A new calibrated deglacial drainage history for North America and
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A new calibrated deglacial drainage history for North America and evidence for an Arctic trigger for the Younger Dryas. Lev Tarasov and W. R. Peltier University of Toronto. Outline. The issue: meltwater, Bolling-Allerod (B-A) and Younger Dryas (YD) Model and data Drainage results

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Lev Tarasov and W. R. Peltier University of Toronto

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Lev tarasov and w r peltier university of toronto

A new calibrated deglacial drainage history for North America andevidence for an Arctic trigger for the Younger Dryas

Lev Tarasov and W. R. Peltier

University of Toronto


Outline

Outline

The issue: meltwater, Bolling-Allerod (B-A) and Younger Dryas (YD)

Model and data

Drainage results

Implications for climate dynamics


Inferred greenland temperature

Inferred Greenland temperature


Thermohaline thc record

Thermohaline (THC) record

(57W, 33N), McManus et al.,(Nature, 2004)


Barbados sea level record

Barbados sea-level record


More challenges

More challenges

Champlain Sea was at highest salinity during YD onset (Rodrigues and Vilks, QSR, 1994)

High surface salinity for Gulf of St. Lawrence during YD (de Vernal et al., Nature,1996)

Muddy water sinks (Parsons et al., Sed., 2001)

With sediment loads as low as 1 kg/m^3


Deglacial drainage

Deglacial drainage


Glacial systems model gsm

Glacial Systems Model (GSM)

  • Margin forcing (Dyke, 2003)

  • Large ensemble approach

    • Bayesian calibration of 22 model parameters against a large set of paleo proxies


Drainage topography

Drainage topography

  • Fast down-slope/storage surface drainage solver: dt=100 years

  • Coarse grained topography derived from HYDRO-1K DEM


Drainage ensembles

Drainage ensembles

  • 50 member sub-ensembles

  • Best from Bayesian calibration: 92A, but strandline misfits ->

  • Further hydrological tuning: 11P, 11Y

    • Red River (RR)

    • Wampum (W)

    • Lake Athabasca (A)

    • Great Slave Lake (GS)

    • Great Bear Lake (GB)


Deglacial eustatic sea level chronology

Deglacial eustatic sea-level chronology


Gulf of mexico discharge

Gulf of Mexico discharge

  • 0.2 dSv present-day flow

  • Largest pulse during mwp1-a inferred from observations


Gulf of mexico discharge comparison

Gulf of Mexico discharge comparison


Mwp1 a drainage map

mwp1-a drainage map

  • Mississippi drainage

  • NW Arctic drainage

  • Labrador Sea drainage

  • Gulf of St. Lawrence drainage

  • Hudson River drainage

  • Pacific drainage

  • -14.6 kyr Mississippi discharge: 0.34 dSv

  • -14.4 kyr Mississippi : 1.7 dSv


Hudson river discharge

Hudson River discharge


Gulf of st lawrence discharge

Gulf of St. Lawrence discharge


Gulf of st lawrence sensitivity

Gulf of St. Lawrence sensitivity


Nw arctic discharge

NW arctic discharge


Arctic discharge sensitivity

Arctic discharge sensitivity


Arctic discharge

Arctic discharge


Yd onset drainage basins

YD onset drainage basins

  • Mississippi drainage

  • NW Arctic drainage

  • Labrador Sea drainage

  • Gulf of St. Lawrence drainage

  • Hudson River drainage

  • Pacific drainage


Nw routing for lake agassiz

NW routing for Lake Agassiz


Nw routing for lake agassiz sensitivity

NW routing for Lake Agassiz sensitivity


Lake agassiz choke point elevations

Lake Agassiz choke point elevations


Where does the meltwater go

Where does the meltwater go?

  • Bauch et al (QSR, 2001): evidence of a low salinity event at or before YD onset in western Fram Strait


Climate and meltwater phasing

Climate and meltwater phasing


Summary

Summary

Largest (1.7 to 2.3 dSv over 100 years) discharge into the NW Arctic Basin during YD onset

Most of NW discharge is due to the reduction of the Keewatin ice dome: thus independent of Lake Agassiz routing uncertainties

Trigger for YD?

Ensemble NA contributions to mwp-1a range from 7.2 to 11.4 m eustatic

Large (1.5-2 dSv over 100 years) meltwater pulses into both the Gulf of Mexico and Eastern seaboard

GSM + calibration = data and physics integration


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