:check: Global warming is a huge theme in the story because it's the reason why the weather is so bad and the original reason why the whites started fighting with the indians again. The way it happened is described multiple times throughout the story
“THE EARTH WAS broken. Too much taking for too damn long, so she finally broke. But she went out like a wild horse, bucking off as much as she could before lying down. A melting North meant the water levels rose and the weather changed. It changed to violence in some cases, building tsunamis, spinning tornados, crumbling earthquakes, and the shapes of countries were changed forever, whole coasts breaking off like crust''
The author is using real life events and threats to raise awareness on the fate that's reserved for humanity if we continue like this.