I feel like all these texts explore the impact of climate on human society. Ibn Khaldun speaks of areas located around the world where it's just uninhabitable because of the geographical location of the sun, where it's either there too much or not enough. Because of this there is a finite amount of space on this Earth that can be lived in, with some areas being more favorable than others. Montesquieu talks about how the climate of different places affects the society’s culture and laws. One example I liked was how he mentioned that hotter climates would favor water based laws, and colder climates would like alcohol based laws. These changes and viewpoints of these two substances differ between climates. Buffon talks about how if humans don’t like the climate or environment of an area they can change it, by the way of farming for food that wasn’t there, clearing forests. This is fine because we were originally servants of nature, and have ways to coexist with it. But as time passes these previous ways of coexistence fade away into barbarism and we become destructive. Finally Humboldt speaks about how humans affecting the climate of today will affect future generations and change human society. Because of this ever changing climate that we place upon ourselves, we have to continue to learn more about the prevention or consequences of certain actions that affect our climate.
Great observations about these differences, many of which I hadn't thought of. You're getting at something very important in the point about the sun. In some ways, the whole arc of climate theory is a modification of the solar hypothesis. And maybe one thing that Montesquieu introduces is the role of cultural action in the generation of hot and warm influences.