Catastrophic Drainage From the Northwestern Outlet of Glacial Lake Agassiz During the Younger Dryas

Catastrophic meltwater drainage from glacial Lake Agassiz has been hypothesized as a trigger for large-scale ocean circulation change initiating the Younger Dryas cold reversal. Here we quantify the flood discharge that formed the northwestern outlet of Lake Agassiz using a one-dimensional step-backwater model and a zero-dimension gradual-incision model. Applying these two independent models, we estimate a peak discharge range of 1.8-2.5 x 10(6) m(3) s(-1) and a flood volume of similar to 21,000 km(3). Such a discharge can only be derived from Lake Agassiz rather than one of the two smaller regional glacial lakes: Churchill or Meadow. When coupled with existing ice margin chronologies, these results demonstrate that the northwestern outlet of Lake Agassiz provides a viable link for catastrophic meltwater to drain to the Arctic Ocean over a 6-9 month period during the Younger Dryas, though it is unclear whether this was near its beginning.

Automated summary

The study quantifies the catastrophic meltwater drainage from glacial Lake Agassiz during the Younger Dryas cold reversal using mathematical models, indicating that the flood discharge could only come from Lake Agassiz and not smaller glacial lakes in the region. This suggests that the northwestern outlet of Lake Agassiz played a key role in draining meltwater to the Arctic Ocean during the Younger Dryas period.