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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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 America and

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

Model and data

Drainage results

Implications for climate dynamics



Thermohaline thc record
Thermohaline (THC) record America and

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



More challenges
More challenges America and

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 America and


Glacial systems model gsm
Glacial Systems Model (GSM) America and

  • Margin forcing (Dyke, 2003)

  • Large ensemble approach

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


Drainage topography
Drainage topography America and

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

  • Coarse grained topography derived from HYDRO-1K DEM


Drainage ensembles
Drainage ensembles America and

  • 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)



Gulf of mexico discharge
Gulf of Mexico discharge America and

  • 0.2 dSv present-day flow

  • Largest pulse during mwp1-a inferred from observations



Mwp1 a drainage map
mwp1-a drainage map America and

  • 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





Nw arctic discharge
NW arctic discharge America and



Arctic discharge
Arctic discharge America and


Yd onset drainage basins
YD onset drainage basins America and

  • Mississippi drainage

  • NW Arctic drainage

  • Labrador Sea drainage

  • Gulf of St. Lawrence drainage

  • Hudson River drainage

  • Pacific drainage





Where does the meltwater go
Where does the meltwater go? America and

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



Summary
Summary America and

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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