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Flor Vermassen - One of the best experts on this subject based on the ideXlab platform.
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A reconstruction of warm-water inflow to Upernavik Isstrøm since 1925 CE and its relation to Glacier Retreat
Climate of the Past, 2019Co-Authors: Flor Vermassen, Nanna Andreasen, David Johannes Wangner, Nicolas Thibault, Marit-solveig Seidenkrantz, Rebecca Jackson, Sabine Schmidt, Kurt H. Kjær, Camilla S. AndresenAbstract:Abstract. The mass loss from the Greenland Ice Sheet has increased over the past 2 decades. Marine-terminating Glaciers contribute significantly to this mass loss due to increased melting and ice discharge. Periods of rapid Retreat of these tidewater Glaciers have been linked to the concurrent inflow of warm Atlantic-sourced waters. However, little is known about the variability of these Atlantic-derived waters within the fjords, due to a lack of multi-annual in situ measurements. Thus, to better understand the potential role of ocean warming on Glacier Retreat, reconstructions that characterize the variability of Atlantic water inflow to the fjords are required. Here, we investigate foraminiferal assemblages in a sediment core from Upernavik Fjord, West Greenland, in which the major ice stream Upernavik Isstrom terminates. We conclude that the foraminiferal assemblage is predominantly controlled by changes in bottom water composition and provide a reconstruction of Atlantic water inflow to Upernavik Fjord, spanning the period 1925–2012. This reconstruction reveals peak Atlantic water influx during the 1930s and again after 2000, a pattern that is comparable to the Atlantic Multidecadal Oscillation (AMO). The comparison of these results to historical observations of front positions of Upernavik Isstrom reveals that inflow of warm Atlantic-derived waters likely contributed to high Retreat rates in the 1930s and after 2000. However, moderate Retreat rates of Upernavik Isstrom also prevailed in the 1960s and 1970s, showing that Glacier Retreat continued despite a reduced Atlantic water inflow, albeit at a lower rate. Considering the link between bottom water variability and the AMO in Upernavik Fjord, and the fact that a persistent negative phase of the AMO is expected for the next decade, Atlantic water inflow into the fjord may decrease in the coming decade, potentially minimizing or stabilizing the Retreat of Upernavik Isstrom during this time interval.
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A reconstruction of warm water inflow to Upernavik Isstrøm since AD 1925 and its relation to Glacier Retreat
Climate of the Past, 2019Co-Authors: Flor Vermassen, Nanna Andreasen, David Johannes Wangner, Nicolas Thibault, Marit-solveig Seidenkrantz, Rebecca Jackson, Sabine Schmidt, Kurt Kjær, Camilla AndresenAbstract:The mass loss from the Greenland Ice Sheet has increased over the past 2 decades. Marine-terminating Glaciers contribute significantly to this mass loss due to increased melting and ice discharge. Periods of rapid Retreat of these tidewater Glaciers have been linked to the concurrent inflow of warm Atlantic-sourced waters. However, little is known about the variability of these Atlantic-derived waters within the fjords, due to a lack of multi-annual in situ measurements. Thus, to better understand the potential role of ocean warming on Glacier Retreat, reconstructions that characterize the variability of Atlantic water inflow to the fjords are required. Here, we investigate foraminiferal assemblages in a sediment core from Upernavik Fjord, West Greenland, in which the major ice stream Upernavik Isstrøm terminates. We conclude that the foraminiferal assemblage is predominantly controlled by changes in bottom water composition and provide a reconstruction of Atlantic water inflow to Upernavik Fjord, spanning the period 1925–2012. This reconstruction reveals peak Atlantic water influx during the 1930s and again after 2000, a pattern that is comparable to the Atlantic Multidecadal Oscillation (AMO). The comparison of these results to historical observations of front positions of Upernavik Isstrøm reveals that inflow of warm Atlantic-derived waters likely contributed to high Retreat rates in the 1930s and after 2000. However, moderate Retreat rates of Upernavik Isstrøm also prevailed in the 1960s and 1970s, showing that Glacier Retreat continued despite a reduced Atlantic water inflow, albeit at a lower rate. Considering the link between bottom water variability and the AMO in Upernavik Fjord, and the fact that a persistent negative phase of the AMO is expected for the next decade, Atlantic water inflow into the fjord may decrease in the coming decade, potentially minimizing or stabilizing the Retreat of Upernavik Isstrøm during this time interval.climate change
Peter O. Bilovitz - One of the best experts on this subject based on the ideXlab platform.
