Researchers from Michigan Technological University have warned that the baseline lake level for Lake Superior, Michigan-Huron and Erie are expected to rise between 20-50cm by 2050 because of climate change.
The Great Lakes in the Midwest USA comprise the largest unfrozen freshwater stores on Earth, but the study warns that too much of a good thing can create problems.
Like sea level rise, higher lake levels can increase coastal erosion, change navigation considerations, and increase the risk of coastal flooding. More than 30 million people live along the lakes’ 4,500 miles of coastline in the USA and Canada, including the cities of Chicago, Detroit and Buffalo, New York. Storms and flooding associated with recent record highs have already caused problems in each area.
Presented at the Frontiers in Hydrology meeting on June 23, the study improves upon previous predictions for how water levels in Lakes Superior, Michigan-Huron and Erie will change in the coming decades. Climate modeler Pengfei Xue, of Michigan Technological University, and his team combined a high-resolution regional climate model and a 3D hydrodynamic model, along with hydrologic models, to hone projections for lake-level rise.
The study primarily analyzed precipitation over the lakes, evaporation rates, basin runoff, and inter-lake flows to see how lake level would change by 2050, under the highest-emission scenario. The new, advanced modeling system the researchers developed allowed each of those factors to influence each other in a more realistic way than ever before modeled.
“While we know that all these components must be analyzed and projected holistically, the lake-atmosphere interactions were oversimplified in the past,” said Xue. “What we have built is a system that gives a better representation of the complexity of hydrodynamics and lake-atmosphere interaction and contributes to a more advanced modeling framework necessary for improving the Great Lakes’ hydroclimate projections. This is particularly evident through the markedly improved simulation of lake evaporation.”
While there is uncertainty in the precise magnitude of change due to underlying uncertainty in the climate models, the new modeling system projects the lake levels will increase on average compared to the 2010-2019 period. Based on the average of the models, the water level of Lake Superior is projected to rise 19cm, Lake Erie by 28cm, and the Lake Michigan-Huron system by 44cm on average. But at the high end of the possible range, Lake Erie could see 54cm of rise and Lake Michigan-Huron could see 80cm of rise.
Higher lake levels mean that storms, flooding events and natural variability will have more extreme impacts on the lake shores, and coastal decision makers will have to adapt to higher lake levels in the coming years.
“Looking at the coastal hazards, their probability is going to increase and they will be more severe,” added Xue.