According to the Catholic Church, if God is just and loving why is Nature so needlessly brutal and cruel sometimes?

Romans 8:20-23 speaks to this issue. God has subjected the creation to futility that we might not set our hearts on this world but prefer the next.

From the Homilies of St. John Chrysostom (see Homilies of Chrysostom on Romans 8):

Romans 8:20 For the creature was made subject to vanity, not willingly, but by reason of him who hath subjected the same in hope,

Romans 8:21 Because the creature itself also shall be delivered from the bondage of corruption into the glorious liberty of the children of God.

Romans 8:22 For we know that the whole creation groaneth and travaileth in pain together until now.

Ver. 22. "For we know that the whole creation groaneth and travaileth in pain together until now." Observe, how he shames the hearer, saying almost, Be not thou worse than the creation, neither find a pleasure in resting in things present. Not only ought we not to cling to them, but even to groan over the delay of our departure hence. For if the creation doth this, much more oughtest thou to do so, honored with reason as thou art. But as this was not yet enough to force their attention, he proceeds.

Ver. 23. "And not only they, but ourselves also, which have the first-fruits of the Spirit, even we ourselves groan within ourselves."

That is, having had a taste of the things to come. For even if any should be quite stone hard, he means what has been given already is enough to raise him up, and draw him off from things present, and to wing him after things to come in two ways, both by the greatness of the things that are given, and by the fact that, great and numerous as they are, they are but first-fruits. For if the first-fruits be so great that we are thereby freed even from our sins, and attain to righteousness and sanctification, and that those of that time both drave out devils, and raised the dead by their shadow (Acts 5:15), or garments (ib. xix. 12), consider how great the whole must be. And if the creation, devoid as it is of mind and reason, and though in ignorance of these things, yet groaneth, much more should we. Next, that he may give the heretics no handle, or seem to be disparaging our present world, we groan, he says, not as finding fault with the present system, but through a desire of those greater things. And this he shows in the words, "Waiting for the adoption." What dost thou say, let me hear? Thou didst insist on it at every turn, and didst cry aloud, that we were already made sons, and now dost thou place this good thing among hopes, writing that we must needs wait for it? Now it is to set this right by the sequel that he says, "to wit, the redemption [1428] of our body." That is, the perfect glory. Our lot indeed is at present uncertainty to our last breath, since many of us that were sons have become dogs and prisoners. But if we decease with a good hope, then is the gift unmovable, and clearer, and greater, having no longer any change to fear from death and sin. Then therefore will the grace be secure, when our body shall be freed from death and its countless ailments (or passions). For this is full redemption (apolutrosis), not a redemption [1429] only, but such, that we shall never again return to our former captivity. For that thou mayest not be perplexed at hearing so much of glory without getting any distinct knowledge of it, he partially exposes to thy view the things to come, setting before thee the change of thy body (Gr. changing thy body), and along with it the change of the whole creation. And this he has put in a clearer light in another passage, where he says, "Who shall change our vile body, that it may be fashioned like unto His glorious Body." (Philippians 3:21.) And in another place again he writes and says, "But when this mortal shall have put on immortality, then shall be brought to pass the saying that is written, Death is swallowed up in victory." (1 Corinthians 15:54.) But to show, that with the corruption of the body the constitution of the things of this life will also come to an end, he wrote again elsewhere, "For the fashion of this world passeth away." (1 Corinthians 7:31.)

Ver. 24. "For we are saved by hope," he says.

