Arctic river discharge trends since 7ka BP

Wagner, A. James; Lohmann, Gerrit; Prange, Matthias

doi:10.1016/j.gloplacha.2011.07.006

Cited by 44 publications

(41 citation statements)

References 89 publications

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“…These include decreasing summer and winter sea-ice extent, increasing annual river discharge, increasing areal extent of open-water areas over the Arctic shelves and lengthening of the open-water season Serreze et al 2007;Kwok et al 2009;Wagner et al 2011;Stroeve et al 2012;Fichot et al 2013;Zhang et al 2013). These changes will likely lead to important transformations in sedimentary environments and the pathways and processes of terrigeneous particulate cycling.…”

Section: Introductionmentioning

confidence: 99%

“…Marine proxy data indicate that this event lasted ca. 150Á 250 years (e.g., Alley et al 1997;Kleiven et al 2008;Werner et al 2013) and was triggered by the massive outburst flood from the proglacial lakes Agassiz/Ojibway during the final collapse of the Laurentide Ice Sheet (e.g., Stuiver et al 1995; Barber et al 1999;Rohling & Pä like 2005).Reconstructions based on the coupled atmosphereÁ ocean global climate model ECHO-G suggest that there was a slight increase in total Arctic river discharge ('0.35%90.45%), with an increase in the Eurasian Arctic river discharge ('2.14%90.56%) but a decrease in the North American river discharge between 7 Kya and 1800 AD ( (4.6290.64%; Supplementary Table S1; Wagner et al 2011). The increasing discharge trends from the Eurasian rivers Dvina, Pechora, Ob, Yenisei and Lena are associated with a positive precipitation and evaporation relation owing to decreased summer temperatures, as well as an intensification of continental high pressure cells, cloud formation and increased precipitation (Wagner et al 2011).…”

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Variability in transport of terrigenous material on the shelves and the deep Arctic Ocean during the Holocene

Wegner

Bennett

Vernal³

et al. 2015

Polar Research

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Arctic coastal zones serve as a sensitive filter for terrigenous matter input onto the shelves via river discharge and coastal erosion. This material is further distributed across the Arctic by ocean currents and sea ice. The coastal regions are particularly vulnerable to changes related to recent climate change. We compiled a pan-Arctic review that looks into the changing Holocene sources, transport processes and sinks of terrigenous sediment in the Arctic Ocean. Existing palaeoceanographic studies demonstrate how climate warming and the disappearance of ice sheets during the early Holocene initiated eustatic sea-level rise that greatly modified the physiography of the Arctic Ocean. Sedimentation rates over the shelves and slopes were much greater during periods of rapid sea-level rise in the early and middle Holocene, as a result of the relative distance to the terrestrial sediment sources. However, estimates of suspended sediment delivery through major Arctic rivers do not indicate enhanced delivery during this time, which suggests enhanced rates of coastal erosion. The increased supply of terrigenous material to the outer shelves and deep Arctic Ocean in the early and middle Holocene might serve as analogous to forecast changes in the future Arctic.To access the supplementary material for this article, please see supplementary files under Article Tools online.Rapid changes in the environmental conditions of the Arctic have been observed over recent decades. These include decreasing summer and winter sea-ice extent, increasing annual river discharge, increasing areal extent of open-water areas over the Arctic shelves and lengthening of the open-water season Serreze et al. 2007;Kwok et al. 2009;Wagner et al. 2011;Stroeve et al. 2012;Fichot et al. 2013;Zhang et al. 2013). These changes will likely lead to important transformations in sedimentary environments and the pathways and processes of terrigeneous particulate cycling. In particular, they could play a role in sediment resuspension and coastal erosion (e.g., Atkinson 2005;Eicken et al. 2005; Carmack et al. 2006; Anisimov et al. 2007;Lantuit et al. 2012).The impact of increased export of turbid waters from rivers and coastal regions on Arctic marine ecosystems remains uncertain; it could either increase delivery of nutrients and promote productivity or suppress photosynthesis in the light-limited algal populations by scattering absorbing sunlight (Retamal et al. 2008). An adequate understanding of the pathways of terrigenous material is needed to elucidate connections between sediment and ecosystem dynamics under a changing climate. Research efforts assessing recent trends and variability of terrigenous particulate matter inputs into the Arctic Ocean have been carried out during the past decades and discussed in reviews by Rachold et al. (2004), Macdonald et al. (2010), Forbes (2011) and Goñ i et al. (2013). However, the ability to forecast the future significance of land-derived sedimentary inputs into the Arctic Ocean also needs to account for th...