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assembly patterns of soil dwelling lichens after Glacier Retreat in the european alps
Journal of Biogeography, 2017Co-Authors: Juri Nascimbene, Helmut Mayrhofer, Matteo Dainese, Peter O. BilovitzAbstract:Aim To assess the spatial-temporal dynamics of primary succession following deglaciation in soil-dwelling lichen communities. Location European Alps (Austria, Switzerland and Italy). Methods Five Glacier forelands subjected to relevant Glacier Retreat during the last century were investigated. In each Glacier foreland, three successional stages were selected at increasing distance from the Glacier, corresponding to a gradient of time since deglaciation between 25 and 160 years. In each successional stage, soil-dwelling lichens were surveyed within five 1 × 1 m plots. In addition to a classical ecological framework, based on species richness and composition, we applied a functional approach to better elucidate community assembly mechanisms. Results A positive relationship was found between species richness and time since deglaciation indicating that richer lichen communities can be found at increasing terrain ageing. This pattern was associated with compositional shifts, suggesting that different community assemblages can be found along the successional stages. The analysis of β-diversity revealed a significant nested pattern of species assemblages along the gradient (i.e. earlier successional stages hosted a subset of the species already established in older successional stages), while the turnover component was less relevant. Considering functional groups, we found contrasting patterns in relation to time since deglaciation: the incidence of species with a cyanobacterial photobiont and those reproducing by spores decreased, while that of species reproducing by vegetative propagules increased. Main conclusions This study reveals that community assembly patterns of soil-dwelling lichens in alpine Glacier forelands are ruled by mechanisms of directional species accumulation and trait selection that involve a trade-off between different functional strategies. Functional traits that reflect the dispersal and adaptation capability of the species underpin the colonization success of soil-dwelling lichens in Glacier forelands.
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Assembly patterns of soil‐dwelling lichens after Glacier Retreat in the European Alps
Journal of biogeography, 2017Co-Authors: Juri Nascimbene, Helmut Mayrhofer, Matteo Dainese, Peter O. BilovitzAbstract:Aim To assess the spatial-temporal dynamics of primary succession following deglaciation in soil-dwelling lichen communities. Location European Alps (Austria, Switzerland and Italy). Methods Five Glacier forelands subjected to relevant Glacier Retreat during the last century were investigated. In each Glacier foreland, three successional stages were selected at increasing distance from the Glacier, corresponding to a gradient of time since deglaciation between 25 and 160 years. In each successional stage, soil-dwelling lichens were surveyed within five 1 × 1 m plots. In addition to a classical ecological framework, based on species richness and composition, we applied a functional approach to better elucidate community assembly mechanisms. Results A positive relationship was found between species richness and time since deglaciation indicating that richer lichen communities can be found at increasing terrain ageing. This pattern was associated with compositional shifts, suggesting that different community assemblages can be found along the successional stages. The analysis of β-diversity revealed a significant nested pattern of species assemblages along the gradient (i.e. earlier successional stages hosted a subset of the species already established in older successional stages), while the turnover component was less relevant. Considering functional groups, we found contrasting patterns in relation to time since deglaciation: the incidence of species with a cyanobacterial photobiont and those reproducing by spores decreased, while that of species reproducing by vegetative propagules increased. Main conclusions This study reveals that community assembly patterns of soil-dwelling lichens in alpine Glacier forelands are ruled by mechanisms of directional species accumulation and trait selection that involve a trade-off between different functional strategies. Functional traits that reflect the dispersal and adaptation capability of the species underpin the colonization success of soil-dwelling lichens in Glacier forelands.
Camilla Andresen - One of the best experts on this subject based on the ideXlab platform.
