Is ice-rafted sediment in a North Pole marine record evidence for perennial sea-ice cover?

Tremblay, Bruno; Schmidt, Gavin A.; Pfirman, Stephanie; Newton, R.; DeRepentigny, Patricia

doi:10.1098/rsta.2014.0168

Cited by 15 publications

(16 citation statements)

References 54 publications

(80 reference statements)

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“…Micronutrients such as iron originating from particulate matter inside sea ice are possible triggers of such blooms (Dieckmann et al, 1991;Kanna et al, 2014;Sedwick & DiTullio, 1997). Sediment transported by sea ice as well as icebergs, referred to as ice rafted debris, has deposited on the seafloor over millions of years (e.g., Polyak et al, 2010;Tremblay et al, 2015). Such ice-rafted debris can serve as a useful proxy for paleo-oceanographic and paleo-climate reconstructions.…”

Section: Introductionmentioning

confidence: 99%

Favorable Conditions for Suspension Freezing in an Arctic Coastal Polynya

et al. 2019

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Arctic sea ice incorporates and transports sediment, releasing it back into the water column during the melting season. This process constitutes an important aspect of marine sediment transport and biogeochemical cycling. Sediment incorporation into sea ice is considered to occur mainly through underwater interaction between frazil ice and resuspended sediment, referred to as suspension freezing. However, harsh environmental conditions have greatly limited field observations of this phenomenon. Analysis of mooring data from a coastal polynya in the northeastern Chukchi Sea, in conjunction with coastal ice radar and meteorological data, indicates that suspension freezing is a key mechanism for sediment entrainment into sea ice. During polynya episodes, acoustic backscatter data obtained by an Acoustic Doppler Current Profiler showed the presence of frazil ice from the surface down to 20-to 25-m depth, coinciding with in situ and potential supercooling. Underwater frazil ice persisted over 1 week under windy, turbulent water column conditions. A combination of the turbidity and Acoustic Doppler Current Profiler backscatter data revealed upward sediment dispersion associated with strong currents during the polynya episodes. The fact that frazil ice and resuspended sediment were detected at the same depth and time strongly suggests the interaction between ice crystals and sediment particles, that is, suspension freezing.Plain Language Summary Sea ice incorporates, transports, and releases particulate matter.These processes constitute an important aspect of the biology, biogeochemical cycling, and pollutant transport in polar oceans. Seafloor sediments serve as the most important source of such particulate matter; however, the process of sediment incorporation into sea ice remains poorly explored. We conducted a year-long study of sediment resuspension and entrainment processes, using underwater sensors deployed in the Chukchi Sea. During winter, wind-driven offshore transport of sea ice created area of open water and newly grown thin ice that persisted for several days, so-called coastal polynya or flaw lead system. Our sensors recorded small ice crystals, so-called frazil ice, that formed in the water column when water temperatures were below freezing point (supercooling). During some of these episodes, sediment was resuspended from the seafloor and dispersed upward by the strong currents, bringing it into water depths at which frazil ice was encountered. Such conditions provide for opportunities that allow frazil ice crystals or aggregates to capture resuspended sediment, a process referred to as suspension freezing. Based on this study, we propose that suspension freezing commonly occurs in shallow Arctic polynyas, serving as a key process of sediment incorporation into sea ice.

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Section: Introductionmentioning

confidence: 99%

Favorable Conditions for Suspension Freezing in an Arctic Coastal Polynya

et al. 2019

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“…Thus, if present, phases of perennial sea ice should have been more the exception in the middle Eocene, whereas seasonal sea ice should have been the rule. Based on the simulation of icedrift pattern and velocities under permanent and seasonal ice conditions, Trembley et al [143] challenged Darby's approach and also support a seasonal Arctic Ocean sea ice cover.…”

Section: Prominent Paleogene Events Of Anoxia: Petm Event Elmo Eventmentioning

confidence: 99%

Exploring the long-term Cenozoic Arctic Ocean climate history: a challenge within the International Ocean Discovery Program (IODP)

