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

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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Local solutions to manage the effects of global climate change on a marine ecosystem: a process guide for marine resource managers

ICES Journal of Marine Science ◽

10.1093/icesjms/fsp133 ◽

2009 ◽

Vol 66 (7) ◽

pp. 1640-1646 ◽

Cited By ~ 5

Author(s):

Kelley D. Higgason ◽

Maria Brown

Keyword(s):

Climate Change ◽

Marine Environment ◽

Ocean Circulation ◽

Global Climate Change ◽

Global Climate ◽

Marine Ecosystem ◽

Community Outreach ◽

Marine Resource ◽

Resource Managers ◽

Local Solutions

Abstract Higgason, K. D., and Brown, M. 2009. Local solutions to manage the effects of global climate change on a marine ecosystem: a process guide for marine resource managers. – ICES Journal of Marine Science, 66: 1640–1646. The marine environment plays an important role in controlling the amount of CO2 that remains within the earth’s atmosphere, but it has not received as much attention as the terrestrial environment regarding climate-change effects, mitigation programmes, and action plans. Potential physical effects of climate change within the marine environment, including ocean acidification, changes in winds that drive upwelling and ocean circulation patterns, increasing global sea surface temperatures, and sea level rise, can result in dramatic changes within marine and coastal ecosystems. Often, marine resource managers feel overwhelmed by the magnitude of this issue and are therefore uncertain how to begin to take action. It may seem that they do not have the time, funding, or staff to take on a challenge as large as climate change, and fail to act as a result. Using NOAA’s Gulf of the Farallones National Marine Sanctuary as a case study, this paper outlines the need to act now and presents an easy-to-use process guide, providing managers options to incorporate effectively the influences of climate change into management strategies, as well as mitigate these influences through community outreach and a reduction in workplace emissions.

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Review of “How does glacier discharge affect marine biogeochemistry and primary production in the Arctic” by Hopwood et al.

10.5194/tc-2019-136-rc1 ◽

2019 ◽

Author(s):

Jon Hawkings

Keyword(s):

Primary Production ◽

The Arctic ◽

Marine Biogeochemistry

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Southwest Pacific Paleoceanography During the Late Holocene: 3000 years of ocean circulation and marine biogeochemistry reconstructed from New Zealand deep-sea black corals

10.26686/wgtn.14043953 ◽

2021 ◽

Author(s):

Nicholas Hitt

Keyword(s):

Primary Production ◽

Ocean Circulation ◽

Late Holocene ◽

Phytoplankton Community ◽

Southern Oscillation ◽

Southwest Pacific ◽

Black Coral ◽

Black Corals ◽

Marine Biogeochemistry ◽

Gyre Circulation

The global climate results from interactions between the ocean and atmosphere. Ocean gyres are perhaps one of the most significant interactions; they regulate temperature, salinity and nutrient flow across the ocean basins. Gyres transport warm, tropical waters to higher latitudes and cold waters to lower latitudes and act as the dominant heat-transport mechanism in the Earth’s climate system. They also influence spatial patterns in marine primary production by distributing nutrients between the equator and poles. However, gyre circulation in the subtropics has been strengthening, leading to marine heat waves, changing biogeochemistry and reducing primary production since the early 1900s. These changes are often interpreted as a consequence of anthropogenic climate change. However, ocean circulation and primary production can exhibit natural variations on a variety of timescales. Could these recent changes be a part of a long-term natural cycle or a product of anthropogenic change? This research aims to reconstruct South Pacific Gyre (SPG) circulation and biogeochemistry using a suite of New Zealand black corals. The primary research goal is determining if there is a precedent for the ocean changes observed over the instrumental period. Black corals are an ideal paleoceanographic archive for this work; they provide high-resolution, multi-millennial records of biogeochemistry and ocean circulation within their skeletons, derived using radiocarbon (14C) and stable isotopes (d13C and d15N). In this thesis, I show that late Holocene SPG strength has been highly variable and the relationship between circulation and biogeochemistry is timescale dependent. The black coral radiocarbon records suggest late Holocene SPG circulation has been controlled by westerly wind strength. Our records show the SPG exhibits natural variability on multi-centennial and millennial timescales that corresponds to the variability within the Southern Annular Mode (SAM) and the El Niño-Southern Oscillation (ENSO). The black coral circulation record shows that the modern gyre circulation is not without precedent over the last 3000 years. The black coral d13C and d15N records show significant variability on multi-decadal to multi-centennial timescales. Multi-centennial variability in black coral d13C and d15N appears to be driven by sea surface temperature (SST), nitrogen fixation rates and wind-driven upwelling and is possibly forced by the mean state of the Southern Oscillation Index and ocean circulation strength. A trend in black coral d13C over the last 1500 years also suggests a shift in phytoplankton community structure towards larger and faster growing phytoplankton. These records also reveal a shift in mean coral d13C and d15N between the 0-2000BP and 2000-3000BP period, the latter corresponding to a period of stronger gyre circulation inferred from the radiocarbon records. This work shows that: 1) New Zealand’s black corals are a promising archive for studying paleoceanography; they can extend instrumental ocean records and fill the gap between traditional southwest Pacific paleoceanographic proxy records (tropical corals, sediment cores); 2) SPG circulation has been highly variable over the last 3000 years; circulation is controlled by atmospheric patterns (e.g. SAM) on multi-centennial to millennial timescales; 3) Gyre circulation is only one of many forcing factors on southwest Pacific primary production and marine biogeochemistry; comparisons between the ∆R, d13C and d15N proxies show that variations in SPG biogeochemical patterns and productivity are likely driven by local dynamics such as phytoplankton community structure, SST, upwelling and gyre circulation. Finally, this research demonstrates the key role that a distributed set of deep-sea coral paleoceanographic reconstructions could play in characterizing the dynamical variability in southwest Pacific Ocean circulation, biogeochemistry and primary production. This information is critical for detecting and attributing past and future anthropogenic impacts on the southwest Pacific Ocean.

