Modeling North American Freshwater Runoff through the Last Glacial Cycle
Open Access
- 1 November 1999
- journal article
- Published by Cambridge University Press (CUP) in Quaternary Research
- Vol. 52 (3), 300-315
- https://doi.org/10.1006/qres.1999.2079
Abstract
The Northern Hemisphere ice sheets decayed rapidly during deglacial phases of the ice-age cycle, producing meltwater fluxes that may have been of sufficient magnitude to perturb oceanic circulation. The continental record of ice-sheet history is more obscured during the growth and advance of the last great ice sheets, ca. 120,000–20,000 yr B.P., but ice cores tell of high-amplitude, millennial-scale climate fluctuations that prevailed throughout this period. These climatic excursions would have provoked significant fluctuation of ice-sheet margins and runoff variability whenever ice sheets extended to mid-latitudes, giving a complex pattern of freshwater delivery to the oceans. A model of continental surface hydrology is coupled with an ice-dynamics model simulating the last glacial cycle in North America. Meltwater discharged from ice sheets is either channeled down continental drainage pathways or stored temporarily in large systems of proglacial lakes that border the retreating ice-sheet margin. The coupled treatment provides quantitative estimates of the spatial and temporal patterns of freshwater flux to the continental margins. Results imply an intensified surface hydrological environment when ice sheets are present, despite a net decrease in precipitation during glacial periods. Diminished continental evaporation and high levels of meltwater production combine to give mid-latitude runoff values that are highly variable through the glacial cycle, but are two to three times in excess of modern river fluxes; drainage to the North Atlantic via the St. Lawrence, Hudson, and Mississippi River catchments averages 0.356 Sv for the period 60,000–10,000 yr B.P., compared to 0.122 Sv for the past 10,000 yr. High-amplitude meltwater pulses to the Gulf of Mexico, North Atlantic, and North Pacific occur throughout the glacial period, with ice-sheet geometry controlling intricate patterns of freshwater routing variability. Runoff from North America is staged in the final deglaciation, with a stepped sequence of pulses through the Mississippi, St. Lawrence, Arctic, and Hudson Strait drainages.Keywords
This publication has 56 references indexed in Scilit:
- Proglacial lakes and the southern margin of the Laurentide Ice SheetPublished by Geological Society of America ,2015
- Millennial timescale variability in ocean/climate modelsPublished by Wiley ,1999
- The Seesaw EffectScience, 1998
- INTCAL98 Radiocarbon Age Calibration, 24,000–0 cal BPRadiocarbon, 1998
- Coupled ocean‐atmosphere model response to freshwater input: Comparison to Younger Dryas EventPaleoceanography and Paleoclimatology, 1997
- A high-resolution model of the 100 ka ice-age cycleAnnals of Glaciology, 1997
- History and drainage of large ice-dammed lakes along the Laurentide Ice SheetQuaternary International, 1995
- Rapid transitions of the ocean's deep circulation induced by changes in surface water fluxesNature, 1991
- A 3-D model for the Antarctic ice sheet: a sensitivity study on the glacial-interglacial contrastClimate Dynamics, 1990
- Volume and Routing of Late-Glacial Runoff from the Southern Laurentide Ice SheetQuaternary Research, 1990