Stein

Jokat

Niessen

et al. 2015

Arktos

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“…Spreen et al [2011] have shown that the sea-ice acceleration is partially, but not mainly, due to increased wind stress. Rather, the main effect must be an increased responsiveness of the ice pack to winds and ocean currents as a result of lower resistance as the ice thins and the ice area diminishes [Tremblay et al, 2015].…”

Section: Transport Between Eezsmentioning

confidence: 99%

“…This occurs because most contaminants are particle reactive and even during summer ice melt are retained on the pitted, cryoconite-riddled surface of the floes . Also, for multi-year ice, over time, as ice melts from the surface and grows from the underside, contaminants migrate toward the floe surface Tremblay et al, 2015]. Once released, contaminants will segregate based on their behavior in seawater.…”

Section: Introductionmentioning

confidence: 99%

“…Transport of biological communities, dust, and marine sediments may help to seed blooms at the retreating summer ice edge [e.g., Meibing et al, 2007]. Ice-rafted sediments deposited over the central Arctic basin are read from benthic cores to document periods during the last several millions years when the Arctic was ice free or covered [e.g., Bischof and Darby, 1997;Tremblay et al, 2015].…”

Section: Introductionmentioning

confidence: 99%

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Increasing transnational sea‐ice exchange in a changing Arctic Ocean

et al. 2017

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The changing Arctic sea-ice cover is likely to impact the trans-border exchange of sea ice between the exclusive economic zones (EEZs) of the Arctic nations, affecting the risk of ice-rafted contamination. We apply the Lagrangian Ice Tracking System (LITS) to identify sea-ice formation events and track sea ice to its melt locations. Most ice (52%) melts within 100 km of where it is formed; ca. 21% escapes from its EEZ. Thus, most contaminants will be released within an ice parcel's originating EEZ, while material carried by over 1 00,000 km 2 of ice-an area larger than France and Germany combined-will be released to other nations' waters. Between the periods 1988-1999 and 2000-2014, sea-ice formation increased by ∼17% (roughly 6 million km 2 vs. 5 million km 2 annually). Melting peaks earlier; freeze-up begins later; and the central Arctic Ocean is more prominent in both formation and melt in the later period. The total area of ice transported between EEZs increased, while transit times decreased: for example, Russian ice reached melt locations in other nations' EEZs an average of 46% faster while North American ice reached destinations in Eurasian waters an average of 37% faster. Increased trans-border exchange is mainly a result of increased speed (∼14% per decade), allowing first-year ice to escape the summer melt front, even as the front extends further north. Increased trans-border exchange over shorter times is bringing the EEZs of the Arctic nations closer together, which should be taken into account in policy development-including establishment of marine-protected areas. Plain Language SummaryWe use data from satellite images to identify the formation, drift tracks, and melt locations of sea ice in the Arctic. Most ice melts locally: only about 21% is exported from the exclusive economic zone (EEZ) in which it is formed. That export is nonetheless about 1,000,000 km 2 each year. As the ice cover has thinned and the summer sea ice has retreated in a warming Arctic, formation and melt locations have moved further north, ice drifts have accelerated, and the area of ice formation and melt has increased. We looked at ice formation and transport between the EEZs of the Arctic nations, and broke the record into two periods : 1988-1999 and 2000-2014. As the Arctic warms, more ice is transported between EEZs and it is arriving at the receiving EEZ faster, than in the past. Between the two study periods: Sea ice velocity increased by about 14%/decade; Russian ice reached melt locations in other nations' EEZs 46% faster; and North American ice reached Eurasian destinations 37% faster. Exchanges of ice have increased as a result. For example, export of ice from Russia to Norway increased by 11% and export from Alaska to Russia by 16%.

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Is ice-rafted sediment in a North Pole marine record evidence for perennial sea-ice cover?

Abstract: One contribution of 6 to a discussion meeting issue 'Arctic sea ice reduction: the evidence, models and impacts (Part 2)' .

Cited by 15 publications

References 54 publications

Favorable Conditions for Suspension Freezing in an Arctic Coastal Polynya

Favorable Conditions for Suspension Freezing in an Arctic Coastal Polynya

Exploring the long-term Cenozoic Arctic Ocean climate history: a challenge within the International Ocean Discovery Program (IODP)

Increasing transnational sea‐ice exchange in a changing Arctic Ocean

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