The is no question that a general environmental warming will have significant impact on the Northwoods, as it will everywhere. This is not the forum to debate our climatic future, nor the extent to which that future is shaped by the actions of humans; rather, it is assumed that we are entering into a period of warming, possibly if not probably a significant one.
Since recreation is key to the Northwoods economy, climate change could have significant economic as well as ecological impact. Warmer winters could easily make the snowmobile season to short to be economically viable, or could eliminate it altogether. Warmer summers might make vacationing in the Northwoods less pleasant, but warming throughout the entire region should leave the Northwoods cooler than most of the United States. And the lakes would remain an incredible asset regardless of warming.
Brian Fagan, in his book The Great Warming using the warm period of approximately 800 to 1300 A.D., generally referred to by climatologists as "the great warming", as a basis for looking at climate impacts on civilizations. His conclusion is that they are often significant. He also points out that for much of the world, the great warming really meant the great drought. While it brought some salutary effects to Europe (think of the period of the construction of the great cathedrals and the emergence from the dark ages), for much of the world the effect of warming was significant drought. Nothing from that period really enlightens the possible effect of warming on the Northwoods.