctuations of a small outlet glacier from the ice cap Høgtuvbreen at 65° N in coastal northern Norway are reconstructed based on distal glacier-fed lake sediments, complemented by a moraine sequence dated by lichenometry. Glaciers respond to changes in accumulation-season precipitation, ablation-season temperature and redistribution of snow by wind. Hence, reconstructions of glacier fluctuations based on distal glacier-fed lakes may give detailed information about past climate at a potentially high temporal resolution. Yet, the importance of any of these climate components is often difficult to solve. Here, we apply the ‘Liestøl-relationship’, which expresses the relationship between ablation-season temperature and annual accumulation of snow at the equilibrium line altitude (ELA), to the reconstructed local temperature–precipitation–wind ELA (TPW-ELA) to infer the relative importance of winter-balance and ablation-season temperature as causes of reconstructed glacier variation. The reconstructions show a large glacier readvance corresponding with the 8.2-ka cold event and a sequence of eight distinct glacier advances and retreats during the Neoglacial time period bracket between 4300 ± 40 cal. yr BP and AD 1900. The glacier reached its Holocene maximum position in AD 1773 ± 29, subsequently followed by an ongoing unprecedented retreat, interrupted only by some minor halts and readvances. Based on a detailed comparison of our results with similar studies of both continental and maritime glaciers, as well as independent temperature proxy records across Scandinavia, we argue that significant and consistent deviations in ELA fluctuations between continental and maritime glaciers in the region are caused by a north–south migration of the arctic polar front. Additionally, we suggest that deviations in ELA fluctuations between Scandinavian maritime and continental glaciers around 7150, 6560, 6000, 5150, 3200 and 2200 cal. yr BP reflect the different response of continental and maritime glaciers to drops in total solar irradiance (TSI).

In an effort to reconstruct past aeolian activity, a foredune stratigraphy and a continuous lake sediment record from the largest dunefield on Andøya, northern Norway, have been investigated. The dunefield extends landwards in a north-eastward direction and consists of several parabolic dunes, foredunes and blowouts. The sediment record (169 cm) from the nearby lake Latjønna and the foredune stratigraphy (10 m) covers the last 6200 and 3700 cal. yr BP, respectively. Both sites possess sediments deposited after the Tapes transgression maximum (~6800 cal. yr BP), which reached a level of ~7–8 m a.s.l. at the study site. The lake sediment record consists of several units dominated by sand grains interspersed by more organic-rich beds. The core has been examined by x-ray fluorescence (XRF), magnetic susceptibility (MS) and loss-on-ignition (LOI). Mineral grains were detected by wet sieving of the ignition residue (IR), and the influx of sand grains to Latjønna was calculated based on the weight of sand grains >250 µm/cm divided by the accumulation rate determined from a radiocarbon (14C)-based age–depth model. Phases with high influx of sand to Latjønna are recorded around 4800, 4250, 3000–2000, 1850–1750, 1600–600, 450, 300 and 150 cal. yr BP, which coincides with periods of increased storminess recorded in other studies around the North-Eastern Atlantic region. The two study sites show, however, quite contrasting results; high sedimentation rates in the lake record associated with greater aeolian influx correspond to stability in the foredune stratigraphy reflected by the presence of several palaeosols. Because of this out-of-phase behaviour, it is suggested that the foredune is mainly influenced by summer climate and relative sea level (RSL) change, whereas the lake record is more influenced by niveo-aeolian processes transporting sand grains farther inland during winter.

Abstract. Glaciers and rock glaciers play an important role in the hydrology of the semi-arid Northern Chile. Several studies show that glaciers have strongly lost mass in response to climate change during the last decades. The response to rock glaciers in this region is, however, much less investigated. In this study we use a combination of historical aerial photography, stereo satellite imagery, airborne LiDAR, and the Shuttle Radar Topography Mission (SRTM) DEM to report glacier changes for the Tapado Glacier-Rock Glacier complex from the 1950s to 2020 and to report mass balances for the glacier component of the complex, Tapado Glacier. Furthermore, we examine high-resolution elevation changes and surface velocities between 2012 and 2020 for 40 rock glaciers in La Laguna catchment. Our results show how the glacier has lost 25.2 ± 4.6 % of its ice covered area between 1956 and 2020, while the mass balance of Tapado Glacier has become steadily more negative, from being approximately in balance between 1956 and 1978 (−0.04 ± 0.08 m w.e. a−1) to showing strong losses between 2015 and 2020 (−0.32 ± 0.08 m w.e. a−1). Climatological (re)-analyses reveal a general increase in air temperature, decrease in humidity, and variable precipitation since the 1980s in the region. In particular the severe droughts in the region starting in 2010 resulted in a particular negative mass balance of −0.54 ± 0.10 m w.e. a−1 between 2012 and 2015. The rock glaciers within La Laguna catchment show heterogenous changes with some sections of landforms exhibiting pronounced elevation changes and surface velocities exceeding that of Tapado Glacier. This could be indicative of high ice contents within the landforms and also highlights the importance of considering how landforms can transition from more glacial landforms to more periglacial features under permafrost conditions. As such, we believe high-resolution (sub-metre) elevation changes and surface velocities are a useful first step for identifying ice-rich landforms.

No abstract

Here we present the first high-resolution late-Holocene glacier record from the Lofoten archipelago in northern Norway. The study is based on analyses of lacustrine sediments from the distal glacier-fed lake Kveitvikvatnet (30.1 m a.s.l.), as well as glacial-geomorphological mapping of the ~4.2-km2 surrounding catchment. The lake sediment cores have been examined for input of glacial-derived sediments by using physical, geochemical and magnetic sediment properties, including x-ray fluorescence (XRF), magnetic susceptibility (MS), grain size analyses, dry bulk density (DBD) and loss-on-ignition (LOI). Former glacier extent has been reconstructed using aerial photography and glacial-geomorphological mapping. Lichenometric dating has been used to construct a moraine chronology covering the recent fluctuations of the largest glacier (back to AD ~1740). AMS radiocarbon dating reveals that the lake sediment record covers the last 1200 years, thereby including both the ‘Little Ice Age’ (LIA) and the ‘Medieval Climate Anomaly’ (MCA). By linking continuously deposited lake sediment proxies of glacier fluctuation to known glacier frontal positions and an independent temperature reconstruction, former fluctuations in the equilibrium-line altitude (ELA) and winter precipitation have been reconstructed. Reconstructed winter precipitation estimates have also been correlated to instrumental data from the region back to AD 1895 and show a remarkable correlation, which further strengthens our approach. We found that both MCA and LIA were periods of substantial glacier variations with respect to the present, with a maximum lowering of the ELA of ~75 and ~85 m, respectively. Increased precipitation during these intervals, associated with more frequent and/or intense winter storms, is suggested to be the major driving force of glacier fluctuations in Lofoten.