C.F.M. Lewis et al. - Past Changes in the Great Lakes of North America

The Great Lakes are of paramount importance for the economy, and communities of Ontario. Many rely on the lakes for drinking water, recreation, production of hydro-electric power, transport and port facilities. Major variances in the water levels in the lakes could have seriously damaging results. The geologic history of the Great Lakes provides a possible window on how climate change and other controls once affected the hydrology of the area. C.F.M. Lewis and colleagues have recently completed studies on lakebed and beach sediments to relate past climate, hydrology, and limnology. The authors hope that this information will help derive the sensitivity of the lake system to climate change to increase our confidence in modelled projections of future lake conditions. Geological evidence of extremely low lake levels in Lake Huron for example, showed that its water level dropped so much that the lake actually became hydrologically closed around 8790–8990 cal BP when glacial meltwater supply ended, and the climate was drier. Carbon dating and sediment analysis of beach ridges in Lake Michigan has shown that, for millennia, the lake level fluctuated about 0.5 m about every 30 years and up to 1.5 m every 160 years. With the changing climate in Southern Ontario it is not unreasonable to expect lake levels to possibly drop in this century.  Thus accurate estimates of water levels in future climates are important for planning adaptation for transportation, shipping, industry, infrastructure, electric power production, recreation and the local communities that surround the lakes.

For more information contact Mike Lewis or ERCC@nrcan.gc.ca

References
Past changes in the Great Lakes of North America: context for a better understanding of their future; Lewis, C F M; Rea, D K; Hubeny, J B; Thompson, T A; Blasco, S M; King, J W; Reddin, M; Moore, T C, Jr.; in, Proceedings of the International Association of Theoretical and Applied Limnology.(ESS Cont.# 20070274 In Press).

Useful Link
Paleoenvironmental Perspectives on Climate Change