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Acoustic Mapping of Thermohaline Staircases in the Arctic Ocean.

https://arctichealth.org/en/permalink/ahliterature286972
Source
Sci Rep. 2017 Nov 09;7(1):15192
Publication Type
Article
Date
Nov-09-2017
Author
Christian Stranne
Larry Mayer
Thomas C Weber
Barry R Ruddick
Martin Jakobsson
Kevin Jerram
Elizabeth Weidner
Johan Nilsson
Katarina Gårdfeldt
Source
Sci Rep. 2017 Nov 09;7(1):15192
Date
Nov-09-2017
Language
English
Publication Type
Article
Abstract
Although there is enough heat contained in inflowing warm Atlantic Ocean water to melt all Arctic sea ice within a few years, a cold halocline limits upward heat transport from the Atlantic water. The amount of heat that penetrates the halocline to reach the sea ice is not well known, but vertical heat transport through the halocline layer can significantly increase in the presence of double diffusive convection. Such convection can occur when salinity and temperature gradients share the same sign, often resulting in the formation of thermohaline staircases. Staircase structures in the Arctic Ocean have been previously identified and the associated double diffusive convection has been suggested to influence the Arctic Ocean in general and the fate of the Arctic sea ice cover in particular. A central challenge to understanding the role of double diffusive convection in vertical heat transport is one of observation. Here, we use broadband echo sounders to characterize Arctic thermohaline staircases at their full vertical and horizontal resolution over large spatial areas (100?s of kms). In doing so, we offer new insight into the mechanism of thermohaline staircase evolution and scale, and hence fluxes, with implications for understanding ocean mixing processes and ocean-sea ice interactions.
PubMed ID
29123176 View in PubMed
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Evidence for an ice shelf covering the central Arctic Ocean during the penultimate glaciation.

https://arctichealth.org/en/permalink/ahliterature269367
Source
Nat Commun. 2016;7:10365
Publication Type
Article
Date
2016
Author
Martin Jakobsson
Johan Nilsson
Leif Anderson
Jan Backman
Göran Björk
Thomas M Cronin
Nina Kirchner
Andrey Koshurnikov
Larry Mayer
Riko Noormets
Matthew O'Regan
Christian Stranne
Roman Ananiev
Natalia Barrientos Macho
Denis Cherniykh
Helen Coxall
Björn Eriksson
Tom Flodén
Laura Gemery
Örjan Gustafsson
Kevin Jerram
Carina Johansson
Alexey Khortov
Rezwan Mohammad
Igor Semiletov
Source
Nat Commun. 2016;7:10365
Date
2016
Language
English
Publication Type
Article
Abstract
The hypothesis of a km-thick ice shelf covering the entire Arctic Ocean during peak glacial conditions was proposed nearly half a century ago. Floating ice shelves preserve few direct traces after their disappearance, making reconstructions difficult. Seafloor imprints of ice shelves should, however, exist where ice grounded along their flow paths. Here we present new evidence of ice-shelf groundings on bathymetric highs in the central Arctic Ocean, resurrecting the concept of an ice shelf extending over the entire central Arctic Ocean during at least one previous ice age. New and previously mapped glacial landforms together reveal flow of a spatially coherent, in some regions >1-km thick, central Arctic Ocean ice shelf dated to marine isotope stage 6 (~140?ka). Bathymetric highs were likely critical in the ice-shelf development by acting as pinning points where stabilizing ice rises formed, thereby providing sufficient back stress to allow ice shelf thickening.
PubMed ID
26778247 View in PubMed
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The International Bathymetric Chart of the Arctic Ocean Version 4.0.

https://arctichealth.org/en/permalink/ahliterature305328
Source
Sci Data. 2020 07 09; 7(1):176
Publication Type
Journal Article
Date
07-09-2020
Author
Martin Jakobsson
Larry A Mayer
Caroline Bringensparr
Carlos F Castro
Rezwan Mohammad
Paul Johnson
Tomer Ketter
Daniela Accettella
David Amblas
Lu An
Jan Erik Arndt
Miquel Canals
José Luis Casamor
Nolwenn Chauché
Bernard Coakley
Seth Danielson
Maurizio Demarte
Mary-Lynn Dickson
Boris Dorschel
Julian A Dowdeswell
Simon Dreutter
Alice C Fremand
Dana Gallant
John K Hall
Laura Hehemann
Hanne Hodnesdal
Jongkuk Hong
Roberta Ivaldi
Emily Kane
Ingo Klaucke
Diana W Krawczyk
Yngve Kristoffersen
Boele R Kuipers
Romain Millan
Giuseppe Masetti
Mathieu Morlighem
Riko Noormets
Megan M Prescott
Michele Rebesco
Eric Rignot
Igor Semiletov
Alex J Tate
Paola Travaglini
Isabella Velicogna
Pauline Weatherall
Wilhelm Weinrebe
Joshua K Willis
Michael Wood
Yulia Zarayskaya
Tao Zhang
Mark Zimmermann
Karl B Zinglersen
Author Affiliation
Department of Geological Sciences, Stockholm University, Stockholm, Sweden. martin.jakobsson@geo.su.se.
Source
Sci Data. 2020 07 09; 7(1):176
Date
07-09-2020
Language
English
Publication Type
Journal Article
Abstract
Bathymetry (seafloor depth), is a critical parameter providing the geospatial context for a multitude of marine scientific studies. Since 1997, the International Bathymetric Chart of the Arctic Ocean (IBCAO) has been the authoritative source of bathymetry for the Arctic Ocean. IBCAO has merged its efforts with the Nippon Foundation-GEBCO-Seabed 2030 Project, with the goal of mapping all of the oceans by 2030. Here we present the latest version (IBCAO Ver. 4.0), with more than twice the resolution (200 × 200?m versus 500 × 500?m) and with individual depth soundings constraining three times more area of the Arctic Ocean (~19.8% versus 6.7%), than the previous IBCAO Ver. 3.0 released in 2012. Modern multibeam bathymetry comprises ~14.3% in Ver. 4.0 compared to ~5.4% in Ver. 3.0. Thus, the new IBCAO Ver. 4.0 has substantially more seafloor morphological information that offers new insights into a range of submarine features and processes; for example, the improved portrayal of Greenland fjords better serves predictive modelling of the fate of the Greenland Ice Sheet.
PubMed ID
32647176 View in PubMed
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Remobilization of dormant carbon from Siberian-Arctic permafrost during three past warming events.