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Southwest Pacific Paleoceanography During the Late Holocene: 3000 years of ocean circulation and marine biogeochemistry reconstructed from New Zealand deep-sea black corals

10.26686/wgtn.14043953.v1 ◽

2021 ◽

Author(s):

Nicholas Hitt

Keyword(s):

Primary Production ◽

Ocean Circulation ◽

Late Holocene ◽

Phytoplankton Community ◽

Southern Oscillation ◽

Southwest Pacific ◽

Black Coral ◽

Black Corals ◽

Marine Biogeochemistry ◽

Gyre Circulation

The global climate results from interactions between the ocean and atmosphere. Ocean gyres are perhaps one of the most significant interactions; they regulate temperature, salinity and nutrient flow across the ocean basins. Gyres transport warm, tropical waters to higher latitudes and cold waters to lower latitudes and act as the dominant heat-transport mechanism in the Earth’s climate system. They also influence spatial patterns in marine primary production by distributing nutrients between the equator and poles. However, gyre circulation in the subtropics has been strengthening, leading to marine heat waves, changing biogeochemistry and reducing primary production since the early 1900s. These changes are often interpreted as a consequence of anthropogenic climate change. However, ocean circulation and primary production can exhibit natural variations on a variety of timescales. Could these recent changes be a part of a long-term natural cycle or a product of anthropogenic change? This research aims to reconstruct South Pacific Gyre (SPG) circulation and biogeochemistry using a suite of New Zealand black corals. The primary research goal is determining if there is a precedent for the ocean changes observed over the instrumental period. Black corals are an ideal paleoceanographic archive for this work; they provide high-resolution, multi-millennial records of biogeochemistry and ocean circulation within their skeletons, derived using radiocarbon (14C) and stable isotopes (d13C and d15N). In this thesis, I show that late Holocene SPG strength has been highly variable and the relationship between circulation and biogeochemistry is timescale dependent. The black coral radiocarbon records suggest late Holocene SPG circulation has been controlled by westerly wind strength. Our records show the SPG exhibits natural variability on multi-centennial and millennial timescales that corresponds to the variability within the Southern Annular Mode (SAM) and the El Niño-Southern Oscillation (ENSO). The black coral circulation record shows that the modern gyre circulation is not without precedent over the last 3000 years. The black coral d13C and d15N records show significant variability on multi-decadal to multi-centennial timescales. Multi-centennial variability in black coral d13C and d15N appears to be driven by sea surface temperature (SST), nitrogen fixation rates and wind-driven upwelling and is possibly forced by the mean state of the Southern Oscillation Index and ocean circulation strength. A trend in black coral d13C over the last 1500 years also suggests a shift in phytoplankton community structure towards larger and faster growing phytoplankton. These records also reveal a shift in mean coral d13C and d15N between the 0-2000BP and 2000-3000BP period, the latter corresponding to a period of stronger gyre circulation inferred from the radiocarbon records. This work shows that: 1) New Zealand’s black corals are a promising archive for studying paleoceanography; they can extend instrumental ocean records and fill the gap between traditional southwest Pacific paleoceanographic proxy records (tropical corals, sediment cores); 2) SPG circulation has been highly variable over the last 3000 years; circulation is controlled by atmospheric patterns (e.g. SAM) on multi-centennial to millennial timescales; 3) Gyre circulation is only one of many forcing factors on southwest Pacific primary production and marine biogeochemistry; comparisons between the ∆R, d13C and d15N proxies show that variations in SPG biogeochemical patterns and productivity are likely driven by local dynamics such as phytoplankton community structure, SST, upwelling and gyre circulation. Finally, this research demonstrates the key role that a distributed set of deep-sea coral paleoceanographic reconstructions could play in characterizing the dynamical variability in southwest Pacific Ocean circulation, biogeochemistry and primary production. This information is critical for detecting and attributing past and future anthropogenic impacts on the southwest Pacific Ocean.

