A subtropical fate awaited freshwater discharged from glacial Lake Agassiz
Article first published online: 10 FEB 2011
Copyright 2011 by the American Geophysical Union.
Geophysical Research Letters
Volume 38, Issue 3, February 2011
How to Cite
2011), A subtropical fate awaited freshwater discharged from glacial Lake Agassiz, Geophys. Res. Lett., 38, L03705, doi:10.1029/2010GL046011., and (
- Issue published online: 10 FEB 2011
- Article first published online: 10 FEB 2011
- Manuscript Accepted: 28 DEC 2010
- Manuscript Revised: 15 DEC 2010
- Manuscript Received: 1 NOV 2010
- abrupt climate change;
- buoyant flow
 The 8.2 kyr event is the largest abrupt climatic change recorded in the last 10,000 years, and is widely hypothesized to have been triggered by the release of thousands of kilometers cubed of freshwater into the North Atlantic Ocean. Using a high-resolution (1/6°) global, ocean-ice circulation model we present an alternative view that freshwater discharged from glacial Lake Agassiz would have remained on the continental shelf as a narrow, buoyant, coastal current, and would have been transported south into the subtropical North Atlantic. The pathway we describe is in contrast to the conceptual idea that freshwater from this lake outburst spread over most of the sub-polar North Atlantic, and covered the deep, open-ocean, convection regions. This coastally confined freshwater pathway is consistent with the present-day routing of freshwater from Hudson Bay, as well as paleoceanographic evidence of this event. Using a coarse-resolution (2.6°) version of the same model, we demonstrate that the previously reported spreading of freshwater across the sub-polar North Atlantic results from the inability of numerical models of this resolution to accurately resolve narrow coastal flows, producing instead a diffuse circulation that advects freshwater away from the boundaries. To understand the climatic impact of freshwater released in the past or future (e.g. Greenland and Antarctica), the ocean needs to be modeled at a resolution sufficient to resolve the dynamics of narrow, coastal buoyant flows.