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A reconstruction of warm water inflow to Upernavik Isstrøm since AD 1925 and its relation to Glacier Retreat
Climate of the Past, 2019Co-Authors: Flor Vermassen, Nanna Andreasen, David Johannes Wangner, Nicolas Thibault, Marit-solveig Seidenkrantz, Rebecca Jackson, Sabine Schmidt, Kurt Kjær, Camilla AndresenAbstract:The mass loss from the Greenland Ice Sheet has increased over the past 2 decades. Marine-terminating Glaciers contribute significantly to this mass loss due to increased melting and ice discharge. Periods of rapid Retreat of these tidewater Glaciers have been linked to the concurrent inflow of warm Atlantic-sourced waters. However, little is known about the variability of these Atlantic-derived waters within the fjords, due to a lack of multi-annual in situ measurements. Thus, to better understand the potential role of ocean warming on Glacier Retreat, reconstructions that characterize the variability of Atlantic water inflow to the fjords are required. Here, we investigate foraminiferal assemblages in a sediment core from Upernavik Fjord, West Greenland, in which the major ice stream Upernavik Isstrøm terminates. We conclude that the foraminiferal assemblage is predominantly controlled by changes in bottom water composition and provide a reconstruction of Atlantic water inflow to Upernavik Fjord, spanning the period 1925–2012. This reconstruction reveals peak Atlantic water influx during the 1930s and again after 2000, a pattern that is comparable to the Atlantic Multidecadal Oscillation (AMO). The comparison of these results to historical observations of front positions of Upernavik Isstrøm reveals that inflow of warm Atlantic-derived waters likely contributed to high Retreat rates in the 1930s and after 2000. However, moderate Retreat rates of Upernavik Isstrøm also prevailed in the 1960s and 1970s, showing that Glacier Retreat continued despite a reduced Atlantic water inflow, albeit at a lower rate. Considering the link between bottom water variability and the AMO in Upernavik Fjord, and the fact that a persistent negative phase of the AMO is expected for the next decade, Atlantic water inflow into the fjord may decrease in the coming decade, potentially minimizing or stabilizing the Retreat of Upernavik Isstrøm during this time interval.climate change
Maria Shahgedanova - One of the best experts on this subject based on the ideXlab platform.
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Glacier Retreat and climatic variability in the eastern terskey alatoo inner tien shan between the middle of the 19th century and beginning of the 21st century
Global and Planetary Change, 2009Co-Authors: Stanislav Kutuzov, Maria ShahgedanovaAbstract:Abstract Changes in the extent of Glaciers and rates of Glacier termini Retreat in the eastern Terskey–Alatoo Range, the Tien Shan Mountains, Central Asia have been evaluated using the remote sensing techniques. Changes in the extent of 335 Glaciers between the end of the Little Ice Age (LIA; mid-19th century), 1990 and 2003 have been estimated through the delineation of Glacier outlines and the LIA moraine positions on the Landsat TM and ASTER imagery for 1990 and 2003 respectively. By 2003, the Glacier surface area had decreased by 19% of the LIA value, which constitutes a 76 km 2 reduction in Glacier surface area. Mapping of 109 Glaciers using the 1965 1:25,000 maps revealed that Glacier surface area decreased by 12.6% of the 1965 value between 1965 and 2003. Detailed mapping of 10 Glaciers using historical maps and aerial photographs from the 1943–1977 period, has enabled Glacier extent variations over the 20th century to be identified with a higher temporal resolution. Glacial Retreat was slow in the early 20th century but increased considerably between 1943 and 1956 and then again after 1977. The post-1990 period has been marked by the most rapid Glacier Retreat since the end of the LIA. The observed changes in the extent of Glaciers are in line with the observed climatic warming. The regional weather stations have revealed a strong climatic warming during the ablation season since the 1950s at a rate of 0.02–0.03 °C a − 1 . At the higher elevations in the study area represented by the Tien Shan meteorological station, the summer warming was accompanied by negative anomalies in annual precipitation in the 1990s enhancing Glacier Retreat. However, trends in precipitation in the post-1997 period cannot be evaluated due to the change in observational practices at this station. Neither station in the study area exhibits significant long-term trends in precipitation.
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Glacier Retreat and climatic variability in the eastern Terskey–Alatoo, inner Tien Shan between the middle of the 19th century and beginning of the 21st century
Global and Planetary Change, 2009Co-Authors: Stanislav Kutuzov, Maria ShahgedanovaAbstract:Abstract Changes in the extent of Glaciers and rates of Glacier termini Retreat in the eastern Terskey–Alatoo Range, the Tien Shan Mountains, Central Asia have been evaluated using the remote sensing techniques. Changes in the extent of 335 Glaciers between the end of the Little Ice Age (LIA; mid-19th century), 1990 and 2003 have been estimated through the delineation of Glacier outlines and the LIA moraine positions on the Landsat TM and ASTER imagery for 1990 and 2003 respectively. By 2003, the Glacier surface area had decreased by 19% of the LIA value, which constitutes a 76 km 2 reduction in Glacier surface area. Mapping of 109 Glaciers using the 1965 1:25,000 maps revealed that Glacier surface area decreased by 12.6% of the 1965 value between 1965 and 2003. Detailed mapping of 10 Glaciers using historical maps and aerial photographs from the 1943–1977 period, has enabled Glacier extent variations over the 20th century to be identified with a higher temporal resolution. Glacial Retreat was slow in the early 20th century but increased considerably between 1943 and 1956 and then again after 1977. The post-1990 period has been marked by the most rapid Glacier Retreat since the end of the LIA. The observed changes in the extent of Glaciers are in line with the observed climatic warming. The regional weather stations have revealed a strong climatic warming during the ablation season since the 1950s at a rate of 0.02–0.03 °C a − 1 . At the higher elevations in the study area represented by the Tien Shan meteorological station, the summer warming was accompanied by negative anomalies in annual precipitation in the 1990s enhancing Glacier Retreat. However, trends in precipitation in the post-1997 period cannot be evaluated due to the change in observational practices at this station. Neither station in the study area exhibits significant long-term trends in precipitation.
