Mark,

I offer this data because, at least after the mid 80's, these are direct observations by me. The observations from the 70's was by a previous resident and apparently nobody was writing anything down for a couple of years.

Riley Lake is located about 15 miles SW of Minneapolis. In recent years there has been some significant increase in residential development out here, but for most of that data set I could look out my window (at least in the winter when I could see through my maples!) and see farmland. Weather is in general from the West here. It is possible the city is affecting our temperature here some, but I would have a hard time blaming everything on that.

I'll also grant that this is a small sample. That is a good point, but this is all I have. Much larger durations are recorded for lakes in MN and many other northern many states, but that data is held by government agencies and therefore may be dismissed by those that are suspicious of manipulations. You can be suspicious of me as well, but I can only assure you that this is raw and unadulterated data and it shows a relatively long term trend. In fact, most ice cover data I have seen shows a slower trend than I show here, perhaps because of a longer observation period, or more distance from urban heat islands. But every set of data I have seen show later freezes and earlier thaws. I have seen nothing trending the other way. This isn't fake data, it's direct observations, and in my case, personal observations. I sail iceboats in the winter all over the midwest and pay close attention to when the ice is safe on both ends of the season.

So interpret this however you want. I just thought I'd share with you folks.