I am from Michigan and this is such BS. The Dunes have been moving for ever (erosion). It actually has been cooler here in the past few years.
I was in that area during the Summer of ‘88. The temperature was up around 100 every day for two months. That was in the 20th. century last time I checked. It has not been as hot there any time since.
I am from the other side of Lake Michigan and can say that the level of the lake is coming up, but still lower than average for the last 30 years. The beaches are extending farther out into the lake than 20 years ago so erosion is not an issue.
If the Lake levels rise, then erosion of bluffs will be a problem, but that is not due to climate change, just higher water levels.
As an aside, I was born in Michigan and loved going to Traverse City area and sleeping bear dunes as a kid.
This summer has been especially cooler than usual.