8.2 kyr: Model + Data -> North American Meltwater Discharge Lev Tarasov and W. R. Peltier University of Toronto

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 Fast down-slope/storage surface drainage solver: dt=100 years Coarse grained topography derived from HYDRO-1K DEM

Deglacial drainage impact on climate?

Deglacial drainage impact on climate?

Deglacial drainage impact on climate?

Pre-collapse sequence

Pre-collapse sequence

Collapse

Summary Atlantic and Arctic discharge “appear to have little impact” during late deglacial stage Does -8.2 kyr event result just from outburst flood or from large sustained discharge over more than 200 years? Especially given “phase delay between outburst flood and inferred climate event”

Agassiz lake volume chronology

Calibration data