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Is Ice-Rafted Sediment in a North Pole Marine Record Evidence for Perennial Sea-ice Cover?Ice-rafted sediments of Eurasian and North American origin are found consistently in the upper part (13 Ma BP to present) of the Arctic Coring Expedition (ACEX) ocean core from the Lomonosov Ridge, near the North Pole (approximately 88 degrees N). Based on modern sea-ice drift trajectories and speeds, this has been taken as evidence of the presence of a perennial sea-ice cover in the Arctic Ocean from the middle Miocene onwards. However, other high latitude land and marine records indicate a long-term trend towards cooling broken by periods of extensive warming suggestive of a seasonally ice-free Arctic between the Miocene and the present. We use a coupled sea-ice slab-ocean model including sediment transport tracers to map the spatial distribution of ice-rafted deposits in the Arctic Ocean. We use 6 hourly wind forcing and surface heat fluxes for two different climates: one with a perennial sea-ice cover similar to that of the present day and one with seasonally ice-free conditions, similar to that simulated in future projections. Model results confirm that in the present-day climate, sea ice takes more than 1 year to transport sediment from all its peripheral seas to the North Pole. However, in a warmer climate, sea-ice speeds are significantly faster (for the same wind forcing) and can deposit sediments of Laptev, East Siberian and perhaps also Beaufort Sea origin at the North Pole. This is primarily because of the fact that sea-ice interactions are much weaker with a thinner ice cover and there is less resistance to drift. We conclude that the presence of ice-rafted sediment of Eurasian and North American origin at the North Pole does not imply a perennial sea-ice cover in the Arctic Ocean, reconciling the ACEX ocean core data with other land and marine records.
Document ID
20150021896
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Tremblay, L.B.
(McGill Univ. Montreal, Quebec, Canada)
Schmidt, G.A.
(NASA Goddard Inst. for Space Studies New York, NY United States)
Pfirman, S.
(Barnard Coll. New York, NY, United States)
Newton, R.
(Lamont-Doherty Earth Observatory Palisades, NY, United States)
DeRepentigny, P.
(McGill Univ. Montreal, Quebec, Canada)
Date Acquired
November 25, 2015
Publication Date
September 7, 2015
Publication Information
Publication: Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
Publisher: The Royal Society
Volume: 373
Issue: 2052
Subject Category
Meteorology And Climatology
Oceanography
Report/Patent Number
GSFC-E-DAA-TN27542
Funding Number(s)
WBS: WBS 509496.02.08.04.24
Distribution Limits
Public
Copyright
Other
Keywords
Palaeoclimate
Arctic
Sea ice

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