What were The Water Wars (24-25) and The Melt (25)? in "Story: Part One"

The Water Wars raged for ten years. Humans polluted the Great Lakes until they were poison, and they sold rivers to the highest bidder, diverting bodies of water to the south and the east. At the same time, earthquakes and hurricanes led the ocean to swallow up coastal lands like California. The North melted and was flooded. The world entered a darker era, as half of the population died and most people stopped reproducing and dreaming. Miig explains that they are heading north because according to the tales the tough northern people are doing okay.