Impact of tidewater glacier retreat on the fjord system: Modeling present and future circulation in Kongsfjorden, Svalbard

Torsvik, Tomas; Albretsen, Jon; Sundfjord, Arild; Kohler, Jack; Sandvik, Anne Dagrun; Skarðhamar, Jofrid; Lindbäck, Katrin; Everett, Alistair

doi:10.1016/j.ecss.2019.02.005

Cited by 55 publications

(89 citation statements)

References 35 publications

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“…There is no sill at the fjord entrance and thus warm Atlantic water can be found throughout the fjord in summer (Hop et al, 2002). The major marine-terminating glaciers at the fjord head (Kongsvegen and Kronebreen) have been retreating since before monitoring began (Liestøl, 1988;Svendsen et al, 2002) and are anticipated to transition to land-terminating systems in the coming decades (Torsvik et al, 2019). Research within the fjord is logged in the RIS (Research in Svalbard; https://researchinsvalbard.no) online system.…”

Section: Kongsfjorden (W Svalbard) 79° N 012° Ementioning

confidence: 99%

Review Article: How does glacier discharge affect marine biogeochemistry and primary production in the Arctic?

Hopwood¹,

Carroll²,

Dunse³

et al. 2019

Preprint

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Abstract. Freshwater discharge from glaciers is increasing across the Artic in response to anthropogenic climate change, which raises questions about the potential downstream effects in the marine environment. Whilst a combination of long-term monitoring programmes and intensive Arctic field campaigns have improved our knowledge of glacier-ocean interactions in recent years, especially with respect to fjord/ocean circulation in the marine environment, there are extensive knowledge gaps concerning how glaciers affect marine biogeochemistry and productivity. Following two cross-cutting disciplinary International Arctic Science Committee (IASC) workshops addressing ‘The importance of glaciers for the marine ecosystem’, here we review the state of the art concerning how freshwater discharge affects the marine environment with a specific focus on marine biogeochemistry and biological productivity. Using a series of Arctic case studies (Nuup Kangerlua/Godthåbsfjord, Kongsfjorden, Bowdoin Fjord, Young Sound, and Sermilik Fjord), the interconnected effects of freshwater discharge on fjord-shelf exchange, nutrient availability, the carbonate system, and the microbial foodweb are investigated. Key findings are that whether the effect of glacier discharge on marine primary production is positive, or negative is highly dependent on a combination of factors. These include glacier type (marine- or land-terminating) and the limiting resource for phytoplankton growth in a specific spatiotemporal region (light, macronutrients or micronutrients). Glacier fjords therefore often exhibit distinct discharge-productivity relationships and multiple case-studies must be considered in order to understand the net effects of glacier discharge on Arctic marine ecosystems.

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Section: Kongsfjorden (W Svalbard) 79° N 012° Ementioning

confidence: 99%

Review Article: How does glacier discharge affect marine biogeochemistry and primary production in the Arctic?

Hopwood¹,

Carroll²,

Dunse³

et al. 2019

Preprint

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“…Mass loss is dominated by frontal ablation (Nuth et al, 2012;Luckman et al, 2015), making it an ideal candidate to further understand the processes of calving and frontal ablation. The glacier is currently experiencing an accelerated, rapid retreat, which amounts to more than 1 km since 2012 (Schellenberger et al, 2015;Köhler et al, 2016;Vallot et al, 2018;Deschamps-Berger et al, 2019) with considerable future implications for the fjord ecosystem (Torsvik et al, 2019). At the end of August 2016 a multidisciplinary field campaign was carried out to measure the calving front of Kronebreen continuously over a 2-week period with simultaneous acquisitions from time-lapse cameras, a lidar scanner, terrestrial radar interferometry, passive seismic, and hydroacoustic arrays (Köhler et al, 2019).…”

Section: Study Site and Calving Recordsmentioning

confidence: 99%

Contribution of calving to frontal ablation quantified from seismic and hydroacoustic observations calibrated with lidar volume measurements