Now since he had dwelt upon the promise of the things to come, and this seemed to pain the weaker hearer, if the blessings are all matter of hope; after proving before that they are surer than things present and visible, and discoursing at large on the gifts already given, and showing that we have received the first fruits of those good things, lest we should seek our all in this world, and be traitors to the nobility that faith gives us, he says, "For we are (Gr. were) saved by hope." And this is about what he means. We are not to seek our all in this life, but to have hope also. For this is the only gift that we brought in to God, believing Him in what He promised shall come, and it was by this way alone we were saved. If then we lose this hope, we have lost all that was of our own contributing. For I put you this question, he would say, Wert thou not liable for countless sins? wert thou not in despair? wert thou not under sentence? were not all out of heart about thy salvation? What then saved thee? It was thy hoping [1430] in God alone, and trusting to Him about His promises and gifts, and nothing besides hadst thou to bring in. If it was this then that saved thee, hold it fast now also. For that which afforded thee so great blessings, to a certainty will not deceive thee in regard to things to come. For in that it found thee dead, and ruined, and a prisoner, and an enemy, and yet made thee a friend, and a son, and a freeman, and righteous, and a joint-heir, and yielded such great things as no one ever expected even, how, after such munificence and attachment, will it betray [1431] thee in what is to follow? Say not to me, hopes again! expectations again! faith again! For it is in this way thou wert saved from the beginning, and this dowry was the only one that thou didst bring in to the Bridegroom. Hold it then fast and keep it: for if thou demandest to have everything in this world, thou hast lost that well-doing of thine, through which thou didst become bright, and this is why he proceeds to say, "But hope that is seen is not hope; for what a man seeth, why doth he yet hope for?"

One may also appeal to the creation account in Genesis. When man fell in Genesis 3, as the head of this world, all his dominion fell with him, which included the animals and the very ground, which was cursed. Genesis 9:2 also indicates a change in nature:

The fear and dread of you will fall on all the beasts of the earth, and on all the birds in the sky, on every creature that moves along the ground, and on all the fish in the sea; they are given into your hands.

It was at this point, following Noah's flood, that man was given permission to eat animals.

3 Everything that lives and moves about will be food for you. Just as I gave you the green plants, I now give you everything.

Carnivorous behavior prior to the flood may have been a gradually increasing reality, but in a world recently ravaged by a flood, it exploded. A change in the order of creation may at that time have been accompanied by a miraculous change in the makeup of creatures, changing their appetites and even biology.

I believe there are two separate issues here. First is the propensity in nature for brutality. Second is the correlation between suffering and evil. Specifically, is suffering a function of evil?

The Catechism of the Catholic Church addresses both issues. The first passage I'll present is CCC 385

385 God is infinitely good and all his works are good. Yet no one can escape the experience of suffering or the evils in nature which seem to be linked to the limitations proper to creatures: and above all to the question of moral evil. Where does evil come from? "I sought whence evil comes and there was no solution", said St. Augustine, and his own painful quest would only be resolved by his conversion to the living God. For "the mystery of lawlessness" is clarified only in the light of the "mystery of our religion". The revelation of divine love in Christ manifested at the same time the extent of evil and the superabundance of grace.We must therefore approach the question of the origin of evil by fixing the eyes of our faith on him who alone is its conqueror.

All of God's works are good. The lion is not cruel in hunting for food. It does not maim for sport. It's acts of brutality are not associated with evil. Indeed, it is man who brings evil into the world with original sin.

Of the animals being eaten? Removing old, weak, sick animals from the ecosystem makes the ecosystem stronger. There is no evidence I know of that insects feel pain. What looks brutal to you or me may in fact cause no suffering at all.

But of course there is suffering in the world - lots of suffering. CCC 272 states

272 Faith in God the Father Almighty can be put to the test by the experience of evil and suffering. God can sometimes seem to be absent and incapable of stopping evil. But in the most mysterious way God the Father has revealed his almighty power in the voluntary humiliation and Resurrection of his Son, by which he conquered evil. Christ crucified is thus "the power of God and the wisdom of God. For the foolishness of God is wiser than men, and the weakness of God is stronger than men." It is in Christ's Resurrection and exaltation that the Father has shown forth "the immeasurable greatness of his power in us who believe".

God is wiser than man. At worst, it's not for us to understand why suffering occurs. At best, it's a way for us to strengthen our faiths.

1500 Illness and suffering have always been among the gravest problems confronted in human life. In illness, man experiences his powerlessness, his limitations, and his finitude. Every illness can make us glimpse death. 1501 Illness can lead to anguish, self-absorption, sometimes even despair and revolt against God. It can also make a person more mature, helping him discern in his life what is not essential so that he can turn toward that which is. Very often illness provokes a search for God and a return to him.

Even in our worst struggles, suffering can lead to a personal enlightenment, encouraging a deeper understanding of the divine.

