Firstly, the immense influence of humanity on climate and the ecology of a planet and the intertwined nature between social activity and ecology, the motivation for negative impacts on the ecology lying in the exploitation and overuse of the planets resources, and third the disproportionate impact of this on native populations, and the inability of people to understand the consequences of disturbing complex systems. (no surprise given that Herbert was intellectually close to systems thinkers from Santa Fe)
You think Dune does not address climate change because in the story the planet was already deserted? Do you think Animal Farm is a book about pigs?