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Reviewer Comments: "How does glacier discharge affect marine biogeochemistry and primary production in the Arctic?” by Mark J. Hopwood et al

10.5194/tc-2019-136-rc2 ◽

2019 ◽

Author(s):

Kiefer Forsch

Keyword(s):

Primary Production ◽

The Arctic ◽

Marine Biogeochemistry

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Advective pathways of nutrients and key ecological substances in the Arctic

10.5194/egusphere-egu21-15538 ◽

2021 ◽

Author(s):

Myriel Vredenborg ◽

Benjamin Rabe ◽

Sinhue Torres-Valdès

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

Ocean Circulation ◽

Environmental Changes ◽

Marine Ecosystem ◽

Ocean Model ◽

The Arctic ◽

Large Set ◽

Sea Ice Extent ◽

Near Surface

The Arctic Ocean is undergoing remarkable environmental changes due to global warming. The rise in the Arctic near-surface air temperature during the past decades is more than twice as high as the global average, a phenomenon known as the &#8220;Arctic Amplification&#8221;. As a consequence the Arctic summer sea ice extent has decreased by more than 40 % in recent decades, and moreover a year-round sea ice loss in extent and thickness was recorded. By opening up of large areas formerly covered by sea ice, the exchange of heat, moisture and momentum between the ocean and the atmosphere intensified. This resulted in changes in the ocean circulation and the water masses impacting the marine ecosystem. We investigate these changes by using a large set of hydrographic and biogeochemical data of the entire Arctic Ocean. To better quantify the current changes in the Arctic ecosystem we will compare our observational data analysis with high-resolution biogeochemical atmosphere-ice-ocean model simulations.

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A geodetic approach to Mapping and Parametrization of Argo Temperature and Salinity Profiles

10.5194/egusphere-egu21-2828 ◽

2021 ◽

Author(s):

Alisa Yakhontova ◽

Roelof Rietbroek ◽

Sophie Stolzenberger ◽

Nadja Jonas

Keyword(s):

Ocean Circulation ◽

Circulation Model ◽

Deep Ocean ◽

The Arctic ◽

Argo Data ◽

Mapping Procedure ◽

Covariance Functions ◽

Temporal Sampling ◽

Spatio Temporal ◽

Sampling Problems

This study addresses mapping of Argo temperature and salinity profiles onto arbitrary positions using physically advanced statistical information from model fields, and their subsequent parametrization as function of depth. Argo suffers from spatio-temporal sampling problems, and some signals are not well captured, e.g. in the deeper ocean below 2000m, around the boundary currents, in the Arctic or in the shelf/coastal regions which are not frequently visited by floats. Mapping of Argo data into sparsely sampled areas would greatly benefit from additional physical information of coherent T/S behavior in form of covariance functions. Outputs from global general ocean circulation model FESOM1.4 provide covariance information for least squares collocation and also complement the spatially undersampled Argo data in high latitudes and in deep ocean. Additionally, model covariances are used to identify areas of strong correlation with interpolation points, so that only Argo measurements inside these areas are included in the mapping procedure. Parametrization of T/S profiles is performed with b-splines where the choice of knot locations is a trade-off between accuracy and overfitting. Proposed methodology is tested in South Atlantic, but can be extended to other regions.

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Southwest Pacific Paleoceanography During the Late Holocene: 3000 years of ocean circulation and marine biogeochemistry reconstructed from New Zealand deep-sea black corals

10.26686/wgtn.14043953.v2 ◽

2021 ◽

Author(s):

Nicholas Hitt

Keyword(s):