In conclusion, suffering is a necessary part of the human condition. Suffering in the animal kingdom is harder to draw any conclusions from, but in most cases is likely anthropomorphic. Evil is not necessary for suffering to occur, and suffering is not necessary for evil to occur.

The best possible answer to this, in my opinion, is none but the one given in the Catechism of the Catholic Church, under the heading "Providence and the scandal of Evil". I quote in extenso:

309 If God the Father almighty, the Creator of the ordered and good world, cares for all his creatures, why does evil exist? To this question, as pressing as it is unavoidable and as painful as it is mysterious, no quick answer will suffice. Only Christian faith as a whole constitutes the answer to this question: the goodness of creation, the drama of sin and the patient love of God who comes to meet man by his covenants, the redemptive Incarnation of his Son, his gift of the Spirit, his gathering of the Church, the power of the sacraments and his call to a blessed life to which free creatures are invited to consent in advance, but from which, by a terrible mystery, they can also turn away in advance. There is not a single aspect of the Christian message that is not in part an answer to the question of evil.

310 But why did God not create a world so perfect that no evil could exist in it? With infinite power God could always create something better. But with infinite wisdom and goodness God freely willed to create a world "in a state of journeying" towards its ultimate perfection. In God's plan this process of becoming involves the appearance of certain beings and the disappearance of others, the existence of the more perfect alongside the less perfect, both constructive and destructive forces of nature. With physical good there exists also physical evil as long as creation has not reached perfection.

311 Angels and men, as intelligent and free creatures, have to journey toward their ultimate destinies by their free choice and preferential love. They can therefore go astray. Indeed, they have sinned. Thus has moral evil, incommensurably more harmful than physical evil, entered the world. God is in no way, directly or indirectly, the cause of moral evil. He permits it, however, because he respects the freedom of his creatures and, mysteriously, knows how to derive good from it:

• For almighty God. . ., because he is supremely good, would never allow any evil whatsoever to exist in his works if he were not so all-powerful and good as to cause good to emerge from evil itself.

312 In time we can discover that God in his almighty providence can bring a good from the consequences of an evil, even a moral evil, caused by his creatures: "It was not you", said Joseph to his brothers, "who sent me here, but God. . . You meant evil against me; but God meant it for good, to bring it about that many people should be kept alive." From the greatest moral evil ever committed - the rejection and murder of God's only Son, caused by the sins of all men - God, by his grace that "abounded all the more", brought the greatest of goods: the glorification of Christ and our redemption. But for all that, evil never becomes a good.

313 "We know that in everything God works for good for those who love him." The constant witness of the saints confirms this truth:

• St. Catherine of Siena said to "those who are scandalized and rebel against what happens to them": "Everything comes from love, all is ordained for the salvation of man, God does nothing without this goal in mind."

  • St. Thomas More, shortly before his martyrdom, consoled his daughter: "Nothing can come but that that God wills. And I make me very sure that whatsoever that be, seem it never so bad in sight, it shall indeed be the best."

  • Dame Julian of Norwich: "Here I was taught by the grace of God that I should steadfastly keep me in the faith. . . and that at the same time I should take my stand on and earnestly believe in what our Lord shewed in this time - that 'all manner [of] thing shall be well.'"

314 We firmly believe that God is master of the world and of its history. But the ways of his providence are often unknown to us. Only at the end, when our partial knowledge ceases, when we see God "face to face", will we fully know the ways by which - even through the dramas of evil and sin - God has guided his creation to that definitive sabbath rest for which he created heaven and earth.

(References eliminated. See original text to recover them.)

Thus, focusing particularly on natural disasters, we read that creation has not reached perfection. Naturally, we are part of the creation, and evidently we have not reached perfection yet (hence, as part of our freedom of will, evil exists). Notice that natural disasters could well be due to evil too (e.g. greed leading to global warming). What is important however is that, creation being God's plan, God would not allow evil (or natural disasters, in this case) to exist if good could not come out of it. This is patent in so many dimensions, like solidarity examples arising after a natural disaster. In a sense, like with every other thing which is beyond our control, natural disasters remind us that (i) we are temporarily on Earth, and (ii) we must trust God only. The latter is certainly consistent with the end of the quote above, that ultimately "the ways of his providence are often unknown to us.", and so we must trust in Him.