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New study predicts more moderate effects of climate change on Great Lakes water levels

A new study led by Dr. Brent Lofgren of the National Oceanic and Atmospheric Administration’s Great Lakes Environmental Research Laboratory offers a more moderate prediction of the effects of climate change on Great Lakes water levels. Previous studies indicated that climate change would result in significantly lower water levels in the Great Lakes due to increased air temperatures and higher rates of evapotranspiration. Most notably, a 2002 study (also led by Dr. Lofgren) reported that water levels in Lake Michigan and Lake Huron could drop by as much as 4.5 feet (1.38 meters). See Brent M. Lofgren et al., Evaluation of potential impacts on Great Lakes water resources based on climate scenarios of two GCMs, 28 J. Great Lakes Res. 537 (2002). The 2002 study was widely cited in legal scholarship and policy reports as an example of the potential impacts of climate change on Great Lakes water resources.

*Full disclosure - I referenced the 2002 study in: Interstate Water Compacts and Climate Change Adaptation, 5 Environmental & Energy Law & Policy Journal 237 (2010); Climate Change and Great Lakes Waters Resources: Avoiding Future Conflicts with Conservation, 31 Hamline Law Review 641 (2008); and Climate Change and Freshwater Resources, 22 Natural Resources & Environment 30 (Winter 2008).

Climate and hydrology modeling is constantly improving, and improved methodology has produced some welcomed good news for the Great Lakes. The new study predicts either a smaller drop or an actual rise in Great Lakes water levels under varying climate change scenarios. The new study finds fault with the previous methodology, specifically a severe gap in surface energy budget closure resulting from problems with the assumption that air temperature is a valid proxy for potential evapotranspiration across all time scales and climate regimes. The results of the new study are published in the Journal of Great Lakes Research as Effects of using air temperature as a proxy for potential evapotranspiration in climate change scenarios of Great Lakes basin hydrology

Keep in mind that these studies are simply modeled predictions, and climate and hydrology modeling is exceptionally complex and subject to many related variables. We don’t know with certainty what a changed climate will mean for the Great Lakes and the region. As I’ve advocated before, the most reasonable course of action is to implement common sense no-regrets policies for energy and water conservation, while preparing our energy and water infrastructure to adapt to changing climate conditions.