Not shown is the method of cutting or melting the ice. Melting could cause a temporary warming of the water.
Most people cut ice with a chain saw. No warming from that.
Jonna is cute and ridiculously young but kind of cool.
Of course, jumping into ice water is a fairly normal Nordic thing. When I was in Greenland, the Danes used to sweat in the sauna and then run out and jump in through a hole in the ice. And then come back and do it all over again. In the nude. But they were also young.