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Climate Change, Glacier Retreat, and Water Availability in the Caucasus Region
Threats to Global Water Security, 2009Co-Authors: Maria Shahgedanova, Wilfried Hagg, D. Hassell, Chris R. Stokes, Viktor PopovninAbstract:The paper discusses the observed and projected warming in the Caucasus region and its implications for Glacier melt, water availability and potential hazards. A strong positive trend in summer air temperatures of 0.05 degrees C year(-1) is observed in the high-altitude areas (above 2000 m) providing for a strong Glacier melt. A widespread Glacier Retreat has also been reported between 1985 and 2000, with an average rate of 8 m year(-1). A warming of 5-7 degrees C is projected for the Sum mer months in the 2071-2100 period under the A2 emission group of scenarios, Suggesting that enhanced Glacier melt and a changing water balance can be expected.
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An Assessment of the Recent Past and Future Climate Change, Glacier Retreat, and Runoff in the Caucasus Region Using Dynamical and Statistical Downscaling and HBV-ETH Hydrological Model
Regional Aspects of Climate-Terrestrial-Hydrologic Interactions in Non-boreal Eastern Europe, 2009Co-Authors: Maria Shahgedanova, Wilfried Hagg, Martina Zacios, Viktor PopovninAbstract:The paper discusses the observed and projected warming in the Caucasus region and its implications for Glacier melt and runoff. A strong positive trend in summer air temperatures of 0.05 degrees C a(-1) is observed in the high-altitude areas providing for a strong Glacier melt and continuous decline in Glacier mass balance. A warming of 4-7 degrees C and 3-5 degrees C is projected for the summer months in 2071-2100 under the A2 and B2 emission scenarios respectively, suggesting that enhanced Glacier melt can be expected. The expected changes in winter precipitation will not compensate for the summer melt and Glacier Retreat is likely to continue. However, a projected small increase in both winter and summer precipitation combined with the enhanced Glacier melt will result in increased summer runoff in the currently glaciated region of the Caucasus (independent of whether the region is glaciated at the end of the twenty-first century) by more than 50% compared with the baseline period.
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Recent Glacier Retreat in the Caucasus Mountains, Russia, and associated increase in supraglacial debris cover and supra-/proglacial lake development
Annals of Glaciology, 2007Co-Authors: Chris R. Stokes, Viktor Popovnin, A. Aleynikov, Stephen D. Gurney, Maria ShahgedanovaAbstract:This paper reports changes in supraglacial debris cover and supra-/proglacial lake development associated with recent Glacier Retreat (1985-2000) in the central Caucasus Mountains, Russia. Satellite imagery (Landsat TM and ETM+) was used to map the surface area and supraglacial debris cover on six neighbouring Glaciers in the Adylsu valley through a process of manual digitizing on a false-colour composite of bands 5, 4, 3 (red, green, blue). The distribution and surface area of supraglacial and proglacial lakes was digitized for a larger area, which extended to the whole Landsat scene. We also compare our satellite interpretations to field observations in the Adylsu valley. Supraglacial debris cover ranges from 25% on individual Glaciers, but Glacier Retreat between 1985 and 2000 resulted in a 3-6% increase in the proportion of each Glacier covered by debris. The only exception to this trend was a very small Glacier where debris cover did not change significantly and remote mapping proved more difficult. The increase in debris cover is characterized by a progressive up- Glacier migration, which we suggest is being driven by focused ablation (and therefore Glacier thinning) at the up-Glacier limit of the debris cover, resulting in the progressive exposure of englacial debris. Glacier Retreat has also been accompanied by an increase in the number of proglacial and supraglacial lakes in our study area, from 16 in 1985 to 24 in 2000, representing a 57% increase in their cumulative surface area. These lakes appear to be impounded by relatively recently lateral and terminal moraines and by debris deposits on the surface of the Glacier. The changes in Glacier surface characteristics reported here are likely to exert a profound influence on Glacier mass balance and their future response to climate change. They may also increase the likelihood of Glacier-related hazards (lake outbursts, debris slides), and future monitoring is recommended.
