Severe Climates Could Close the Great Lakes
Ann Arbor, MI — If severe climates become the norm - that is, notably drier and warmer for many years due to global warming - the Great Lakes are predicted to close (due to reduced or no outflow) in the following order: Erie, Superior, Michigan-Huron, and Ontario.
By using systematic shifts in precipitation, temperature, and humidity relative to the present climate, researchers have identified candidate climates that likely will result in closed or terminal lakes, as also may have happened in the geological past.
Thomas E. Croley II of the Great Lakes Environmental Research Laboratory (GLERL) and C. F. Michael Lewis of Geological Survey of Canada's Bedford Institute of Oceanography applied GLERL's Advanced Hydrologic Prediction System, modified for dynamic lake areas. They explored the deviations from present temperatures and precipitation that would cause the Great Lakes to become terminal (closed) systems as a result of water levels falling below the outlet sills. The researchers modeled our present-day lakes according to their pre-development natural outlet and water flow conditions, and considered the upper and lower Great Lakes separately with no river connection, as occurred during the early Holocene post-glacial times.
A recent empirical model of glacial-isostatic rebound uplift showed that the Lakes Huron- Michigan levels were below the lowest possible outlet about 7,900 14C years ago, at which time the upper Great Lakes were dependent for water supply on precipitation alone, as at present. At that time, the upper Great Lakes appear to have experienced a severe dry climate that may have also influenced the lower Great Lakes. The present study thus indicates that for severe enough climates, the Great Lakes again could become terminal.
Original Publication Information
Results of this study "Warmer and Drier Climates that Make Terminal Great Lakes," are reported by Thomas E. Croley II and C. F. Michael Lewis in the latest issue (Volume 32, No. 4, pp. 852-869) of the Journal of Great Lakes Research, published by the International Association for Great Lakes Research, 2006.
Contacts
For more information about the study, contact Mike Lewis, Graduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882; miklewis@nrcan.gc.ca; (902) 426-7738.
For information about the Journal of Great Lakes Research, contact Marlene Evans, Editor, National Water Research Institute, 11 Innovation Boulevard, Saskatoon, SK, S7N 3H5, Canada; editor@iaglr.org; (608) 692-1076.
Links
Since 1967, IAGLR has served as the focal point for compiling and disseminating multidisciplinary knowledge on North America's Laurentian Great Lakes and other large lakes of the world and their watersheds. In part, IAGLR communicates this knowledge through publication of the Journal of Great Lakes Research, available to members in print and electronic form. A searchable archive of the journal is available online and includes the abstracts of articles from the journal's inception in 1975 through the most recent issue. In addition, complete articles are available to members who have signed up for an electronic subscription.