Köhler

Pętlicki²,

Lefeuvre

et al. 2019

The Cryosphere

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Abstract. Frontal ablation contributes significantly to the mass balance of tidewater glaciers in Svalbard and can be recovered with high temporal resolution using continuous seismic records. Determination of the relative contribution of dynamic ice loss through calving to frontal ablation requires precise estimates of calving volumes at the same temporal resolution. We combine seismic and hydroacoustic observations close to the calving front of Kronebreen, a marine-terminating glacier in Svalbard, with repeat lidar scanning of the glacier front. Simultaneous time-lapse photography is used to assign volumes measured from lidar scans to seismically detected calving events. Empirical models derived from signal properties such as integrated amplitude are able to replicate volumes of individual calving events and cumulative subaerial ice loss over different lidar scan intervals from seismic and hydroacoustic data alone. This enables quantification of the contribution of calving to frontal ablation, which we estimate for Kronebreen to be about 18 %–30 %, slightly below the subaerially exposed area of the glacier front. We further develop a model calibrated for the permanent seismic Kings Bay station (KBS) at about 15 km distance from the glacier front, where 15 %–60 % of calving events can be detected under variable noise conditions due to reduced signal amplitudes at distance. Between 2007 and 2017, we find a 5 %–30 % contribution of calving ice blocks to frontal ablation, which emphasizes the importance of underwater melting (roughly 4–9 m d−1). This study shows the feasibility to seismically monitor not only frontal ablation rates but also the dynamic ice loss contribution continuously and at high temporal resolution.

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“…These glaciers modify the hydrography and biogeochemistry of fjords through meltwater runoff (Straneo et al, 2011;Bartholomaus et al, 2013;Meire et al, 2016b;Kanna et al, 2018;Cape et al, 2019) and offer important foraging areas for seabirds, seals, and white whales (Lydersen et al, 2014;Urbanski et al, 2017;Everett et al, 2018). The continuing retreat of tidewater glaciers, which will eventually terminate on land, is expected to have negative consequences for fjord circulation, productivity, and commercial fisheries (Meire et al, 2017;Torsvik et al, 2019), emphasising the need to improve our understanding of biological-physical coupling in partly or fully glaciated fjords.…”

Section: Introductionmentioning

confidence: 99%

Tidewater Glaciers and Bedrock Characteristics Control the Phytoplankton Growth Environment in a Fjord in the Arctic

et al. 2019

Self Cite

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Meltwater discharge from tidewater glaciers impacts the adjacent marine environment. Due to the global warming, tidewater glaciers are retreating and will eventually terminate on land. Yet, the mechanisms through which meltwater runoff and subglacial discharge from tidewater glaciers influence marine primary production remain poorly understood, as data in close proximity to glacier fronts are scarce. Here, we show that subglacial meltwater discharge and bedrock characteristics of the catchments control the phytoplankton growth environment inside the fjord, based on data collected in close proximity to tidewater glacier fronts in Kongsfjorden, Svalbard from 26 to 31 July 2017. In the southern part of the inner fjord, glacial meltwater from subglacial discharge was rich in fine sediments derived from erosion of Devonian Old Red Sandstone and carbonate rock deposits, limiting light availability for phytoplankton (0.6 mg m −3 Chl a on average, range 0.2-1.9 mg m −3). In contrast, coarser sediments derived from gneiss and granite bedrock and lower subglacial discharge rates were associated with more favourable light conditions facilitating a local phytoplankton bloom in the northern part of the inner fjord with mean Chl a concentration of 2.8 mg m −3 (range 1.3-7.4 mg m −3). In the northern part, glacier meltwater was a direct source of silicic acid through weathering of the silica-rich gneiss and granite bedrock. Upwelling of the subglacial freshwater discharge plume at the Kronebreen glacier front in the southern part entrained large volumes of ambient, nutrient-rich bottom waters which led to elevated surface concentrations of ammonium, nitrate, and partly silicic acid. Total dissolved inorganic nitrogen transported to the surface with the upwelling of the subglacial discharge plume has a significant potential to enhance summer primary production in Kongsfjorden, with ammonium released from the seafloor being of particular importance. The transition from tidewater to land-terminating glaciers may, thus, reduce the input of nutrients to the surface layer with negative consequences for summer productivity.

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Impact of tidewater glacier retreat on the fjord system: Modeling present and future circulation in Kongsfjorden, Svalbard

Cited by 55 publications

References 35 publications

Review Article: How does glacier discharge affect marine biogeochemistry and primary production in the Arctic?

Review Article: How does glacier discharge affect marine biogeochemistry and primary production in the Arctic?

Contribution of calving to frontal ablation quantified from seismic and hydroacoustic observations calibrated with lidar volume measurements

Tidewater Glaciers and Bedrock Characteristics Control the Phytoplankton Growth Environment in a Fjord in the Arctic

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