The thing that most struck me about these four pieces is how deeply each author was impacted by where they were from. Each author orients the global climate around their respective home which speaks often to roots of colonial/imperial ideology but also to the unique and important relationships we all have with the environment. Ibn Khaldun's piece, The Muquaddimah, shows an amazingly accurate understanding of climate for the medieval period, especially in regards to how climate affects skin color. He notably places his home as the "best" climate which produces the most temperate people. Similarly in Montesquieu's The Spirit of Laws he argues that cold makes people bolder, stronger, and in all ways better and warmth makes them meeker, and notably worse in battle. When moving into Buffon's work there is a shift in attitude towards the environment over the 18th century. Instead of arguing for the superiority of a northern climate Buffon describes the importance of cultivation of and extraction from the land. There is a shift from the impact of land on people to the impact of people on land. Finally Humboldt views nature as something that must be understood and with a kind of awe and appreciation not seen in the other authors. Humboldt is operating within the new empirical bounds of science and feels emboldened in his ability to achieve true understanding of the natural world and a subsequent dominion over it. I don't know whether we will ever truly confidently understand how every element of the world we live in works but from a historical perspective I am suspicious of any intellectual movement that discounts all the conclusions of its forbearers.
Great point about the shift from the impact of land on people to the impact of people on land. And I totally agree about the last points.