Ryan asks how a 10-year-old kid could have crossed this fast moving river, Nancy responds that thirty years of global warming means the river would have been frozen over back then. Based that the temperature must be 50°F or higher, due to no visible condensation of their breathe, the temperature would have to be at least 40° colder than it is right now, and global warming does not account for that much of a difference. Even in the dead of winter in Ellsworth, ME, the proximity to the coast and typical winter temperatures would have prevented a fast moving river from freezing over enough to support the weight of a person.
Actually, the river shown is not very deep, and could have been easily waded, so global warming would have nothing to do with crossing the river.