What is the ruling on the statement of geologists: that trees cause an abundance of rain to fall—by the power of Allah—and that removing them can lead to landslides?

Speech based on theories and experiments is not akin to "casting stones at the unseen" (guessing about the future), but rather an engagement with cosmic causes. The science of the stars is divided into two parts: a computational one, which is permissible and mentioned in the Quran, and an inferential one, where causes are used to deduce events, which is permissible, just as a doctor infers from a pulse.