It is an expected aberration caused by CO^2 intoxication of the local atmosphere. The lake froze, because the warming planet sucked all the heat out of the water, by warming the water enough that all the CO^2 phizzed out of it, like a warm soda, taking the heat with it and transferring it to the atmosphere.
Hot planet causes iced over lake.
If you have any more questions about this, I’ll be glad to answer them; you can contact me via the nice nurses on the third floor of Belleview, who are taking care of me until I can regain my imperial throne in France.