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Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

Variability in transport of terrigenous material on the shelves and the deep Arctic Ocean during the Holocene

Wegner

Bennett

Vernal³

et al. 2015

Polar Research

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“…Unlike large rivers, where decadal to centennial discharge fluctuations can be constrained to a ±10% window 11,12 , coastal erosion fluxes have the potential to increase by an order of magnitude on the same timescale 13 . Such increases would result in drastic impacts on global carbon fluxes and their climate feedbacks, on nearshore food webs, and on local communities, whose survival still relies on marine biological resources.…”

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confidence: 99%

Collapsing Arctic coastlines

2017

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A holistic and transdisciplinary approach is urgently required to investigate the physical and socio-economic impacts of collapsing coastlines in the Arctic nearshore zone.A rctic permafrost coasts account for 34% of Earth's coasts 1 . Coastal erosion rates as high as 25 m yr -1 (refs 2,3) together with the large amount of organic matter frozen in permafrost 4,5 are resulting in an annual release of 14.0 Tg (10 12 grams) of particulate organic carbon into the nearshore zone 6,7 . This carbon flux is in the same order of magnitude as the yearly contribution from all Arctic rivers, or the vertical net methane (CH 4 ) emissions from terrestrial permafrost 8 . Arctic nearshore zones (shallower than 20 m water depth) represent about 20% of the shelves and 7.5% of the Arctic Ocean -a much greater proportion than for the rest of the Earth, where the nearshore zone occupies only 1.4% of the world's ocean area 9,10 . Rapid environmental changes that occur in the Arctic nearshore zone are systematically under-studied, because icebreaking research vessels avoid these shallow waters, and there is very limited shore-based research infrastructure. However, this zone is the primary recipient of increasing fluxes of carbon and nutrients from thawing permafrost. We highlight the crucial role the nearshore zone plays in Arctic biogeochemical cycling, as the fate of the released material is determined in this location. It may (i) degrade into greenhouse gases, (ii) fuel marine primary production, (iii) be buried in nearshore sediments or (iv) be transported offshore (Fig. 1).Fluxes from coastal erosion are expected to drastically increase due to the combined effect of declining summer sea-ice cover on the Arctic Ocean, longer and warmer thawing seasons, and the rising sea level allowing waves to hit the coast higher and longer during the ice-free season. Unlike large rivers, where decadal to centennial discharge fluctuations can be constrained to a ±10% window 11,12 , coastal erosion fluxes have the potential to increase by an order of magnitude on the same timescale 13 . Such increases would result in drastic impacts on global carbon fluxes and their climate feedbacks, on nearshore food webs, and on local communities, whose survival still relies on marine biological resources. Environment and societyCurrently, most Arctic research is focused on permafrost in tundra and boreal landscapes and on the potential vertical greenhouse gas fluxes resulting from gradual permafrost thaw 4 . Although emission scenarios from gradual permafrost carbon degradation are urgently needed to better constrain Earth system models, impacts of accelerating coastal erosion on nearshore ecosystems are immediate and irreversible. Arctic warming and sea level rise account for the observed coastline collapse as an abrupt form of permafrost degradation that leads to the rapid release of large amounts of previously frozen organic carbon to the nearshore zone. The fate of this permafrost carbon, however, has never been properly quantified. Eroding coasts will ...

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“…The base of core PM9482 dates back to approximately 2.8 ka (modified from [12]) present-day sea ice production was approached only after sea level reached its highstand at *5-6 ka. Although the variability of total river discharge to the Arctic Ocean in the first half of the Holocene is unknown, only minor changes were indicated between 7 ka and *1800 AD by numerical modeling [93]. However, the records from the Laptev Sea shelf (Fig.…”

Section: Late Quaternary Freshwater Variability and Events In The Arcmentioning

confidence: 99%

The role of Arctic Ocean freshwater during the past 200 ky

Spielhagen

Bauch

2015

Arktos

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As part of the hydrologic cycle, the freshwater system plays a pivotal role for the Arctic Ocean. It maintains the strong stratification in the upper waters and fosters the formation of sea ice on the circum-Arctic shelves from where the ice is being exported toward Fram Strait and into the Nordic Seas. Recent projections of climate change under the greenhouse effect predict severe changes for the hydrologic cycle in the Arctic. This manuscript reviews the current knowledge of past changes in freshwater fluxes to and from the Arctic Ocean and their possible impact on ocean circulation and climate outside the Arctic during the past 200,000 years. It becomes evident that abrupt and large-volume discharges into the Arctic Ocean during times of major climate transitions were capable of disturbing the global ocean circulation and triggering further climate change, e.g., at the onset of the Younger Dryas cold event. During sea-level rise in the Holocene, a connection between the increasing areas available for sea ice formation, the position of the ice margin in the ice export area (the Fram Strait) and the deepwater convection in the Greenland Sea is suggested. Further work is needed to investigate the effects of other catastrophic freshwater discharges from previously ice-dammed lakes in northern Eurasia during the Weichselian and Saalian glaciations. Events like the 8.2 ka and the Younger Dryas, which were associated with flooding and routing of glacial meltwaters and had a significant effect on climate, could serve as a template to better validate the impact of similar occurrences in the past. To date, the actual influence of the earlier events on ocean circulation and climate remains elusive.

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Arctic river discharge trends since 7ka BP

Cited by 44 publications

References 89 publications

Variability in transport of terrigenous material on the shelves and the deep Arctic Ocean during the Holocene

Variability in transport of terrigenous material on the shelves and the deep Arctic Ocean during the Holocene

Collapsing Arctic coastlines

The role of Arctic Ocean freshwater during the past 200 ky

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