When Catholics are confronted with suffering in the world, we often say that whatever the source of suffering is, whether direct human agency (war, crime, etc.) or natural phenomena (hurricane, earthquake, disease, etc.) are involved that this is "a result of the fall". This makes a lot of since, since as we learn from the bible, "Therefore, just as through one person sin entered the world, and through sin, death, and thus death came to all, inasmuch as all sinned." (Romans 5:12)
One of the things that strikes me, however, is: If the suffering resulting from an earthquake or a hurricane is somehow the result of the fall, what would things have been like had man not fallen? Would there simply be no earthquakes of hurricanes or disease? And yet (unless you're the most literal of young earth creationists) the Earth and the physical processes that make it work were formed long before the fall. There could be a world without hurricanes and earthquakes, but it would be a world that worked a little differently than our own. So unless you want to posit that the physical nature of the Earth changed with the fall (an idea that I think Aquinas would certainly have rejected, since it is as incompatible with Aristotelian natural philosophy as with modern science) that leaves us to wonder what natural disasters would have been like had man not fallen, and why they would have existed at all.
In the past, I've toyed with questions about how perhaps natural disasters would have occurred, but man's reaction to them would have been radically different, because man would not have had the inherent fear of death and lack of trust in God that fallen man has. (Aquinas also thought that man would still have physically died had there not been a fall, and that 'death' in Romans 5:12 indicates spiritual death rather than physical.)
But here's another thought: To what extent was the nature of the universe changed because of the fall of the angels? I've heard it argued that because angels experience God directly, their choice to accept or reject him must have been simultaneous with their creation -- to the extent that that description means anything for creatures that are outside the physical world and thus either outside of time or operating on a much different experience of time than we are. Also, the angels had clearly fallen before the temptation of Eve, since Satan arrives to cause trouble.
So to what extent might the fall of the angels have affected creation?
Tolkein speculates about this in the Silmarilion, where Melkor and the other fallen angels descend upon the earth and assault creation. And indeed, if Satan was capable of tempting Eve, and thus helping to debase God's greatest creation, who is to say that he was not capable of sowing discord and suffering throughout lower creation. Is the nature that we see "red of tooth and claw" in some sense the result of that first fall that took place in the moment of God's first creation?
This is not to suggest a sort of Manichean dualism. Clearly, creation is God's work and the most Satan could ever do is torture it. We know from revelation and Tradition that God's power is such he can turn evil to good ends. When we sin (and when Lucifer sinned) we do not have the power to overcome God's will, even though we act contrary to his wishes. God holds all the cards and makes the rules of the game as well. When we sin, we nonetheless advance God's will, and indeed provide him with the material to achieve even greater good. ("Oh blessed fault! Oh happy sin of Adam!")
I think one of Tolkein's brilliant insights, and one of the ways in which he is thoroughly un-modern, is that he saw clearly in his theological vision of the world that the fallen nature of man and of creation in general was not just a defect to be lamented, but had been incorporated by God into his plan so that even greater examples of virtue and sacrifice might be achieved.