MODELING LAURENTIAN GREAT LAKE LEVELS OVER THE LAST SEVERAL HUNDRED YEARS USING NORTH PACIFIC TREE RINGS

Parker Calkin's research involved investigations of climate change along the Gulf of Alaska and reconstructing past levels of the Great Lakes. Here we link the two regions using temperature-sensitive ring-width series from the Gulf of Alaska that are strongly and negatively correlated with monthly lake levels in the Erie, Ontario, Huron and Michigan basins. The linkages between the two datasets reflects the Pacific North American teleconnection pattern.

A well-verified dendroclimatic model based on tree ring chronologies from the Gulf of Alaska explains 51% of the variance in annual Lake Erie levels. The reconstruction extends back 265 years and shows that annual lake levels were high during the mid 1700s, the mid to late 1800s and the late 1900s. Relative low stands occurred during the late 1700s and early 1900s. The highest lake levels in the reconstruction are over the past few decades, as seen in the observed record. In addition to the Lake Erie reconstruction, similar successful modeling of Lakes Michigan – Huron and Ontario is underway. These tree-ring based models explain over 30% of the lake level variance and extend back into the early 17th century. Multidecadal to century-scale lake fluctuations that are recognized in sediment records through much of the Holocene from Lake Michigan are detected in the lake reconstructions suggesting similar controls on lake levels over the last several hundred years.