Primary Production ◽

Ocean Circulation ◽

Late Holocene ◽

Phytoplankton Community ◽

Southern Oscillation ◽

Southwest Pacific ◽

Black Coral ◽

Black Corals ◽

Marine Biogeochemistry ◽

Gyre Circulation

The global climate results from interactions between the ocean and atmosphere. Ocean gyres are perhaps one of the most significant interactions; they regulate temperature, salinity and nutrient flow across the ocean basins. Gyres transport warm, tropical waters to higher latitudes and cold waters to lower latitudes and act as the dominant heat-transport mechanism in the Earth’s climate system. They also influence spatial patterns in marine primary production by distributing nutrients between the equator and poles. However, gyre circulation in the subtropics has been strengthening, leading to marine heat waves, changing biogeochemistry and reducing primary production since the early 1900s. These changes are often interpreted as a consequence of anthropogenic climate change. However, ocean circulation and primary production can exhibit natural variations on a variety of timescales. Could these recent changes be a part of a long-term natural cycle or a product of anthropogenic change? This research aims to reconstruct South Pacific Gyre (SPG) circulation and biogeochemistry using a suite of New Zealand black corals. The primary research goal is determining if there is a precedent for the ocean changes observed over the instrumental period. Black corals are an ideal paleoceanographic archive for this work; they provide high-resolution, multi-millennial records of biogeochemistry and ocean circulation within their skeletons, derived using radiocarbon (14C) and stable isotopes (d13C and d15N). In this thesis, I show that late Holocene SPG strength has been highly variable and the relationship between circulation and biogeochemistry is timescale dependent. The black coral radiocarbon records suggest late Holocene SPG circulation has been controlled by westerly wind strength. Our records show the SPG exhibits natural variability on multi-centennial and millennial timescales that corresponds to the variability within the Southern Annular Mode (SAM) and the El Niño-Southern Oscillation (ENSO). The black coral circulation record shows that the modern gyre circulation is not without precedent over the last 3000 years. The black coral d13C and d15N records show significant variability on multi-decadal to multi-centennial timescales. Multi-centennial variability in black coral d13C and d15N appears to be driven by sea surface temperature (SST), nitrogen fixation rates and wind-driven upwelling and is possibly forced by the mean state of the Southern Oscillation Index and ocean circulation strength. A trend in black coral d13C over the last 1500 years also suggests a shift in phytoplankton community structure towards larger and faster growing phytoplankton. These records also reveal a shift in mean coral d13C and d15N between the 0-2000BP and 2000-3000BP period, the latter corresponding to a period of stronger gyre circulation inferred from the radiocarbon records. This work shows that: 1) New Zealand’s black corals are a promising archive for studying paleoceanography; they can extend instrumental ocean records and fill the gap between traditional southwest Pacific paleoceanographic proxy records (tropical corals, sediment cores); 2) SPG circulation has been highly variable over the last 3000 years; circulation is controlled by atmospheric patterns (e.g. SAM) on multi-centennial to millennial timescales; 3) Gyre circulation is only one of many forcing factors on southwest Pacific primary production and marine biogeochemistry; comparisons between the ∆R, d13C and d15N proxies show that variations in SPG biogeochemical patterns and productivity are likely driven by local dynamics such as phytoplankton community structure, SST, upwelling and gyre circulation. Finally, this research demonstrates the key role that a distributed set of deep-sea coral paleoceanographic reconstructions could play in characterizing the dynamical variability in southwest Pacific Ocean circulation, biogeochemistry and primary production. This information is critical for detecting and attributing past and future anthropogenic impacts on the southwest Pacific Ocean.

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Description of a global marine particulate organic carbon-13 isotope data set

10.5194/essd-2021-159 ◽

2021 ◽

Author(s):

Maria-Theresia Verwega ◽

Christopher J. Somes ◽

Markus Schartau ◽

Robyn E. Tuerena ◽

Anne Lorrain ◽

...

Keyword(s):

Organic Carbon ◽

Southern Ocean ◽

Particulate Organic Carbon ◽

Marine Ecosystem ◽

The Arctic ◽

Sample Collection ◽

Temporal And Spatial Distribution ◽

Data Set ◽

Spatio Temporal ◽

The 1960S

Abstract. Marine particulate organic carbon-13 stable isotope ratios (δ13CPOC) provide insights in understanding carbon cycling through the atmosphere, ocean, and biosphere. They have been used to trace the input of anthropogenic carbon in the marine ecosystem due to the distinct isotopically light signature of anthropogenic emissions. However, δ13CPOC is also significantly altered during photosynthesis by phytoplankton, which complicates its interpretation. For such purposes, robust spatio-temporal coverage of δ13CP OC observations is essential. We collected all such available data sets, merged and homogenized them to provide the largest available marine δ13CPOC data set (Verwega et al., 2021). The data set consists of 4732 data points covering all major ocean basins beginning in the 1960s. We describe the compiled raw data, compare different observational methods, and provide key insights in the temporal and spatial distribution that is consistent with previously observed patterns. The main different sample collection methods (bottle, intake, net, trap) are generally consistent with each other when comparing within regions. An analysis of 1990s mean δ13CP OC values in an meridional section accross the Atlantic Ocean shows relatively high values (≥ −22 ‰) in the low latitudes (< 30°) trending towards lower values in the Arctic Ocean (∼ −24 ‰) and Southern Ocean (≤ −28 ‰). The temporal trend since the 1960s shows a decrease of mean δ13CPOC by more than 3 ‰ in all basins except for the Southern Ocean which shows a weaker trend but contains relatively poor multi-decadal coverage.

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