Sabine Schmidt - One of the best experts on this subject based on the ideXlab platform.
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A reconstruction of warm-water inflow to Upernavik Isstrøm since 1925 CE and its relation to Glacier Retreat
Climate of the Past, 2019Co-Authors: Flor Vermassen, Nanna Andreasen, David Johannes Wangner, Nicolas Thibault, Marit-solveig Seidenkrantz, Rebecca Jackson, Sabine Schmidt, Kurt H. Kjær, Camilla S. AndresenAbstract:Abstract. The mass loss from the Greenland Ice Sheet has increased over the past 2 decades. Marine-terminating Glaciers contribute significantly to this mass loss due to increased melting and ice discharge. Periods of rapid Retreat of these tidewater Glaciers have been linked to the concurrent inflow of warm Atlantic-sourced waters. However, little is known about the variability of these Atlantic-derived waters within the fjords, due to a lack of multi-annual in situ measurements. Thus, to better understand the potential role of ocean warming on Glacier Retreat, reconstructions that characterize the variability of Atlantic water inflow to the fjords are required. Here, we investigate foraminiferal assemblages in a sediment core from Upernavik Fjord, West Greenland, in which the major ice stream Upernavik Isstrom terminates. We conclude that the foraminiferal assemblage is predominantly controlled by changes in bottom water composition and provide a reconstruction of Atlantic water inflow to Upernavik Fjord, spanning the period 1925–2012. This reconstruction reveals peak Atlantic water influx during the 1930s and again after 2000, a pattern that is comparable to the Atlantic Multidecadal Oscillation (AMO). The comparison of these results to historical observations of front positions of Upernavik Isstrom reveals that inflow of warm Atlantic-derived waters likely contributed to high Retreat rates in the 1930s and after 2000. However, moderate Retreat rates of Upernavik Isstrom also prevailed in the 1960s and 1970s, showing that Glacier Retreat continued despite a reduced Atlantic water inflow, albeit at a lower rate. Considering the link between bottom water variability and the AMO in Upernavik Fjord, and the fact that a persistent negative phase of the AMO is expected for the next decade, Atlantic water inflow into the fjord may decrease in the coming decade, potentially minimizing or stabilizing the Retreat of Upernavik Isstrom during this time interval.
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A reconstruction of warm water inflow to Upernavik Isstrøm since AD 1925 and its relation to Glacier Retreat
Climate of the Past, 2019Co-Authors: Flor Vermassen, Nanna Andreasen, David Johannes Wangner, Nicolas Thibault, Marit-solveig Seidenkrantz, Rebecca Jackson, Sabine Schmidt, Kurt Kjær, Camilla AndresenAbstract:The mass loss from the Greenland Ice Sheet has increased over the past 2 decades. Marine-terminating Glaciers contribute significantly to this mass loss due to increased melting and ice discharge. Periods of rapid Retreat of these tidewater Glaciers have been linked to the concurrent inflow of warm Atlantic-sourced waters. However, little is known about the variability of these Atlantic-derived waters within the fjords, due to a lack of multi-annual in situ measurements. Thus, to better understand the potential role of ocean warming on Glacier Retreat, reconstructions that characterize the variability of Atlantic water inflow to the fjords are required. Here, we investigate foraminiferal assemblages in a sediment core from Upernavik Fjord, West Greenland, in which the major ice stream Upernavik Isstrøm terminates. We conclude that the foraminiferal assemblage is predominantly controlled by changes in bottom water composition and provide a reconstruction of Atlantic water inflow to Upernavik Fjord, spanning the period 1925–2012. This reconstruction reveals peak Atlantic water influx during the 1930s and again after 2000, a pattern that is comparable to the Atlantic Multidecadal Oscillation (AMO). The comparison of these results to historical observations of front positions of Upernavik Isstrøm reveals that inflow of warm Atlantic-derived waters likely contributed to high Retreat rates in the 1930s and after 2000. However, moderate Retreat rates of Upernavik Isstrøm also prevailed in the 1960s and 1970s, showing that Glacier Retreat continued despite a reduced Atlantic water inflow, albeit at a lower rate. Considering the link between bottom water variability and the AMO in Upernavik Fjord, and the fact that a persistent negative phase of the AMO is expected for the next decade, Atlantic water inflow into the fjord may decrease in the coming decade, potentially minimizing or stabilizing the Retreat of Upernavik Isstrøm during this time interval.climate change