Good day brother :)

To answer your question why the earth is at war, let us know who rule this world now..

2 Corinthians 4:4
Satan, who is the god of this world, has blinded the minds of those who don’t believe. They are unable to see the glorious light of the Good News. They don’t understand this message about the glory of Christ, who is the exact likeness of God.

we all know that satan is the father of lies and his main goal is to corrupt humanity and that the reason why earth is always in chaos. But his reign will not last forever.

Revelation 12:9
The great dragon was hurled down—that ancient serpent called the devil, or Satan, who leads the whole world astray. He was hurled to the earth, and his angels with him.

Then to answer your second question, why are we experiencing such tragedies caused by nature which is controlled by God.

Jame 1:2-4
Consider it pure joy, my brothers and sisters, whenever you face trials of many kinds, because you know that the testing of your faith produces perseverance. Let perseverance finish its work so that you may be mature and complete, not lacking anything.

Keep on believing my friend and don't be deceive in this world. ☺