https://arctichealth.org/en/permalink/ahliterature304436
Source
Sci Adv. 2020 Oct; 6(42):
Publication Type
Journal Article
Date
Oct-2020
Author
Jannik Martens
Birgit Wild
Francesco Muschitiello
Matt O'Regan
Martin Jakobsson
Igor Semiletov
Oleg V Dudarev
Örjan Gustafsson
Author Affiliation
Department of Environmental Science, Stockholm University, 11418 Stockholm, Sweden. orjan.gustafsson@aces.su.se jannik.martens@aces.su.se.
Source
Sci Adv. 2020 Oct; 6(42):
Date
Oct-2020
Language
English
Publication Type
Journal Article
Abstract
Carbon cycle models suggest that past warming events in the Arctic may have caused large-scale permafrost thaw and carbon remobilization, thus affecting atmospheric CO2 levels. However, observational records are sparse, preventing spatially extensive and time-continuous reconstructions of permafrost carbon release during the late Pleistocene and early Holocene. Using carbon isotopes and biomarkers, we demonstrate that the three most recent warming events recorded in Greenland ice cores-(i) Dansgaard-Oeschger event 3 (~28 ka B.P.), (ii) Bølling-Allerød (14.7 to 12.9 ka B.P.), and (iii) early Holocene (~11.7 ka B.P.)-caused massive remobilization and carbon degradation from permafrost across northeast Siberia. This amplified permafrost carbon release by one order of magnitude, particularly during the last deglaciation when global sea-level rise caused rapid flooding of the land area thereafter constituting the vast East Siberian Arctic Shelf. Demonstration of past warming-induced release of permafrost carbon provides a benchmark for the sensitivity of these large carbon pools to changing climate.
PubMed ID
33067229 View in PubMed
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Remobilization of Old Permafrost Carbon to Chukchi Sea Sediments During the End of the Last Deglaciation.

https://arctichealth.org/en/permalink/ahliterature299553
Source
Global Biogeochem Cycles. 2019 Jan; 33(1):2-14
Publication Type
Journal Article
Date
Jan-2019
Author
Jannik Martens
Birgit Wild
Christof Pearce
Tommaso Tesi
August Andersson
Lisa Bröder
Matt O'Regan
Martin Jakobsson
Martin Sköld
Laura Gemery
Thomas M Cronin
Igor Semiletov
Oleg V Dudarev
Örjan Gustafsson
Author Affiliation
Department of Environmental Science and Analytical Chemistry (ACES) Stockholm University Stockholm Sweden.
Source
Global Biogeochem Cycles. 2019 Jan; 33(1):2-14
Date
Jan-2019
Language
English
Publication Type
Journal Article
Abstract
Climate warming is expected to destabilize permafrost carbon (PF-C) by thaw-erosion and deepening of the seasonally thawed active layer and thereby promote PF-C mineralization to CO2 and CH4. A similar PF-C remobilization might have contributed to the increase in atmospheric CO2 during deglacial warming after the last glacial maximum. Using carbon isotopes and terrestrial biomarkers (?14C, d13C, and lignin phenols), this study quantifies deposition of terrestrial carbon originating from permafrost in sediments from the Chukchi Sea (core SWERUS-L2-4-PC1). The sediment core reconstructs remobilization of permafrost carbon during the late Allerød warm period starting at 13,000 cal years before present (BP), the Younger Dryas, and the early Holocene warming until 11,000 cal years BP and compares this period with the late Holocene, from 3,650 years BP until present. Dual-carbon-isotope-based source apportionment demonstrates that Ice Complex Deposit-ice- and carbon-rich permafrost from the late Pleistocene (also referred to as Yedoma)-was the dominant source of organic carbon (66 ± 8%; mean ± standard deviation) to sediments during the end of the deglaciation, with fluxes more than twice as high (8.0 ± 4.6 g·m-2·year-1) as in the late Holocene (3.1 ± 1.0 g·m-2·year-1). These results are consistent with late deglacial PF-C remobilization observed in a Laptev Sea record, yet in contrast with PF-C sources, which at that location were dominated by active layer material from the Lena River watershed. Release of dormant PF-C from erosion of coastal permafrost during the end of the last deglaciation indicates vulnerability of Ice Complex Deposit in response to future warming and sea level changes.
PubMed ID
31007381 View in PubMed
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